To Identify the Main Challenges Facing Human Resources Managers in Research Proposal

To Identify the Main Challenges Facing Human Resources Managers in Non-Profit Organizations - Research Proposal Example The exploration targets recognizing the significant difficulties the human asset administrators face in managing their workers. A portion of the particular destinations are; to discover the quantity of laborers in every association, their compensation and the quantity of staff in human asset offices, to discover the scholarly capabilities of the laborers and to build up the sort of the board apparatus utilized in the association. An example size of 150 representatives will be utilized which get from fifteen associations. Irregular testing technique is utilized to get the example size that is liberated from biasness. An online poll will be utilized which will be facilitated on www.qualtrics.com and www.surveymonkey.com just as send to the members as email connections. The outcomes will be broke down utilizing Statistical Package for Social Scientists (SPSS). Presentation Foundation data HR comprise of people in an association whose command centers around employees’ exercises and their government assistance. The law necessitates that all associations whether administrative or non-legislative must have a HR division to deal with the requirements of the representatives who are the workforce of the association. Ill-advised treatment of workers results to lackluster showing of the association particularly if the association or organization is after benefit expansion as exploration demonstrates that the around 80 percent of the hierarchical capacities are contributed by the human component of asset. A HR office comprises experts and specialists in the field of human asset. It is the fundamental job of the human asset division to enlist and deal with the workers. It is fundamental that the group directs a legitimate assessment of the capacities and capabilities of the candidates to the positions promoted as this incredibly impacts the activities of the association. The group is entrusted to apply a few estimations with the goal that they can choose the best competitors. Psychometric evaluation causes an enrolling group to pick candidates with the necessary disposition to fit in with the organization’s qualities and standards. Meetings are important which composed tests, telephone meetings or one-on-one meetings planned for assessing the capacity of the possibility to settle on educated choices whenever gave such circumstances while they embrace their obligations. Kiessling and Harvey (2005, p.28) clarify that the human asset group has a task to carry out in auditing worker repayment bundles which incorporate pay rates, recompenses, grants, rewards, get-aways and advancements. Perceiving crafted by the representatives supports their assurance subsequently expanding their assurance to convey their obligations and duties to their best. Arranging is another job which the human asset office is dependable in. creating authoritative schedule d ays is their work. They build up the key arrangement which directs the association for a given timeframe. Re-appropriating of assets and data, organization and market is additionally the duty of HR. Strategies, rules and guidelines inside the association are created by the human asset division. Non-benefits association, because of its extraordinary method of working, it is confronted with difficulties for instance inability to pick the best contender for a given activity position may affect adversely of the exhibition of the organizati

Aqualisa Quartz: Case Study

1. What is the Quartz offer to handymen? What is Aqualisa Quartz offer to customers? The incentive of Aqualisa Quartz to handymen is that it is anything but difficult to introduce; it is increasingly gainful in light of the fact that they can accomplish more establishments. Since the establishment procedure is less muddled, it sets aside less effort to introduce (just a large portion of a day contrasted with 2 days already). This offers handymen the chance to introduce more units and catch a portion of the verifiable half year sitting tight rundown for plumbing employments. Because of a less intricate establishment process, even students can do establishments, rather than just guaranteed handymen. The Aqualisa Quartz item additionally conveys superb outcomes, which gives the handymen expanded validity with customers for introducing an unrivaled item with less glitches. The offer of Aqualisa Quartz to purchasers is that it had effective and dependable water weight and temperature. It is protected to use for children and old individuals. It has a one touch control with a red light pointer which permitted buyers to know when the water arrives at the ideal temperature. When the temperature is set, shoppers just need to push the one touch control and sit tight for the light. It is a lot simpler to introduce for the DIY segment of customers since it doesn't require exhuming of the divider to arrive at plumbing. The Aqualisa Quartz likewise has astounding structure and style. The control box could now be put in any space near a water source and electrical outlet †even in far out areas. 2. For what reason is the Quartz shower not selling? Deals of the Quartz shower are altogether beneath desires. There are a couple of contributing components. Slow Adoption Processes. Most handymen are careful about new innovation and don't confide in it, particularly considering past electronic control disappointments. What's more, handymen set up a solace level with a specific brand and consider changing to be favored item as a superfluous expense. The vulnerability of its presentation, which may bring about accomplishing fix work, in addition to an opportunity to become familiar with another item, is viewed as an impediment. They appear to cling to the standard, â€Å"If it ain't broke, don't fix it. † Although there has not been a lot of reception with the item, handymen additionally may represent a potential test with the structure of their charge chedule. In the event that a work cost of 40 to 80 pounds for each hour was decreased by 75% as a result of the simplicity of establishment, a handyman may need to plan right around three fold the number of shower employments to make up the potential misfortune in labor income or utilize an opportunity to con vey different administrations. Deals Targeting and Cannibalization. With the business power investing 90% of their energy in existing records, there is insufficient spotlight on exchange shops †which target handymen. It additionally makes the danger of cannibalization of the other product offerings. Normally, new items ought to be acquainted with existing clients to either catch new income or supplant maturing items. Another methodology is to acquaint the items with new clients. For this situation, the item presents direct rivalry and the business group appears to be uncertain of how to continue while adding the Quartz to their common deals process. The arrangement is for organizations to pull together the business group to target new clients or section a bit of the business power to spend significant time in a specific product offering. Item Testing versus Market Research. The innovative work group at Aqualisa appear to work admirably of getting criticism from the clients and to figure out what might make the best client experience. Be that as it may, there doesn't have all the earmarks of being any criticism assembled from its essential client base on what issues they are confronting, how this new item may understand them, and at last how it might profit the handymen. The methodology expect handymen will get on the grounds that it was just a superior shower. Be that as it may, that isn't the present circumstance. 3. Aqualisa went through three years and 5. 8 million building up the Quartz. Was the item worth the venture? Is Quartz a specialty item or a standard item? The Quartz line item merits the time and cash that Aqualisa spent creating it. The organization has had the option to make a creative, get through item in a very experienced industry. Given the present valuing model, Aqualisa can earn back the original investment on its speculation by selling somewhat more than 18,700 units (expecting a 50/50 split between the two models advertised). There were 550,000 force shower class units sold in the United Kingdom in 2000, so selling only less than 20,000 of such a prevalent item should be a reachable objective. The Quartz is a standard item that interests to any individual who can bear the cost of it. While the Quartz may have neglected to post solid starting deals numbers there is plainly an interest in the United Kingdom (and presumably the remainder of Europe) for an item that fixes the entirety of the issues related with the old pipes framework that exists in this piece of the world. When there is solid interest and just a single provider that enough tends to all the buyer needs the main missing fixing is an appropriate advertising effort, which is unmistakably inadequate. On the off chance that Aqualisa can viably pass on the advantages of the Quartz units to the two handymen and shoppers sufficiently there is no explanation Quartz can't fuel Aqualisa’s development for the following quite a long while. 4. Aqualisa presently has three brands: Aqualisa, Gainsborough, and ShowerMax. What is the reason behind this different brand procedure? Does it bode well? The demonstration of dealing with various brands is a dainty tight rope walk that can help raise a brand yet practically simply reduce it. Aqualisa includes perceived particular markets inside the general market of showers. An amazing case of various brands can be drawn from the concise tale toward the start of the paper with the referencing of the Marriott that Mr. Rawlinson was a visitor of. Marriot has a huge number of brands inside their image. Buyers come in any and each structure, from the individuals who look for quality first and have the way to take care of the best to the individuals who take a gander at the sticker price first and bargain on quality and wherever in the middle. Marriott comprises of the Courtyard, The Fairfield Inn, Marriott Resorts, and Residence Inn, just to give some examples. The objective is to seclude the requirements and requests of explicit sorts of shoppers and use each brand to practice and oblige that kind of buyer. They have separated their marking into an engineering characterizing the brands classes as; notable extravagance, extravagance, way of life, signature, present day basics, long visit and goal amusement. Something beyond making these branches they have concentrated on particularly setting up a different personality for each brand while as yet exemplifying the general complete brand’s mission. This is a troublesome shuffling act in various brand the executives, wavering to locate the ideal harmony among partition and unification. The lengthy visit class comprises of those rooms including kitchens, and different luxuries to provide food all the more too long haul visitors for instance. Any market is loaded up with a horde of various purchasers so to sum them up with one brand as a ‘one size fits all’ administration would be silly. Marriott has spent an extraordinary entirety of publicizing and promoting dollars and exertion to look into the market and increase knowledge into the requests of the buyer. This has additionally been cultivated by changing valuing focuses, among different components, so as to separate the objective market into various targets. This permits the brand to all the more likely serve every segment explicit needs more proficiently and successfully. Aqualisa perceives a similar pattern inside the shower advertise. As expressed for the situation study, the United Kingdom’s purchasers will in general fall into three estimating fragments: premium, norm, and worth. Aqualisa has created three brands individually: Aquastyle, Gainsborough, and ShowerMax, to enter these business sectors. In addition to the fact that consumers are worried about value usability, establishment and execution. These different elements mean various sorts of end clients. They comprise of the DIY buyers, handymen, engineers and contractual workers, and the retail shopper. These shifting clients each should be reached through particular methods. Tradeshows are the best spot to arrive at handymen and engineers while choices like tool shops and showrooms are best for DIY and retail shoppers. In a market, for example, the shower showcase in the UK, there should be a few systems and techniques for advertise infiltration. So as to best oblige these various techniques, Aqualisa must modify and tailor fit a product offering intended for each market portion. This model is a quintessential example where different marking is the best choice. Simply making one brand for this situation would without a doubt categorize their activity and pigeonhole them as simply being an item for just a couple of kinds of buyers. A solitary brand would thus alienate the necessities of different sorts of interest inside the market. The sheer truth that there are business and private applications bolster the way that numerous item marks are required. Advancing a general message and perfect for your brands that envelops all product offerings and extensions their disparities is basic; Aqualisa has picked a shrewd procedure in seeking after different brands. 5. What ought to Rawlinson do to create deals energy for the Quartz item? Would it be a good idea for him to change his showcasing procedure to target customers legitimately, focus on the DIY market, or target designers? Would it be advisable for him to bring down the cost of the Quartz? Or on the other hand would it be advisable for him to accomplish something else through and through? In spite of the fact that the Quartz is really notable and creative regarding capacity and plan, numerous buyers and industry experts the same are not completely mindful of its highlights and advantages. Aqualisa ought to focus on a forceful showcasing and promoting effort focused towards

Congratulations, Class of 2023!

