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Stem Cell Therapy: Not Quite Ready Yet for Tendon Disorders
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Posted on: 11/10/2010
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Many people support the use of stem cell research but government regulation has slowed the process of study in this area. What's the evidence so far that stem cell therapy could benefit someone with tendinosis? That is the focus of this meta-analysis.
Let's define some terms here to help explain what is being studied and the results reported so far. First, tendinosis is a term used to describe tendons that developed a painful tendinitis (acute inflammation) that just didn't heal and became a chronic condition. The body attempted to organize a healing response. But instead of making new, healthy tendon cells to replace the damaged cells, the tendon tissue became thick with disorganized fibers. The already damaged tendon, now further weakened, fails to heal and may even go on to tear even more.
Next, a meta-analysis study tells us the authors found every article possible on the topic and reviewed them for design, quality, and content. Those articles that passed a pre-established set of criteria were then analyzed and summarized. And finally, just exactly what are stem cells?
Stem cells are the basic cells that can form any other type of cell such as bone cells, tenocytes (tendon cells), myocytes (muscle cells), brain cells and so forth. In humans, there are two basic types of stem cells: 1) embryonic stem cells taken from the umbilical cord of newborns or cells of fetuses that have died before being born and 2) adult stem cells that are found in adult tissues. In a developing embryo, stem cells are designed so they can form all the different tissues in the body. In adults, stem cells act as a repair system for the body when something wears out or is damaged due to injury or disease.
Scientists have figured out a way to harvest stem cells from fat, skin, tendon, and muscle then take it to the lab where they can multiply the sample and grow more cells. When there are enough cells to do the repair job needed, they are injected into the damaged area (e.g., tendon). That sounds simple enough but in fact, there are major barriers to the process.
For example, it takes time to generate more tissue in a lab setting. The lab has to have expensive, specialized equipment to do this type of work. Meanwhile, the injured athlete or other patient is waiting and the window of opportunity for healing is getting smaller and smaller. Transporting the cells comes with a lot of potential problems. No one is quite sure how well the cells travel from lab to patient. Questions have been asked about the need to freeze the cells in order to keep them preserved for use. If they could be frozen ahead of time and ready at a moment's notice, the donor cells could be used right away at the time of injury.
None of these problems can be solved easily or quickly with the current government regulations in place. That's why some scientists have started looking elsewhere for solutions to the problem (e.g., whole blood, platelet-rich plasma). But for those who have stuck with stem cell therapy, here's what the authors have found reported in the literature:
There are more animal studies than human studies in the area of stem cell research for tendons. The application to racehorses who need spring and speed has developed much faster than in humans (athletes). Clinical trials in humans are definitely needed before stem cell therapy becomes a reality for tendon problems.
Even though the exact mechanism by which stem cell therapy works remains somewhat of a mystery, the limited studies done so far in the area of tendon healing are very encouraging.
Stem cells from skin and adipose (fat cells) are easy to harvest, plentiful, and seem to work well in tendon healing.
Efforts are being made to find a way to use stem cells from skin and bone to replace/rebuild rotator cuff tears (a common injury in humans). Most of the results have been positive but the studies have been done on mice, rabbits, and pigs.
Pharmaceutical research and development is focused on finding a way to provide off-the-shelf (ready-to-use) sources of stem cells to avoid the time and expense of harvesting and expanding cells retrieved from the injured athlete (or patient).
In summary, there are over 1000 studies published in the area of stem cell research for tendon healing. Restricting the search to those written in English narrowed the pool to 379 articles. From the information provided, the authors were able to create a table summarizing different types of cells used in tissue engineering for tendons. Advantages and disadvantages of each type are listed in greater detail than presented here.
There is every reason to believe from these reported results that although hampered by government regulation, advances are being made in the area of cell therapy and tissue engineering. Even with obstacles, the ingenuity of scientists to think outside the box has moved the field of study ahead significantly in the last 20 years. Evidence is still fairly limited and long-term results are absent for now. This may change in time with more resources dedicated in the future to stem cell therapy.
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References:
Haron Obaid, MBChB, FRCS, FRCR, and David Connell, MB BS, MMed, FRANZCR. Cell Therapy in Tendon Disorders. In The American Journal of Sports Medicine. October 2010. Vol. 38. No. 10. Pp. 2123-2132.
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*Disclaimer:*The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic. |
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