Congratulations, Class of 2023! Congratulations to those who have been admitted to the University of Illinois, so far! You have worked hard for this moment and the future is only beginning from here. As you celebrate your achievements, there are still some things you have to consider before you join us on campus this fall. 1. Accept/Decline Many of you have received emails regarding your acceptance to Illinois. But, it doesn’t stop there. If you choose Illinois as your future college (which, I mean, who wouldn’t?), you have to accept this admittance. If you haven’t done it already, take a quick detour and do it right now! 2. Housing You can choose to live in University Housing or Private Certified Housing, depending on availability. You can fill out your contract online and via email you will receive a time stamp, which is when you can choose your residence hall. You can go ahead and find a roommate while you’re at it. Usually students resort to Facebook because it’s an easy interface to work with, but the university provides a survey that students can fill out regarding their habits and likes/dislikes. 3. Summer Registration This is a one-day event where students come to campus to meet with academic advisors and register for their first fall semester of classes. If you live far away, don’t worry, you have the opportunity to register through online appointments! 4. Placement Exams You can take placement exams up to two weeks before summer registration to see which level classes you can sign up for. Don’t stress, it’s not as bad as it sounds! These are some of the next steps you can take to enroll in the best four years of your life! Check out the admissions website for more details on the admitted checklist. Kripa Class of 2020 I'm majoring in Psychology, minoring in Spanish, and pursuing a pre-dental track. It seems like I’m all over the place, but that’s what I like about college! I get to choose to study what I’m interested in, and I’m happy to be doing just that at Illinois.

Parenting Styles and Fences Essay - 669 Words

Celon Blair Professor Brown English 102 April 18, 2012 Parenting Styles and â€Å"Fences† Psychology is the study of the human mind and behavior. In psychology there are for parenting styles. They are Authoritarian, Authoritative, Permissive, and Uninvolved. I believe that the best parenting style is Authoritative. This parenting is more involved. They explain rules and punishment. They are open to conversations and questions. Inâ€Å"Fences† by August Wilson we learn that the type of parenting Troy Maxson exhibited was the Authoritarian style. We also explore the minds and behaviors of Troy and Cory Maxson. Is their relationship a strain on them alone or does it affect everyone around them? How, if at all, is their conflict resolved?†¦show more content†¦In an article â€Å"Knowing Yourself and Your Child by Rosenthal, she states that the parenting style of authoritarian has two main components. The two components are responsiveness, or how much independence you’re willing to grant, and demandingness, how much strict obedience you require. The con flict there is that either way you lose. There has to be a balance of the amount of independence you grant and the amount of obedience you require. The conflict in â€Å"Fences†, was that Troy knew neither. He stopped allowing Cory to play sports, taking away his independence and forcing strict obedience on him. Cory had to get the job Troy wanted him to get, be home when Troy wanted him to be home, and after all the the strict demanding the relationship took a serious turn. An estimated amount of 1.6 million adolescents run away from home each year in the U.S alone.(Adolescence 266) Their parents maybe drug addicts or alcoholics, but most likely they are overbearing, controlling, authoritarian parents. The conflict is normally blamed upon the huge generation gap between parent and adolescent. The adolescent becomes increasingly, and dangerously distant. Research shows, that the minority of adolescents have a 20 percent -25 percent high conflict and majority is moderate or low conflict (Adolescence 263). How many times do you listen to your parent say â€Å"when I was young we weren’t allowed in theShow MoreRelatedWhy I Believe in Attachment Parenting Essays1522 Words   |  7 Pagesintroduction to Attachment Parenting. It covers why I believe it is a valid and important way to parent. It believes that children need to have firm foundation of attachment in order to have proper brain development. I cover why I believe so much in this parenting s tyle. It is a very connected way to raise and respond to children. It covers the elements that make-up this parenting style including: co-sleeping and baby wearing. 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Lux, the main character for the rest of film, has some problems of her own thatRead MoreAnalysis Of Charles Burnett s Film, The Killer Of Sheep, And My Brothers Essay2123 Words   |  9 Pageshe is working on the kitchen and he chases after his older son for picking on his younger son. This type of â€Å"tough love† parenting can also be seen in a flashback scene where Stan’s father scolds him for not fighting other children with his brother. By depicting parents as scolding, and forceful when it comes to some values, Burnett shows a realistic view of what parenting can be like for the impoverished. When men like Stan and Stan’s father are concerned with the necessary, and providing forRead MoreEFFECT OF PEER PRESSURE OF STUDENTS ACADEMIC PERFORMANCE IN SECONDARY SCH OOL5933 Words   |  24 PagesCHAPTER TWO Introduction Peers become an important influence on behavior during adolescence, and peer pressure has been called a hallmark of an adolescent experience. 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Battle of Raymond in the Civil War

Koreatown Free Essays

Koreatown, L. A. Four miles SSW from the iconic Hollywood sign and just about the physical center of the City of Angels is Koreatown. We will write a custom essay sample on Koreatown or any similar topic only for you Order Now Koreatown has the largest South Korean population outside of the country itself. With such a high concentration of these richly cultured peoples came many korean style restaurants and other eateries. Though in recent years Koreatown’s Korean population has declined to about 30% of the total population, it is still considered the prime place to enjoy a good dim sum or kimchi. There is a little more than a thousand Korean owned businesses in K-Town and a very good majority of those are eateries. Being known for its nightlife, most of K-Town’s eateries are bars and norebangs (karaoki rooms). â€Å"A night out in what insiders call K-Town might begin with dinner or warm-up drinks and nibbling at a stylish cafe with giant video screens, then proceed to dancing at an exclusive nightclub or singing at a karaoke †music studio† until dawn† (Navarro). Singing in norebangs is a widely appreciated pass-time in the Korean community and is usually accompanied with alcohol and appetizers. This pass-time is never done alone and it is usually done in large groups for any occasion. The alcohol of choice being makgeolli, a fermented rice wine, is usually associated with the cooking and munching of small strips of sweet and crispy pork belly. Small groups of people can be seen around a table drinking, cooking the snack and conversing. Another widely appreciated restaurant type brought over from the Koreas, is the Korean BBQ. Essentially, it is a cook-it-yourself restaurant; the cooks prepare the dishes to be cooked and then hand them out to the customer to be cooked right at their own grill in the middle of the table. This allows the customer to cook the meat to their desired taste and gives more time to converse. Interestingly, it doesn’t have to be eaten with a utensil; usually there would be a plate of large lettuce leaves. It is very common to tear off a piece of the leaf and cup it in one hand while the other picks up a piece of meat with chopsticks and puts it on the leaf. If there is anything else to put on it, like a slice of mushroom, it is put on top, the leaf is rolled up and popped in the mouth. The most popular food in Korean culture is kimchi. It is made primarily from fermented napa cabbage, spicy red pepper powder, and various other vegetables and spices. In most asian cultures, there are many parts to a meal; kimchi is usually a side-dish. The ingredients are quite cheap and the recipe is easy to follow. In low-income families, kimchi is a larger part of the meal. It is the perfect food for these families because it can easily be made in bulk and it can be kept for up to a month in the refrigerator. Kimchi is a staple of Korean society. Korea brought over a very cultured people that are very family and food involved. Food is a very important part of the Korean culture and community as a whole. Work Cited Navarro, Mireya. â€Å"It’s Koreatown, Jake. † The New York Times. The New York Times, 08 Aug. 2004. Web. 3 Nov. 2012. How to cite Koreatown, Essay examples

Stone Age free essay sample

Three-agesystemIn the 1820’s, in order to address the prehistory of mankind more clearly, it was thought necessary to divide it into time periods, thus a ‘three-age’ system of the (1) Stone Age, (2) Bronze Age and (3) Iron Age was adopted. While this system is still more-or-less in common use today, refinements were inevitable and the Stone Age, so immensely long, was later subdivided into three major periods as follows: Paleolithic (c 2,000,000 – c 10,000 B. C. ) (Old Stone Age) The Paleolithic time period is by far the longest, beginning some (circa) two million years ago to coincide with the first evidence of toolmaking and ending around 10,000 B. C. to coincide with the end of the last ice age (Pleistocene epoch). Later, as notable advancements in stone toolmaking capabilities were recognized and identified pertaining to the Paleolithic, it was also subdivided thusly: †¢ Lower Paleolithic (two million – 100,000 B. C. ) †¢ Middle Paleolithic (100,000 – 30,000 B. C. ) †¢ Upper Paleolithic (30,000 – 10,000 B. C. ) Mesolithic (c 10,000 – c 5,500 B.C. ) (Middle Stone Age) This relatively short Mesolithic time period, sometimes called the Epipaleolithic Era in areas where glaciers did not exist, was set-up to cover the period from the last ice age until the introduction of farming considered to have occurred sometime around 5,500 B. C. However, that particular date just represents widespread farming; it apparently was already taking place a few (or several) thousand years earlier in the Middle East. Farming began at different times between the various cultures but was generally more pronounced between continents. From a broad point-of-view, that is, if uniformly applied worldwide, the Mesolithic could overlap the next one (Neolithic) by a few (or several) thousand years. In other words, in one part of the world it could still be Mesolithic (no farming) yet having already advanced to Neolithic (farming) in another. Because of this, its application became regionalized. Neolithic (c 5,500 – c 2,500 B. C. ) (New Stone Age) This very short Neolithic time period, the last part of the Stone Age, was set-up to cover the period from the onset of farming and ending when metal tools came into widespread use. Again, since ‘widespread’ would be a judgment call as to when the next age (Bronze Age) should begin, it would be a matter of opinion. Metal tools in common use (copper) could have begun as early as 6,000 B. C. within some regions of Europe, Asia and North Africa, effectively eliminating the need to refer to any Neolithic time period at these locations. However, it could apply to less advanced regions like the Americas and the rest of Africa. The Neolithic therefore became regionally applied also.

The Influence of Social Networking Sites free essay sample

It is not surprising that many people are hooked on with these sites since it is free and easily accessible with the use of a computer connected to the internet and even with the use of a mobile phone that enables SNS applications or internet browsing. However, does SNS usage affect interpersonal relationships? Do people rely too much on the fastest way communicating on the internet despite the lack of face-to-face interaction? This research aims to determine the effects of SNS to the interpersonal relationships. It also focuses on analyzing the level of interpersonal relationship after using SNS.The research will then consider how social networking sites impact interpersonal relationship in the real world. This research is based on a survey of ____ purposively a third year and fourth year education student respondents that use social networking sites everyday with the status of their interpersonal relationship with family, friends, teachers and others as they use social networking sites. We will write a custom essay sample on The Influence of Social Networking Sites or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Mary’s College. Examples of social networking sites are Friendster, Facebook, Twitter and Plurk. Social Networking Sites help us to communicate with our friends, classmates, and relatives but they also allow us to communicate with other people who share common interests with us. For instance a person added another person as a friend on Facebook since both of them is addicted on playing Restaurant City. Through these SNS, we develop virtual interpersonal relationships. An interpersonal relationship is a relatively long-term association between two or more people.This association may be based on emotions like love and liking, regular business interactions, or some other type of social commitments. Interpersonal relationships take place in a great variety of contexts, such as family, friends, marriage, acquaintances, and are the basis of social groups and society as a whole . Social networking sites influence the interpersonal relationship of students in many ways. Through social networking sites, users come to meet other people Worldwide. These people can affect the user’s interpersonal relationship with other people close to him/her.This influence can either be good or bad for the user. The researcher chose the topic about the influence of social networking sites to be studied because it is shown evidently that most of the students in St. Mary’s College use Social Networking Sites as part of their activities done in the internet. Many students always log into their account on Facebook, Friendster, etc. as a part of their everyday routine. Could you imagine the number of all the students logging in to these social networking sites, everyday? That would be millions of students logging in social networking sites. Why students are interested on these sites? Social networking sites typically offer many features and those features are positively the reason why many students are interested in checking out these sites. One of the general features of SNS is profiles. A profile contains all the information about the person plus their photos, videos, applications that they use and comments/messages posted by other persons. Well, SNS also offers special features like for example, Facebook has social games like Restaurant City and Pet Society.It is evident that many students greatly rely on these sites in order to interact with their friends and other people whether they know them or not. Being dependent to these sites promotes online friendships which are not good since they might encounter people that are suspicious in behavior. These sites hinder face-to-face friendship but many students reason out that they use SNS in order to communicate conveniently with their faraway friends. What do these SNS possess to make the students keep on using them? Why do students upload photos, videos, post comments/messages on other profiles and play social games?What are the benefits and purpose of doing these activities? Why are social networking sites frequently used by students nowadays? The researcher goal is to address these questions and have an in-depth study with regards to those questions stated above. Students’ usage of social networking sites provides long-lasting insights to identity construction, social behavior and peer-to-peer interaction therefore studies such as this arises that found out the real perspective of students about social life. B. Conceptual Framework In general, online relationships contain much weaker ties than face-to-face relationships (Vitak, 2008).Social networking sites such as Facebook offer users a convenient method for maintaining a large number of weak ties. While maintenance of strong ties typically requires significant commitm ents of time and energy, weak ties maybe managed solely through the connections that link Facebook â€Å"friends. † Facebook allows users to stay up-to-date on their weak ties’ lives simply by viewing the information available in those friends’ profiles and by connecting through actions such as pokes, private messages, wall postings and photo comments. By offering multiple methods of interaction, Facebook saves users significant time, thus enabling them to create and maintain a massive social network, although one predominantly composed of weak connections between users. For example, a recent survey found that the average user had 180 friends on the website, which is far more â€Å"friends† than the average person would say they have in the real world (Golder et al. , 2006). In cases where factors such as distance change a face-to-face relationship into a primarily online relationship, strong ties are maintained and even strengthened further.Social networking sites is a tool for person to keep in touch with his distant friends by following their updates, sending a message or posting comments—users have a quick and easy way to stay connected thus keep the relationship healthy when they are too busy to commit more time to face-to-face interaction (Vitak, 2008). For more vivid picture of the study, Figure 1 served as the research paradigm. Paradigm of the Study Social Networking Sites Figure 1. The influence of social networking sites on the interpersonal relationships of the students.The paradigm above shows the influence of social networking sites to the interpersonal relationship of students. There are two possible types of interpersonal relationship that students tend to develop. These are the following: Stronger interpersonal relationship of students with their friends, teachers, and parents. This happens if a student or a person knows well how to use a social networking site. Students are always updated with the status of their close friends, teachers, or even their parents that are added in their friends list in the social networking sites that they are using.

Downloading German Songs from iTunes

Downloading German Songs from iTunes iTunes auf Deutsch! Downloading German music- legally Would you like to explore the world of modern German music? Would you like to download rock, pop, or rap songs in German? How about watching a German music video online? Well, I just did all that, and boy was it fun! Apple must have been listening to the complaints of U.S. fans of German music, who for a long time could only get a tantalizing look at, and even listen to, songs and albums by German (and Austrian) artists, but could not buy any of it from Apples American iTunes Music Store. This frustration has now lessened for Mac and Windows users, but not entirely. A recent visit to the U.S. iTunes Music Store was a pleasant surprise. I found music and songs in German by many contemporary and traditional bands and artists from Austria, Germany, and German Switzerland. And I could buy what I saw/heard! There were albums and songs by DIE PRINZEN, FALCO, HERBERT GRÃâ€"NEMEYER, the PUHDYS, MÃÅ"NCHNER FREIHEIT, and even HEINO. (Youll also find audiobooks in German, language courses, and German comedy recordings available for download.) I discovered just about every type of music in German- from classical to rap, from Christmas to country-western- ready for listening and purchase. Soon I had downloaded (and paid for) an eclectic mix ranging from Deutschland by DIE PRINZEN to Ring aus Feuer (think Johnny Cash) by the Austrian WOLFGANG AMBROS. As I type these words, my computer is playing music by RAMMSTEIN (Amerika), UDO LINDENBERG (Ich habe noch einen Koffer in Berlin), and the interesting Belgian group SCALA KOLACNY BROTHERS (Schrei nach Liebe)- all downloaded from the American iTunes Music Store. Mac or Windows users can then create CDs with the downloaded German songs or any mix they want. If I had an iPod, I could also transfer these songs to it and listen anywhere I go. A Few More Surprises - Good and BadAlthough residents of Germany and Austria can download iTunes music from just about any German recording artist there is, we U.S. residents have to be content with slimmer pickings. If you want to download songs by Die Fantastischen Vier, Rosenstolz, or Die Ärzte, (Die beste Band der Welt) youll have to be in Germany. You can easily switch to the German iTunes Music Store and listen to songs by those artists, but when you try to download a song or album, U.S. residents get this unwelcome message: Your account is only valid for songs from the U.S. iTunes Store. But at least you can listen to 30-second samples of the German songs. Even for artists in German that are found in the U.S. store, not all of the albums or songs by that artist may be offered. Some albums are partial, with only a few selected songs available from iTunes, but that is also true of the normal American or British recording artists. However, what IS there is a lot better than what was available earlier (pretty much nothing). There is no German Songs menu section in the U.S. iTunes store (there is a German Pop category, but youll need help finding it; see Tips Part 2), so I started with a search by the artists name or a song title. Sometimes I just typed in a common German word (liebe, freiheit) to see what results would pop up. As I explored the German offerings with this method in the U.S. store, I stumbled onto interesting things I may not have found otherwise. Schrei nach Liebe is a good example. Turns out the iTunes version I downloaded is a cover version by a Belgian girls choir of that Ärzte song, and the Germans are raving about how the ladies took a metallic song (they also did Engel by Rammstein) and turned it into something very different but still cool. After downloading Amerika by Rammstein, I discovered that its in the German Top 10 charts (Oct. 2004) and that iTunes has a music video version! (Free and in stunning quality with a high-speed connection!) Tips and TricksIn the next section Ill offer some tips and tricks for finding German songs at the U.S. iTunes Music Store, with screen shots, artists lists, links, and other neat stuff- including music videos in German. Note: iTunes also works great for subscribing and listening to podcasts in German!

Demand Utility Marginality Essay Example | Topics and Well Written Essays - 500 words

Demand Utility Marginality - Essay Example For instance in the beauty franchise, such as in a beauty salon, many customers are extremely loyal once they find a location that they truly enjoy. "No way would I give up my hair stylist. You develop these relationships," says Liza Burnett, a 26-year-old in New York, who spends $150 for a hair cut and scalp treatment every two months. The factors that appear to affect the marginal utility of such luxury goods among those with large net worth are many. One of the most primary would be that obviously only those with the monetary resources available would be able to afford an item with such a high price. Another factor, which relevantly ties into the first, is that the salesperson of an item such as this would want to have excellent marketing skills as well as proper customer service skills, in order to sell as best as they possibly can. Although there is a significantly higher number of people in the world today with a bank account full enough to easily purchase items with such a high cost as compared to even fifty years ago, it still takes a good customer service representative to sell efficiently. The marginal utility of a Rolls Royce Silver Cloud to me is the fact that it is "considered to be the most aesthetically pleasing vehicle ever to be produced by the vehicle manufacturer." ("Wikipedia",

The Use of Forecasting Term Paper Example | Topics and Well Written Essays - 500 words

The Use of Forecasting - Term Paper Example There are a number of options that can be used to respond to this situation. Since it is clear the organization will overspend when buying the new computers, then actions plans ought to be implemented to cut down on other costs. One of the options that can be used in this situation relates to staff forecasting (Baker and Baker, 2014). The organization can cut down on the number of staff in order to cut down on costs that would otherwise be spent in purchasing the computers. Since planning for the computers is ongoing, them planning should also be going on to cut down on the staff. This option has its own ramifications. Reduced number of staff will definitely elevate stress levels and burn out and this translates to poor services. Poor services means that patients will also be dissatisfied. Dissatisfied patients in many cases will opt to seek care in other facilities hence leading to decreased revenue for the facility. Expense forecasting as cited by the media can be used to identify the availability of resources (Laureate Education Inc, 2012).Identifying available resources within the organization can help spot resource that can be pulled and be used for other purposes. The second option that can be used in this case scenario therefore is to pull resources meant for other purposes within the institution to cover for deficit outlined in the new expense report. This can also have negative effects on the quality of services and patient satisfaction. The pulled funds may have been intended for quality improvement and hence pulling them will mean that they initially intended purpose will not be achieved. The third option would be to push the extra expenses to the next budget such that the department operates on a deficit the coming year. This might also affect the delivery of services due to insufficient funds but the effects can be

Immune Privilege of Tissue Engineered Articular Cartilage

Immune Privilege of Tissue Engineered Articular Cartilage The immune privilege of tissue engineered articular cartilage derived from mouse adult mesenchymal stem cells and the potential of tissue engineered cartilage as a gene delivery method Chapter 1 Stem cell biology 1.1 Categorization of stem cells Stem cells are generally defined as cells possessing the following 3 characteristics: (1) self-renewal, (2) the ability to produce all cell types made in that tissue, and (3) the ability to do so for a significant portion of the life of the host (Alberts et al., 1989; Reya et al., 2001), while progenitor cells are capable only of multi-lineage differentiation without self-renewal (Weissman, 2000). Stem cells can be classified by their ability to differentiate. The most primitive, totipotent stem cells have the ability to divide and produce all the differentiated cells in an organism, including both the embryonic and extraembryonic tissues of an organism. Totipotent stem cells include the fertilized egg and the cells produced by the initial divisions of it. In mammals, these cell divisions result in an implant in the uterus called the blastocyst. The blastocyst contains an outer sphere of trophoblast cells. Trophoblast cells are capable of implanting into the uterus and helping the form of placenta which provides nutrients to the embryo. Within the blastocyst are 10 to 20 pluripotent cells called the inner cell mass. In mammalian uterus, these inner mass cells will participate in the production of all tissues and organs of the developing embryo, then fetus, then born organism. Such pluripotent cells can produce any differentiated cells in the body, but are usually unable to for m the trophoblast cells. The best-known pluripotent stem cell is the embryonic stem (ES) cell, which are obtained from the inner cell mass of the blastocyst and exist for only a brief stage of embryonic development. The last major class of stem cells, multipotent stem cells, gives rise to a limited number of cell types which are responsible for organ growth and renewal such as neural stem cells, skin stem cells and haematopoietic stem cells (HSCs) (Cheshier et al., 2009). 1.2 Selected milestones of stem cell research In 1981, Martin isolated a pluripotent stem cell line from early mouse embryos (Martin, 1981). Wilmut in 1996 first cloned a mammal, a lamb named Dolly by transferring nuclear from the adult mammary gland cell to an enucleated unfertilized egg (Wilmut et al., 1997). In 1998, Thomson obtained the first human embryonic stem cell line from human blastocysts (Thomson et al., 1998). In 2001, President Bush banned scientists from using federal funds to study stem cells from sources other than those that had already been grown because of the ethical concerns. To avoid ethical dispute over the use of human embryonic cells for research purposes, many efforts have been taken on obtaining pluripotent stem cells from differentiated donor cells. In 2006, Yamanaka find a way to obtain pluripotent cells by reprogramming the nucleus of adult mice skin cells (Takahashi and Yamanaka, 2006). Such cells are now known as induced pluripotent stem (iPS) cells. 1.3 A brief introduction of several types of multipotent stem cell The best known multipotent stem cells are haematopoietic stem cells (HSCs), that give rise to all the blood cell types including myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells). HSCs are vital elements in bone-marrow transplantation, which has already been used extensively in therapeutic settings (Reya et al., 2001). In the long-term culture systems, human and rodent Central Neural System (CNS) cells maintain the capacity to produce the three main mature cell classes of the CNS: neurons, astrocytes, and oligodendrocytes, which suggest stem cells and/or progenitors exist and can survive in the culture medium (Weiss et al., 1996; Carpenter et al., 1999). In 2000, Human CNS stem cells (hCNS-SCs) have been successfully isolated by FACs (Uchida et al., 2000). Cancer stem cell hypothesis was proposed by Reya 2001 (Reya et al., 2001). This hypothesis consists of 2 components. The first component postulates that normal tissue stem cells are the target for transforming mutations and successive mutations result in the formation of a tumor. The second component is that within every cancer a specific subset of cancer stem cells continuously gives rise to all the other cancer cells and only these cells within a tumor possess the ability to self-renew, continuously proliferate. Conflicting to the first component of the hypothesis, evidences indicate cancer stem cells can also arise from mutated progenitor cells rather than stem cells (Cheshier et al., 2009). In addition, mature cells such as Lymphocytes can lead to mouse T cell leukemia independently from HSCs (Yuan et al., 2006). For the latter component of cancer stem cell hypothesis, it is likely that the cancer stem cell hypothesis is applicable to some tumors but not to others. In hematopoiet ic and some solid malignancies, only 1 in 100 to 1 in 10 000 primary tumor cells are capable of reproducing the tumor in vivo, such as human breast cancer, human neuroepithelial tumors, head and neck squamous cell carcinomas, and colon cancer. But in melanoma, nearly 1 in 4 cells possessed the ability of proliferation and developing into cancer (Cheshier et al., 2009). Cancer stem cells and CNS stem cells were reviewed by Cheshier et al. (Cheshier et al., 2009). 1.4 Mesenchymal stem cells (MSCs) and their differentiation potential Bone marrow is composed of two main systems of cell, hematopoietic cells and the supporting stromal cells (Bianco et al., 2001). MSCs reside within the marrow, maintain a level of self-renewal, and give rise to progenitor cells that can differentiate into various lineages of tissue, including chondrocytes, osteoblasts, adipocytes, fibroblasts, marrow stroma, and other tissues of mesenchymal origin. The traditional opinion about the multipotent differentiation potential of MSCs was challenged by further studies. Interestingly, MSCs reside in a diverse host of tissues throughout the adult organism and possess the ability to ‘regenerate cell types specific for local tissues e.g. adipose, periosteum, synovial membrane, muscle, dermis, pericytes, blood, bone marrow, and most recently trabecular bone, reviewed by Tuan et al. (Tuan et al., 2003). Furthermore, in 2002, Jiang et al. reported a rare cell within human bone marrow mesenchymal stem cell cultures that can be expanded extensi vely without obvious senescence. This cell population can differentiate, not only into mesenchymal cells, but also cells with visceral mesoderm, neuroectoderm and endoderm characteristics in vitro. Most somatic cell types could be derived after this population of cells was injected into an early blastocyst (Jiang et al., 2002). These studies suggest mesenchymal stem cells maintained pluripotent properties. Chapter 2 Features of Articular Cartilage 2.1 Introduction Joint cartilage formed highly sophisticated structure during the evolutionary development. There have been considerable research interests related to the cartilage cells, chondrocytes. In the last decades these studies made cartilage the first and very successful tissue engineering treatment (Brittberg et al. 1994). 2.2 Categorization of cartilage tissues Cartilage tissue is categorised in three major types by different biochemical compositions and structures of their extracellular matrix (ECM). Elastic cartilage has a small concentration of proteoglycans (PGs), and a relatively high proportion of elastin fibres. It exists in the epiglottis, small laryngeal, the external ear, auditory tube, and the small bronchi, where it is generally required to resist bending forces. Fibrocartilage also possesses a small concentration of PGs, but far less elastins. The meniscus in the knee joint is made of fibrocartilage. Hyaline is the most widespread cartilage in the human body. It is resistant to compressive or tensile forces due to its special type II collagen fibril mesh filled with a high concentration of PGs. Hyaline cartilage can be found in the nose, trachea, bronchi, and synovial joints. In the latter case, it is termed as articular cartilage (Schulz and Bader, 2007). 2.3 Compositions of articular cartilage Chondrocytes contribute to only 1%- 5% of the tissue volume; the remaining 95%-99% being extracellular matrix (ECM). Chondrocytes sense and synthesize all necessary ECM components (Mollenhauer, 2008; Schulz and Bader, 2007). The ECM of articular cartilage consists of about 60-85% water and dissolved electrolytes. The solid framework is composed of collagens (10-20%), PGs (3-10%), noncollagenous proteins and glycoproteins. In articular cartilage, 95% of collagen in the ECM is type II collagen fibrils. The rest other types are collagen type IX and XI and a small fraction of types III, VI, XII and XIV. Normal articular cartilage does not present type I collagen, which is concerned with fibrous tissue. Unlike Type I and Type III collagens which form thick fibres and thin  ¬Ã‚ bres respectively, Type II collagen present in hyaline and elastic cartilages does not form  ¬Ã‚ bres. It forms very thin  ¬Ã‚ brils which are disposed as a loose mesh that strongly interacts with the groun d substance. Type II collagen provides tensile stiffness and strength to articular cartilage and constrains the swelling capacity generated by highly negatively charged glycosaminoglycans (GAGs) of the proteoglycans (PGs). The majority (50-85%) of the PG content in articular cartilage were presented by large molecule aggrecan. It consists of a protein backbone, the core protein, to which unbranched GAGs side chains of chondroitin sulphate (CS) and keratan sulfate (KS) are covalently attached (Figure 1.1). The composition of articular cartilage was extensively reviewed by Schulz and Bader (Schulz and Bader, 2007). Figure 1. Illustration of the extracellular matrix (ECM) organization of articular cartilage (Left) and the schematic sketches (Right) of the most relevant polysaccharides of proteoglycans (PGs) in articular cartilage. The PGs consist of a strand of hyaluronic acid (HA), to which a core protein is non-covalently attached. On the core protein, glycosaminoglycans (GAGs) such as keratan sulphate (KS) and chondroitin sulfate (CS) are covalently bound in a bottle brush fashion (Modified from Schulz and Bader, 2007 and Mow and Wang, 1999). 2.4 Low capacity of self-repair in articular cartilage The aneural and avascular nature of articular cartilage, coupled with its low cellularity, contribute to both the limited rate and incomplete nature of the repair process following damage (Heywood et al., 2004). The low mitotic potential of chondrocytes in vivo also contributes to its poor ability to undergo self-repair (Kuroda et al., 2007). Some researchers believe that cartilage lesions less than 3mm in diameter self-repair with normal hyaline-like cartilage (Revell and Athanasiou, 2009; Schulz and Bader, 2007). In animal studies, full thickness cartilage defects, extending into the subchondral bone, have been reported to heal with the formation of fibrous tissue, which contains relatively low amount of type II collagen and aggrecan, but a relatively high concentration of type I collagen which is not present in normal adult articular cartilage and accordingly exhibits impaired mechanical properties (Hjertquist et al., 1971). 2.5 Metabolism of articular cartilage Joint cartilage is supplied with nutrients and oxygen by the synovial fluid diffusion facilitated by compressive cyclic loading during joint movements which acts as a pumping function (Mollenhauer, 2008). Within synovial joints, oxygen supply to articular chondrocytes is very limited, from 7.5% at the superficial zone down to 1% oxygen tension at the deep zone. It is supposed to be even further decreased under pathological conditions, such as osteoarthritis (OA) or rheumatoid arthritis (RA). The metabolism of chondrocytes is largely glycolytic. Oxygen-dependent energy generated by oxidative phosphorylation is just a minor contributor to the overall energy in chondrocytes. Nevertheless, changes in O2 tension have profound effects on cell metabolism, phenotype, gene expression, and morphology, as well as response to, and production of, cytokines (Pfander and Gelse, 2007; Gibson et al., 2008). The most important component of this hypoxic response is mediated by transcription factor hypo xia-inducible factor-1 (HIF-1), which is present in most hypoxia inducible genes (Pfander and Gelse, 2007; Gibson et al., 2008). Moreover, the matrix turnover in articular cartilage is extremely slow. Proteoglycan turnover is up to 25 years. Collagen half-life is estimated to range from several decades up to 400 years (Mollenhauer, 2008). Chapter 3 Osteoarthritis (OA) 3.1 Prevalence Osteoarthritis (OA) is the most common form of arthritis. More than 40 million US American citizens (approximately 15% of the overall population of the USA) suffer from arthritis (Schulz and Bader, 2007). OA can occur in any joint but is most common in certain joints of the hand, knee, foot and hip. OA is the most common reason for total hip- and knee-joint replacement (Wieland et al., 2005). Among US adults 30 years of age or older, symptomatic disease in the knee occurs in approximately 6% and symptomatic hip osteoarthritis in roughly 3% (Felson and Zhang, 1998). 3.2 The symptoms and diagnosis The symptoms of OA include pain, stiffness and loss of function. OA can be monitored by radiography, magnetic resonance imaging (MRI), and arthroscopy, but radiographs are still considered the gold standard (Wieland et al., 2005). 3.3 The pathology of OA The pathologic characteristics of OA are the slowly developing degenerative breakdown of cartilage; the pathological changes in the bone, including osteophyte formation and thickening of the subchondral plate; the changes in the synovium such as inflammatory infiltrates; ligaments, which are often lax; and bridging muscle, which becomes weak. Many people with pathologic and radiographic evidence of osteoarthritis have no symptoms (Martel-Pelletier, 1999; Felson et al., 2000). A protease family of matrix metalloproteases (MMP) is responsible for the initial occurrence of cartilage matrix digestion. Of this family, collagenases, the stromelysins and the gelatinases are identified as being elevated in OA. Another group of MMP is localized at the cell membrane surface and is thus named membrane type MMP (MT-MMP) (Martel-Pelletier, 1999). Proinflamatory cytokines such as interleukin (IL)-1ÃŽ ², Tumor necrosis factor (TNF)-ÃŽ ±, IL-6, leukemic inhibitor factor (LIF) and IL-17 are first produced by the synovial membrane and then diffuse into the cartilage through the synovial fluid, where they activate the chondrocytes to produce proinflammatory cytokines. These proinflamatory cytokines are considered responsible for the catabolic pathological process (Martel-Pelletier, 1999). In OA cartilage, an increased level of an inducible form of nitric oxide synthase (iNOS) leads to a large amount of nitric oxide (NO) production (Pelletier et al., 2001). NO can inhibit the synthesis of cartilage matrix macromolecules such as aggrecans and can enhance MMP activity (Taskiran et al., 1994; Murrell et al., 1995). It is well stablished that proinflammatory cytokines such as IL-1ÃŽ ² act as the key mediators of cartilage breakdown and stimulate the release of inflammatory products (NO) and prostaglandin (PG)E2, via induction of iNOS and cyclo-oxygenase (COX)-2 enzymes (Chowdhury et al., 2008). 3.4 Risk factors Osteoarthritis is considered to be a systemic disease although severe joint injury may be sufficient to cause osteoarthritis. There are several systemic risk factors related to OA. (1) Age: Osteoarthritis increases with ages, the incidence and prevalence of disease increased 2- to 10-fold from 30 to 65 years of age and increased further thereafter in a community-based survey (Oliveria et al., 1995). (2) Hormonal status and bone density: women taking estrogen have a decreased prevalence of radiographic osteoarthritis (Nevitt et al., 1996). Before 50 years of age, the prevalence of osteoarthritis in most joints is higher in men than in women. After about age 50 years, women are more often affected with hand, foot, and knee osteoarthritis than men. In most studies, hip osteoarthritis is more frequent in men (van Saase et al., 1989). Evidence suggests an inverse relationship between osteoarthritis and osteoporosis (Felson et al., 2000). (3) Nutritional factors: evidence indicates that co ntinuous exposure to oxidants contributes to the development of many common age-related diseases, including osteoarthritis. McAlindon et al. reported a threefold reduction in risk for progressive radiographic osteoarthritis was observed in persons in the middle and highest tertile of vitamin C intake compared with those whose intake was in the lowest tertile (McAlindon et al., 1996a). Vitamin D intake was observed associated with the progression of OA although not associated with risk for new-onset radiographic osteoarthritis (McAlindon et al., 1996b; Lane et al., 1999). (4) Genetics: genetic factors account for at least 50% of cases of osteoarthritis in the hands and hips and a smaller percentage in the knees (Spector et al., 1996). Candidate genes for common forms of osteoarthritis include the vitamin D receptor gene, insulin-like growth factor I genes, cartilage oligomeric protein genes, and the HLA region (Felson et al., 2000). Local mechanical factors include the body weight and the pathological alterations of the mechanical environment of the joint. Persons who are overweight have a high prevalence of knee osteoarthritis (Felson et al., 1997). OA is also considered to be related to alterations in joint mechanical environments such as knee laxity, the displacement or rotation of the tibia with respect to the femur; proprioception, the conscious and unconscious perception of joint position and movement; knee alignment , knee position in reference to the hip and ankle (Felson et al., 2000). In addition, joint dysplasias, fractures of articular surfaces, and tears of menisci and ligaments that increase joint instability precede the development of osteoarthritis in a high percentage of affected joints. Risk factors for posttraumatic osteoarthritis include high body mass, high level of activity, residual joint instability or malalignment, and persistent articular surface incongruity (Buckwalter et al., 1997; Honkonen 1995). 3.5 Treatments The medicine treatment of OA was dominated by COX2 inhibitors (Flower 2003). The other medicines include glucosamine, chondroitin (McAlindon et al., 2000), and hyaluronic acid (Lo et al., 2003). In addition, both aerobic walking and muscle strengthening exercise reduce pain and disability from osteoarthritis (Roddy et al., 2005). Articular cartilage lesions, both of traumatic or pathological origin, do not heal spontaneously and often undergo progressive degeneration towards osteoarthritis (OA). The most frequently used treatments include the artificial joint replacement, mosaicplasty, marrow stimulation, and autologous condrocyte implantation (ACI) (Steinwachs et al., 2008). Total joint replacement is most commonly performed in people over 60 years of age. (NHS 2006; Brittberg et al., 1994) Mosaicplasty is an autologous osteochondral transplantation method through which cylindrical periosteum grafts are taken from periphery of the patellofemoral area which bears less weight, and transplanted to defective areas. This transplantation can be done with various diameters of grafts (Haklar et al., 2008; NHS, 2006). Marrow stimulation methods include arthroscopic surgery to smooth the surface of the damaged cartilage area; microfracture, drilling, abrasion. All marrow stimulation methods base on the penetration of the subchondral bone plate at the bottom of the cartilage defect. The outflowing bone marrow blood contains the mesenchymal stem cells which are stabilised by the clot formation in the defect. These pluripotent stem cells which are able to differentiate into fibrochondrocytes, result in fibrocartilage repair with varying amounts of type I, II and III collagen (Steinwachs et al., 2008). The ACI tissue engineering treatment will be discussed in the next chapter. Chapter 4 Tissue engineering and autologous chondrocyte implantation (ACI) 4.1 Overview of tissue engineering technologies Tissue engineering is defined as ‘‘the application of the principles and methods of engineering and the life sciences toward the fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and the development of biological substitutes to restore, maintain, or improve tissue function† (Langer and Vacanti, 1993). Three factors are considered as the principles of tissue engineering, including the utilization of biocompatible and mechanically suitable scaffolds, an appropriate cell source, and bioactive molecules to promote the differentiation and maturation of the cell type of interest (Song et al., 2004). Potential applications of tissue engineering are involved in the following fields: skin, cartilage, bone, cardiovascular diseases, organs (e.g. liver, pancreas, bladder, trachea and breast), central nervous system (e.g. spinal cord), and miscellaneous (e.g. soft tissue, ligaments). Although research is being carried out in all these fields, only few products have already entered the market. The most successful products up to now are: tissue engineered skin which is mainly used for wound cover, autologous chondrocyte implantation (ACI), and artificial bone graft (Hà ¼sing et al., 2003). 4.2 Autologous chondrocyte implantation (ACI) In 1984, a study in rabbits reported successful treatment of focal patellar defects with the use of ACI. One year after transplantation, newly formed cartilage-like tissue typically covered about 70 percent of the defect (Grande et al. 1989). In 1987, Brittberg firstly performed ACI in 23 people with deep cartilage defects in the knee. ACI is described as the following procedure: cartilage cells are taken from a minor load-bearing area on the upper medial femoral condyle of the damaged knee via an arthroscopic procedure, cultivated for four to six weeks in a laboratory and then, in open surgery, introduced back into the damaged area as a liquid or mesh-like transplant; at last, a periosteal flap sutured in place to secure the transplant (Figure 2; Brittberg et al., 1994). Genzyme Biosurgery with its product Carticel ® was the first company which introduced ACI into market and is the market leader in USA. Carticel ® is a classic ACI procedure using the periosteal cover (Hà ¼sing et al., 2008). Today the periosteum is often replaced by an artificial resorbable cover such as collagen I/III and hyaluronan membrane, such as ChondroGide or Restore (De Puy, Warzaw, Indiana) (Gooding et al., 2006; Jones and Peterson, 2006). Another new method uses chondrocytes cultured on a tri-dimensional (3D), biodegradable scaffold. This kind of scaffold, cut to the required size, is fixed into the lesion by anchoring stitches or its sticky nature. The 3D cell seeded scaffold eliminates the using of cover, thus simplifies the surgery procedure, saves the surgery time, and opens up the possibility of an arthroscopic surgery instead of the open surgery which causes more tissue damage. HYALOGRAFT from Italy is one of the European market leaders. It is a cartilage substit ute made of autologous chondrocytes delivered on a biocompatible 3D matrix, entirely composed of a derivative of hyaluronic acid (Marcacci et al. 2005). 4.3 Clinical results of ACI Brittberg studied the long-term durability of ACI-treated patients, 61 patients were followed for at least five years up to 11 years post-surgery (mean 7.4 years). After two years, 50 out of 61 patients were graded good-excellent. At the five to 11 years follow-up, 51 of the 61 were graded good-excellent (Brittberg et al., 2003). Since 1997 the year FDA approved ACI, this method has been widely performed in more than 20,000 patients all over the world. It has been reported to be effective in relieving clinical symptoms, such as pain and function (Wakitani et al., 2008). In a randomised controlled study, Knutsen et al. studied 80 patients who needed local cartilage repair with lesions on the femoral condyles of 2-10 cm2. There were no signi ¬Ã‚ cant differences in clinical results at 5 years follow-up (Knutsen et al., 2007). In another randomised controlled study that compared mosaicplasty with ACI, there was no significant difference in the number of patients who had an excellent or good clinical outcome at 1 year (69% [29/42] and 88% [51/58], respectively). In the subgroup of patients who had repairs to lesions of the medial femoral condyle, significantly more patients who had ACI had an excellent or good outcome (88% [21/24]) compared with those who had mosaicplasty (72% [21/29]) (p Clinical results of ACI were reviewed by Gikas 2009 (Gikas et al., 2009). Generally speaking, the outcomes of ACI treatment have been encouraging. However, most randomised controlled studies showed no significant difference between ACI and traditional treatments. 4.4 Limitations of ACI Microfracture is a very simple and low-cost procedure whereas ACI costs about $10 000 per patient. If ACI is not found to be more effective for improving articular cartilage repair than microfracture, the procedure will not be continued (Wakitani et al., 2008). There are several possible reasons to be blamed for the limitations of the traditional ACI procedure. The cell source in ACI is the cartilage tissue derived via an arthroscopic procedure from the low load-bearing area on the upper medial femoral condyle of the damaged knee. However, Wiseman et al. found the chondrocytes isolated from the low loaded area of the knee joint respond to mechanical stimulations in a distinct manner with the chondrocytes from the high loaded area, which suggests the traditional cell source of ACI may not provide enough mechanical response and may further lead to the insufficient mechanical properties of the repaired tissue (Wiseman et al. 2003). As cultured in monolayer, chondrocytes undergo a process of dedifferentiation and adopt a more  ¬Ã‚ broblast-like morphology, which is accompanied by an increase in proliferation and an altered phenotype. Type II collagen, the major protein produced by chondrocytes in articular cartilage, are down-regulated in the culture, while collagen types I and III are increased (Glowacki et al., 1983; Stocks et al., 2002; Benya et al., 1978). The agregating proteoglycan aggrecan of articular cartilage, is down-regulated during dedifferentiation and replaced by proteoglycans not speci ¬Ã‚ c to cartilage, such as versican (Glowacki et al., 1983; Stocks et al., 2002). Therefore, monolayer cultured chondrocytes do not express the origninal phenotype, and their ability to regenerate damaged cartilage tissue is impaired. Upon implantation, dedifferentiated cells may form a  ¬Ã‚ brous tissue expressing collagen type I that does not have appropriate mechanical properties, which may lead to deg radation and failure of the repair tissue (Brodkin et al., 2004). Chondrocytes grown in conditions that support their round shape, such as plating in high-density monolayer (Watt, 1988) and seeding in 3D structure (Benya and Shaffer, 1982) can maintain their differentiated phenotype much longer compared to cells spread in monolayer cultures. Although ACI can still be considered to be one of commonly form of repair of cartilage defects, it does have a number of scientific limitations. Some of those can be resolved using more comprehensive tissue engineered strategies which incorporates cells, scaffold materials and potentially biochemical, biomechanical and/or physical stimulation in a controlled bioreactor environment. 4.5 Tissue engineering strategies for ACI Chondrocytes derived from the low load bearing area of the knee joint respond in a distinct manner with the chondrocytes from the high loaded area. Chondrocytes cultured in monolayer have a dedifferentiation phenomenon as described above. In addition, the limitation of the transplant volume is always a major problem in autograft to be overcome (Kitaoka et al., 2001; Vinatier et. al, 2009). Accordingly, potential cell sources are widely studied for the future improvement of ACI approach, which will be discussed in Chapter 4. Seeding in 3D structures (Benya and Shaffer, 1982) can maintain chondrocytes differentiated phenotype. Ideally, cell scaffolds for tissue engineering should meet several design criteria: (1) The surface should permit cell adhension and growth, (2) neither the polymer nor its degradation products should provoke inflammation or toxicity when implanted in vivo, (3) the material should be reproducibly processable into three dimensional structures, (4) the porosity should be at least 90% in order to provide a high surface area for cell-polymer interactions, sufficient space of extracellular matrix regeneration, and minimal diffusional constraints during in vitro culture, (5) the scaffold should resorb once it has served its purpose of providing a template for the regenerating tissue, since foreign materials carry a permanent risk of inflammation, and (6) the scaffold degradation rate should be adjustable to match the rate of tissue regeneration by the cell type of interest (Freed et al., 1994). Synthetic materials such as poly (glycolic acid) (PGA), poly (lactic acid) (PLA), and poly (lactic-co-glycolic acid) (PLGA) have been investigated for use as cartilage tissue engineering scaffolds (Cima et al., 1991; Vacanti et al., 1991). Both, in vitro and in vivo studies have demonstrated these scaffold maintained the chondrocyte phenotype and the production of cartilage extracellular matrix (ECM) (Barnewitz et al., 2006; Kaps et al., 2006). Moreover, PLGA is used as a scaffold material for matrix-based autologous chondrocyte transplantation clinically (Ossendorf et al., 2007). Natural materials have also been investigated in the application of tissue engineering scaffolds in ACI. Collagen-based biomaterials are widely used in todays clinical practice (for example, haemostasis and cosmetic surgery). Collagen is also be commonly used as main components in tissue engineered skin products. Several commercial ACI products have used collagenous membraneas as the replacement for the periosteum to close the defect, such as ChondroGide or Restore (De Puy, Warzaw, Indiana) (Cicuttini et al., 1996; Jones and Peterson, 2006). The combination of type I collagen with GAG in scaffolds had a positive effect on chondrocyte phenotype (van Susante et al., 2001). Hyaluronic acid is a non-sulphated GAG that makes up a large proportion of cartilage extracellular matrix (Schulz and Bader, 2007). Matrices composed of hyaluronan have been frequently used as carriers for chondrocytes. Facchini et al. con ¬Ã‚ rms the hyaluronan derivative scaffold Hyaff  ®11 as a suitable scaff old both for chondrocytes and mesenchymal stem cells for the treatment of articular cartilage defects in their study (Facchini et al., 2006). Sugar-based natural polymers such as chitosan, alginate and agarose can be formulated as hydrogels and in some cases sponges or pads. Although these materials are extensively used in in vitro research, their role in in vivo cartilage reconstruction is still limited (Stoop, 2008). Growth factors are proved to be able to promote the formation of new cartilage tissue in both explants and engineered constructs. Insulin-like growth factor-I (IGF-I), transforming growth factor-ÃŽ ²1 (TGF-ÃŽ ²1) increases, basic fibroblast growth factor (bFGF) can stimulate cell proliferation and/or biosynthesis in chondrocytes which were Immune Privilege of Tissue Engineered Articular Cartilage Immune Privilege of Tissue Engineered Articular Cartilage The immune privilege of tissue engineered articular cartilage derived from mouse adult mesenchymal stem cells and the potential of tissue engineered cartilage as a gene delivery method Chapter 1 Stem cell biology 1.1 Categorization of stem cells Stem cells are generally defined as cells possessing the following 3 characteristics: (1) self-renewal, (2) the ability to produce all cell types made in that tissue, and (3) the ability to do so for a significant portion of the life of the host (Alberts et al., 1989; Reya et al., 2001), while progenitor cells are capable only of multi-lineage differentiation without self-renewal (Weissman, 2000). Stem cells can be classified by their ability to differentiate. The most primitive, totipotent stem cells have the ability to divide and produce all the differentiated cells in an organism, including both the embryonic and extraembryonic tissues of an organism. Totipotent stem cells include the fertilized egg and the cells produced by the initial divisions of it. In mammals, these cell divisions result in an implant in the uterus called the blastocyst. The blastocyst contains an outer sphere of trophoblast cells. Trophoblast cells are capable of implanting into the uterus and helping the form of placenta which provides nutrients to the embryo. Within the blastocyst are 10 to 20 pluripotent cells called the inner cell mass. In mammalian uterus, these inner mass cells will participate in the production of all tissues and organs of the developing embryo, then fetus, then born organism. Such pluripotent cells can produce any differentiated cells in the body, but are usually unable to for m the trophoblast cells. The best-known pluripotent stem cell is the embryonic stem (ES) cell, which are obtained from the inner cell mass of the blastocyst and exist for only a brief stage of embryonic development. The last major class of stem cells, multipotent stem cells, gives rise to a limited number of cell types which are responsible for organ growth and renewal such as neural stem cells, skin stem cells and haematopoietic stem cells (HSCs) (Cheshier et al., 2009). 1.2 Selected milestones of stem cell research In 1981, Martin isolated a pluripotent stem cell line from early mouse embryos (Martin, 1981). Wilmut in 1996 first cloned a mammal, a lamb named Dolly by transferring nuclear from the adult mammary gland cell to an enucleated unfertilized egg (Wilmut et al., 1997). In 1998, Thomson obtained the first human embryonic stem cell line from human blastocysts (Thomson et al., 1998). In 2001, President Bush banned scientists from using federal funds to study stem cells from sources other than those that had already been grown because of the ethical concerns. To avoid ethical dispute over the use of human embryonic cells for research purposes, many efforts have been taken on obtaining pluripotent stem cells from differentiated donor cells. In 2006, Yamanaka find a way to obtain pluripotent cells by reprogramming the nucleus of adult mice skin cells (Takahashi and Yamanaka, 2006). Such cells are now known as induced pluripotent stem (iPS) cells. 1.3 A brief introduction of several types of multipotent stem cell The best known multipotent stem cells are haematopoietic stem cells (HSCs), that give rise to all the blood cell types including myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells). HSCs are vital elements in bone-marrow transplantation, which has already been used extensively in therapeutic settings (Reya et al., 2001). In the long-term culture systems, human and rodent Central Neural System (CNS) cells maintain the capacity to produce the three main mature cell classes of the CNS: neurons, astrocytes, and oligodendrocytes, which suggest stem cells and/or progenitors exist and can survive in the culture medium (Weiss et al., 1996; Carpenter et al., 1999). In 2000, Human CNS stem cells (hCNS-SCs) have been successfully isolated by FACs (Uchida et al., 2000). Cancer stem cell hypothesis was proposed by Reya 2001 (Reya et al., 2001). This hypothesis consists of 2 components. The first component postulates that normal tissue stem cells are the target for transforming mutations and successive mutations result in the formation of a tumor. The second component is that within every cancer a specific subset of cancer stem cells continuously gives rise to all the other cancer cells and only these cells within a tumor possess the ability to self-renew, continuously proliferate. Conflicting to the first component of the hypothesis, evidences indicate cancer stem cells can also arise from mutated progenitor cells rather than stem cells (Cheshier et al., 2009). In addition, mature cells such as Lymphocytes can lead to mouse T cell leukemia independently from HSCs (Yuan et al., 2006). For the latter component of cancer stem cell hypothesis, it is likely that the cancer stem cell hypothesis is applicable to some tumors but not to others. In hematopoiet ic and some solid malignancies, only 1 in 100 to 1 in 10 000 primary tumor cells are capable of reproducing the tumor in vivo, such as human breast cancer, human neuroepithelial tumors, head and neck squamous cell carcinomas, and colon cancer. But in melanoma, nearly 1 in 4 cells possessed the ability of proliferation and developing into cancer (Cheshier et al., 2009). Cancer stem cells and CNS stem cells were reviewed by Cheshier et al. (Cheshier et al., 2009). 1.4 Mesenchymal stem cells (MSCs) and their differentiation potential Bone marrow is composed of two main systems of cell, hematopoietic cells and the supporting stromal cells (Bianco et al., 2001). MSCs reside within the marrow, maintain a level of self-renewal, and give rise to progenitor cells that can differentiate into various lineages of tissue, including chondrocytes, osteoblasts, adipocytes, fibroblasts, marrow stroma, and other tissues of mesenchymal origin. The traditional opinion about the multipotent differentiation potential of MSCs was challenged by further studies. Interestingly, MSCs reside in a diverse host of tissues throughout the adult organism and possess the ability to ‘regenerate cell types specific for local tissues e.g. adipose, periosteum, synovial membrane, muscle, dermis, pericytes, blood, bone marrow, and most recently trabecular bone, reviewed by Tuan et al. (Tuan et al., 2003). Furthermore, in 2002, Jiang et al. reported a rare cell within human bone marrow mesenchymal stem cell cultures that can be expanded extensi vely without obvious senescence. This cell population can differentiate, not only into mesenchymal cells, but also cells with visceral mesoderm, neuroectoderm and endoderm characteristics in vitro. Most somatic cell types could be derived after this population of cells was injected into an early blastocyst (Jiang et al., 2002). These studies suggest mesenchymal stem cells maintained pluripotent properties. Chapter 2 Features of Articular Cartilage 2.1 Introduction Joint cartilage formed highly sophisticated structure during the evolutionary development. There have been considerable research interests related to the cartilage cells, chondrocytes. In the last decades these studies made cartilage the first and very successful tissue engineering treatment (Brittberg et al. 1994). 2.2 Categorization of cartilage tissues Cartilage tissue is categorised in three major types by different biochemical compositions and structures of their extracellular matrix (ECM). Elastic cartilage has a small concentration of proteoglycans (PGs), and a relatively high proportion of elastin fibres. It exists in the epiglottis, small laryngeal, the external ear, auditory tube, and the small bronchi, where it is generally required to resist bending forces. Fibrocartilage also possesses a small concentration of PGs, but far less elastins. The meniscus in the knee joint is made of fibrocartilage. Hyaline is the most widespread cartilage in the human body. It is resistant to compressive or tensile forces due to its special type II collagen fibril mesh filled with a high concentration of PGs. Hyaline cartilage can be found in the nose, trachea, bronchi, and synovial joints. In the latter case, it is termed as articular cartilage (Schulz and Bader, 2007). 2.3 Compositions of articular cartilage Chondrocytes contribute to only 1%- 5% of the tissue volume; the remaining 95%-99% being extracellular matrix (ECM). Chondrocytes sense and synthesize all necessary ECM components (Mollenhauer, 2008; Schulz and Bader, 2007). The ECM of articular cartilage consists of about 60-85% water and dissolved electrolytes. The solid framework is composed of collagens (10-20%), PGs (3-10%), noncollagenous proteins and glycoproteins. In articular cartilage, 95% of collagen in the ECM is type II collagen fibrils. The rest other types are collagen type IX and XI and a small fraction of types III, VI, XII and XIV. Normal articular cartilage does not present type I collagen, which is concerned with fibrous tissue. Unlike Type I and Type III collagens which form thick fibres and thin  ¬Ã‚ bres respectively, Type II collagen present in hyaline and elastic cartilages does not form  ¬Ã‚ bres. It forms very thin  ¬Ã‚ brils which are disposed as a loose mesh that strongly interacts with the groun d substance. Type II collagen provides tensile stiffness and strength to articular cartilage and constrains the swelling capacity generated by highly negatively charged glycosaminoglycans (GAGs) of the proteoglycans (PGs). The majority (50-85%) of the PG content in articular cartilage were presented by large molecule aggrecan. It consists of a protein backbone, the core protein, to which unbranched GAGs side chains of chondroitin sulphate (CS) and keratan sulfate (KS) are covalently attached (Figure 1.1). The composition of articular cartilage was extensively reviewed by Schulz and Bader (Schulz and Bader, 2007). Figure 1. Illustration of the extracellular matrix (ECM) organization of articular cartilage (Left) and the schematic sketches (Right) of the most relevant polysaccharides of proteoglycans (PGs) in articular cartilage. The PGs consist of a strand of hyaluronic acid (HA), to which a core protein is non-covalently attached. On the core protein, glycosaminoglycans (GAGs) such as keratan sulphate (KS) and chondroitin sulfate (CS) are covalently bound in a bottle brush fashion (Modified from Schulz and Bader, 2007 and Mow and Wang, 1999). 2.4 Low capacity of self-repair in articular cartilage The aneural and avascular nature of articular cartilage, coupled with its low cellularity, contribute to both the limited rate and incomplete nature of the repair process following damage (Heywood et al., 2004). The low mitotic potential of chondrocytes in vivo also contributes to its poor ability to undergo self-repair (Kuroda et al., 2007). Some researchers believe that cartilage lesions less than 3mm in diameter self-repair with normal hyaline-like cartilage (Revell and Athanasiou, 2009; Schulz and Bader, 2007). In animal studies, full thickness cartilage defects, extending into the subchondral bone, have been reported to heal with the formation of fibrous tissue, which contains relatively low amount of type II collagen and aggrecan, but a relatively high concentration of type I collagen which is not present in normal adult articular cartilage and accordingly exhibits impaired mechanical properties (Hjertquist et al., 1971). 2.5 Metabolism of articular cartilage Joint cartilage is supplied with nutrients and oxygen by the synovial fluid diffusion facilitated by compressive cyclic loading during joint movements which acts as a pumping function (Mollenhauer, 2008). Within synovial joints, oxygen supply to articular chondrocytes is very limited, from 7.5% at the superficial zone down to 1% oxygen tension at the deep zone. It is supposed to be even further decreased under pathological conditions, such as osteoarthritis (OA) or rheumatoid arthritis (RA). The metabolism of chondrocytes is largely glycolytic. Oxygen-dependent energy generated by oxidative phosphorylation is just a minor contributor to the overall energy in chondrocytes. Nevertheless, changes in O2 tension have profound effects on cell metabolism, phenotype, gene expression, and morphology, as well as response to, and production of, cytokines (Pfander and Gelse, 2007; Gibson et al., 2008). The most important component of this hypoxic response is mediated by transcription factor hypo xia-inducible factor-1 (HIF-1), which is present in most hypoxia inducible genes (Pfander and Gelse, 2007; Gibson et al., 2008). Moreover, the matrix turnover in articular cartilage is extremely slow. Proteoglycan turnover is up to 25 years. Collagen half-life is estimated to range from several decades up to 400 years (Mollenhauer, 2008). Chapter 3 Osteoarthritis (OA) 3.1 Prevalence Osteoarthritis (OA) is the most common form of arthritis. More than 40 million US American citizens (approximately 15% of the overall population of the USA) suffer from arthritis (Schulz and Bader, 2007). OA can occur in any joint but is most common in certain joints of the hand, knee, foot and hip. OA is the most common reason for total hip- and knee-joint replacement (Wieland et al., 2005). Among US adults 30 years of age or older, symptomatic disease in the knee occurs in approximately 6% and symptomatic hip osteoarthritis in roughly 3% (Felson and Zhang, 1998). 3.2 The symptoms and diagnosis The symptoms of OA include pain, stiffness and loss of function. OA can be monitored by radiography, magnetic resonance imaging (MRI), and arthroscopy, but radiographs are still considered the gold standard (Wieland et al., 2005). 3.3 The pathology of OA The pathologic characteristics of OA are the slowly developing degenerative breakdown of cartilage; the pathological changes in the bone, including osteophyte formation and thickening of the subchondral plate; the changes in the synovium such as inflammatory infiltrates; ligaments, which are often lax; and bridging muscle, which becomes weak. Many people with pathologic and radiographic evidence of osteoarthritis have no symptoms (Martel-Pelletier, 1999; Felson et al., 2000). A protease family of matrix metalloproteases (MMP) is responsible for the initial occurrence of cartilage matrix digestion. Of this family, collagenases, the stromelysins and the gelatinases are identified as being elevated in OA. Another group of MMP is localized at the cell membrane surface and is thus named membrane type MMP (MT-MMP) (Martel-Pelletier, 1999). Proinflamatory cytokines such as interleukin (IL)-1ÃŽ ², Tumor necrosis factor (TNF)-ÃŽ ±, IL-6, leukemic inhibitor factor (LIF) and IL-17 are first produced by the synovial membrane and then diffuse into the cartilage through the synovial fluid, where they activate the chondrocytes to produce proinflammatory cytokines. These proinflamatory cytokines are considered responsible for the catabolic pathological process (Martel-Pelletier, 1999). In OA cartilage, an increased level of an inducible form of nitric oxide synthase (iNOS) leads to a large amount of nitric oxide (NO) production (Pelletier et al., 2001). NO can inhibit the synthesis of cartilage matrix macromolecules such as aggrecans and can enhance MMP activity (Taskiran et al., 1994; Murrell et al., 1995). It is well stablished that proinflammatory cytokines such as IL-1ÃŽ ² act as the key mediators of cartilage breakdown and stimulate the release of inflammatory products (NO) and prostaglandin (PG)E2, via induction of iNOS and cyclo-oxygenase (COX)-2 enzymes (Chowdhury et al., 2008). 3.4 Risk factors Osteoarthritis is considered to be a systemic disease although severe joint injury may be sufficient to cause osteoarthritis. There are several systemic risk factors related to OA. (1) Age: Osteoarthritis increases with ages, the incidence and prevalence of disease increased 2- to 10-fold from 30 to 65 years of age and increased further thereafter in a community-based survey (Oliveria et al., 1995). (2) Hormonal status and bone density: women taking estrogen have a decreased prevalence of radiographic osteoarthritis (Nevitt et al., 1996). Before 50 years of age, the prevalence of osteoarthritis in most joints is higher in men than in women. After about age 50 years, women are more often affected with hand, foot, and knee osteoarthritis than men. In most studies, hip osteoarthritis is more frequent in men (van Saase et al., 1989). Evidence suggests an inverse relationship between osteoarthritis and osteoporosis (Felson et al., 2000). (3) Nutritional factors: evidence indicates that co ntinuous exposure to oxidants contributes to the development of many common age-related diseases, including osteoarthritis. McAlindon et al. reported a threefold reduction in risk for progressive radiographic osteoarthritis was observed in persons in the middle and highest tertile of vitamin C intake compared with those whose intake was in the lowest tertile (McAlindon et al., 1996a). Vitamin D intake was observed associated with the progression of OA although not associated with risk for new-onset radiographic osteoarthritis (McAlindon et al., 1996b; Lane et al., 1999). (4) Genetics: genetic factors account for at least 50% of cases of osteoarthritis in the hands and hips and a smaller percentage in the knees (Spector et al., 1996). Candidate genes for common forms of osteoarthritis include the vitamin D receptor gene, insulin-like growth factor I genes, cartilage oligomeric protein genes, and the HLA region (Felson et al., 2000). Local mechanical factors include the body weight and the pathological alterations of the mechanical environment of the joint. Persons who are overweight have a high prevalence of knee osteoarthritis (Felson et al., 1997). OA is also considered to be related to alterations in joint mechanical environments such as knee laxity, the displacement or rotation of the tibia with respect to the femur; proprioception, the conscious and unconscious perception of joint position and movement; knee alignment , knee position in reference to the hip and ankle (Felson et al., 2000). In addition, joint dysplasias, fractures of articular surfaces, and tears of menisci and ligaments that increase joint instability precede the development of osteoarthritis in a high percentage of affected joints. Risk factors for posttraumatic osteoarthritis include high body mass, high level of activity, residual joint instability or malalignment, and persistent articular surface incongruity (Buckwalter et al., 1997; Honkonen 1995). 3.5 Treatments The medicine treatment of OA was dominated by COX2 inhibitors (Flower 2003). The other medicines include glucosamine, chondroitin (McAlindon et al., 2000), and hyaluronic acid (Lo et al., 2003). In addition, both aerobic walking and muscle strengthening exercise reduce pain and disability from osteoarthritis (Roddy et al., 2005). Articular cartilage lesions, both of traumatic or pathological origin, do not heal spontaneously and often undergo progressive degeneration towards osteoarthritis (OA). The most frequently used treatments include the artificial joint replacement, mosaicplasty, marrow stimulation, and autologous condrocyte implantation (ACI) (Steinwachs et al., 2008). Total joint replacement is most commonly performed in people over 60 years of age. (NHS 2006; Brittberg et al., 1994) Mosaicplasty is an autologous osteochondral transplantation method through which cylindrical periosteum grafts are taken from periphery of the patellofemoral area which bears less weight, and transplanted to defective areas. This transplantation can be done with various diameters of grafts (Haklar et al., 2008; NHS, 2006). Marrow stimulation methods include arthroscopic surgery to smooth the surface of the damaged cartilage area; microfracture, drilling, abrasion. All marrow stimulation methods base on the penetration of the subchondral bone plate at the bottom of the cartilage defect. The outflowing bone marrow blood contains the mesenchymal stem cells which are stabilised by the clot formation in the defect. These pluripotent stem cells which are able to differentiate into fibrochondrocytes, result in fibrocartilage repair with varying amounts of type I, II and III collagen (Steinwachs et al., 2008). The ACI tissue engineering treatment will be discussed in the next chapter. Chapter 4 Tissue engineering and autologous chondrocyte implantation (ACI) 4.1 Overview of tissue engineering technologies Tissue engineering is defined as ‘‘the application of the principles and methods of engineering and the life sciences toward the fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and the development of biological substitutes to restore, maintain, or improve tissue function† (Langer and Vacanti, 1993). Three factors are considered as the principles of tissue engineering, including the utilization of biocompatible and mechanically suitable scaffolds, an appropriate cell source, and bioactive molecules to promote the differentiation and maturation of the cell type of interest (Song et al., 2004). Potential applications of tissue engineering are involved in the following fields: skin, cartilage, bone, cardiovascular diseases, organs (e.g. liver, pancreas, bladder, trachea and breast), central nervous system (e.g. spinal cord), and miscellaneous (e.g. soft tissue, ligaments). Although research is being carried out in all these fields, only few products have already entered the market. The most successful products up to now are: tissue engineered skin which is mainly used for wound cover, autologous chondrocyte implantation (ACI), and artificial bone graft (Hà ¼sing et al., 2003). 4.2 Autologous chondrocyte implantation (ACI) In 1984, a study in rabbits reported successful treatment of focal patellar defects with the use of ACI. One year after transplantation, newly formed cartilage-like tissue typically covered about 70 percent of the defect (Grande et al. 1989). In 1987, Brittberg firstly performed ACI in 23 people with deep cartilage defects in the knee. ACI is described as the following procedure: cartilage cells are taken from a minor load-bearing area on the upper medial femoral condyle of the damaged knee via an arthroscopic procedure, cultivated for four to six weeks in a laboratory and then, in open surgery, introduced back into the damaged area as a liquid or mesh-like transplant; at last, a periosteal flap sutured in place to secure the transplant (Figure 2; Brittberg et al., 1994). Genzyme Biosurgery with its product Carticel ® was the first company which introduced ACI into market and is the market leader in USA. Carticel ® is a classic ACI procedure using the periosteal cover (Hà ¼sing et al., 2008). Today the periosteum is often replaced by an artificial resorbable cover such as collagen I/III and hyaluronan membrane, such as ChondroGide or Restore (De Puy, Warzaw, Indiana) (Gooding et al., 2006; Jones and Peterson, 2006). Another new method uses chondrocytes cultured on a tri-dimensional (3D), biodegradable scaffold. This kind of scaffold, cut to the required size, is fixed into the lesion by anchoring stitches or its sticky nature. The 3D cell seeded scaffold eliminates the using of cover, thus simplifies the surgery procedure, saves the surgery time, and opens up the possibility of an arthroscopic surgery instead of the open surgery which causes more tissue damage. HYALOGRAFT from Italy is one of the European market leaders. It is a cartilage substit ute made of autologous chondrocytes delivered on a biocompatible 3D matrix, entirely composed of a derivative of hyaluronic acid (Marcacci et al. 2005). 4.3 Clinical results of ACI Brittberg studied the long-term durability of ACI-treated patients, 61 patients were followed for at least five years up to 11 years post-surgery (mean 7.4 years). After two years, 50 out of 61 patients were graded good-excellent. At the five to 11 years follow-up, 51 of the 61 were graded good-excellent (Brittberg et al., 2003). Since 1997 the year FDA approved ACI, this method has been widely performed in more than 20,000 patients all over the world. It has been reported to be effective in relieving clinical symptoms, such as pain and function (Wakitani et al., 2008). In a randomised controlled study, Knutsen et al. studied 80 patients who needed local cartilage repair with lesions on the femoral condyles of 2-10 cm2. There were no signi ¬Ã‚ cant differences in clinical results at 5 years follow-up (Knutsen et al., 2007). In another randomised controlled study that compared mosaicplasty with ACI, there was no significant difference in the number of patients who had an excellent or good clinical outcome at 1 year (69% [29/42] and 88% [51/58], respectively). In the subgroup of patients who had repairs to lesions of the medial femoral condyle, significantly more patients who had ACI had an excellent or good outcome (88% [21/24]) compared with those who had mosaicplasty (72% [21/29]) (p Clinical results of ACI were reviewed by Gikas 2009 (Gikas et al., 2009). Generally speaking, the outcomes of ACI treatment have been encouraging. However, most randomised controlled studies showed no significant difference between ACI and traditional treatments. 4.4 Limitations of ACI Microfracture is a very simple and low-cost procedure whereas ACI costs about $10 000 per patient. If ACI is not found to be more effective for improving articular cartilage repair than microfracture, the procedure will not be continued (Wakitani et al., 2008). There are several possible reasons to be blamed for the limitations of the traditional ACI procedure. The cell source in ACI is the cartilage tissue derived via an arthroscopic procedure from the low load-bearing area on the upper medial femoral condyle of the damaged knee. However, Wiseman et al. found the chondrocytes isolated from the low loaded area of the knee joint respond to mechanical stimulations in a distinct manner with the chondrocytes from the high loaded area, which suggests the traditional cell source of ACI may not provide enough mechanical response and may further lead to the insufficient mechanical properties of the repaired tissue (Wiseman et al. 2003). As cultured in monolayer, chondrocytes undergo a process of dedifferentiation and adopt a more  ¬Ã‚ broblast-like morphology, which is accompanied by an increase in proliferation and an altered phenotype. Type II collagen, the major protein produced by chondrocytes in articular cartilage, are down-regulated in the culture, while collagen types I and III are increased (Glowacki et al., 1983; Stocks et al., 2002; Benya et al., 1978). The agregating proteoglycan aggrecan of articular cartilage, is down-regulated during dedifferentiation and replaced by proteoglycans not speci ¬Ã‚ c to cartilage, such as versican (Glowacki et al., 1983; Stocks et al., 2002). Therefore, monolayer cultured chondrocytes do not express the origninal phenotype, and their ability to regenerate damaged cartilage tissue is impaired. Upon implantation, dedifferentiated cells may form a  ¬Ã‚ brous tissue expressing collagen type I that does not have appropriate mechanical properties, which may lead to deg radation and failure of the repair tissue (Brodkin et al., 2004). Chondrocytes grown in conditions that support their round shape, such as plating in high-density monolayer (Watt, 1988) and seeding in 3D structure (Benya and Shaffer, 1982) can maintain their differentiated phenotype much longer compared to cells spread in monolayer cultures. Although ACI can still be considered to be one of commonly form of repair of cartilage defects, it does have a number of scientific limitations. Some of those can be resolved using more comprehensive tissue engineered strategies which incorporates cells, scaffold materials and potentially biochemical, biomechanical and/or physical stimulation in a controlled bioreactor environment. 4.5 Tissue engineering strategies for ACI Chondrocytes derived from the low load bearing area of the knee joint respond in a distinct manner with the chondrocytes from the high loaded area. Chondrocytes cultured in monolayer have a dedifferentiation phenomenon as described above. In addition, the limitation of the transplant volume is always a major problem in autograft to be overcome (Kitaoka et al., 2001; Vinatier et. al, 2009). Accordingly, potential cell sources are widely studied for the future improvement of ACI approach, which will be discussed in Chapter 4. Seeding in 3D structures (Benya and Shaffer, 1982) can maintain chondrocytes differentiated phenotype. Ideally, cell scaffolds for tissue engineering should meet several design criteria: (1) The surface should permit cell adhension and growth, (2) neither the polymer nor its degradation products should provoke inflammation or toxicity when implanted in vivo, (3) the material should be reproducibly processable into three dimensional structures, (4) the porosity should be at least 90% in order to provide a high surface area for cell-polymer interactions, sufficient space of extracellular matrix regeneration, and minimal diffusional constraints during in vitro culture, (5) the scaffold should resorb once it has served its purpose of providing a template for the regenerating tissue, since foreign materials carry a permanent risk of inflammation, and (6) the scaffold degradation rate should be adjustable to match the rate of tissue regeneration by the cell type of interest (Freed et al., 1994). Synthetic materials such as poly (glycolic acid) (PGA), poly (lactic acid) (PLA), and poly (lactic-co-glycolic acid) (PLGA) have been investigated for use as cartilage tissue engineering scaffolds (Cima et al., 1991; Vacanti et al., 1991). Both, in vitro and in vivo studies have demonstrated these scaffold maintained the chondrocyte phenotype and the production of cartilage extracellular matrix (ECM) (Barnewitz et al., 2006; Kaps et al., 2006). Moreover, PLGA is used as a scaffold material for matrix-based autologous chondrocyte transplantation clinically (Ossendorf et al., 2007). Natural materials have also been investigated in the application of tissue engineering scaffolds in ACI. Collagen-based biomaterials are widely used in todays clinical practice (for example, haemostasis and cosmetic surgery). Collagen is also be commonly used as main components in tissue engineered skin products. Several commercial ACI products have used collagenous membraneas as the replacement for the periosteum to close the defect, such as ChondroGide or Restore (De Puy, Warzaw, Indiana) (Cicuttini et al., 1996; Jones and Peterson, 2006). The combination of type I collagen with GAG in scaffolds had a positive effect on chondrocyte phenotype (van Susante et al., 2001). Hyaluronic acid is a non-sulphated GAG that makes up a large proportion of cartilage extracellular matrix (Schulz and Bader, 2007). Matrices composed of hyaluronan have been frequently used as carriers for chondrocytes. Facchini et al. con ¬Ã‚ rms the hyaluronan derivative scaffold Hyaff  ®11 as a suitable scaff old both for chondrocytes and mesenchymal stem cells for the treatment of articular cartilage defects in their study (Facchini et al., 2006). Sugar-based natural polymers such as chitosan, alginate and agarose can be formulated as hydrogels and in some cases sponges or pads. Although these materials are extensively used in in vitro research, their role in in vivo cartilage reconstruction is still limited (Stoop, 2008). Growth factors are proved to be able to promote the formation of new cartilage tissue in both explants and engineered constructs. Insulin-like growth factor-I (IGF-I), transforming growth factor-ÃŽ ²1 (TGF-ÃŽ ²1) increases, basic fibroblast growth factor (bFGF) can stimulate cell proliferation and/or biosynthesis in chondrocytes which were