Stem cells, undifferentiated or poorly differentiated cells obtained from fetal or other tissues, show great promise in treating many different diseases. Due to ethical concerns and the difficulty of obtaining fetal stem cells, scientists are trying to use patients' own cells instead. Stem cells derived from the patient, also called autologous cells, are slightly more specialized than the very primitive stem cells in fetal tissue, but they are easier to obtain and certainly more plentiful. Several studies indicate that these cells offer great hope in treating disease. Using autologous cells eliminates the risk of rejection, graft versus host reaction or disease transmission and avoids ethical concerns.
Stem cells from embryos are pluripotent; that is, they can transform into any type of tissue. Adults have stem cells in various organs, but these are more specialized, and until recently scientist were of the opinion that these cells were only capable of giving rise to certain types of tissue. However, as of late 2000, medical researchers have discovered that small numbers of pluripotent stem cells can be harvested from bone marrow, cord blood, and placentas. It even seems that, under some circumstances, hematopoetic (blood-producing) stem cells can be coaxed to grow into other types of tissue.
Autologous stem cells have been used for many years in patients undergoing high-dose chemotherapy for cancer. Research shows that in certain cases cancer can be more effectively treated, and the risk of cancer recurrence dramatically reduced, by treating it with higher doses of chemotherapy. These drugs cause complete bone marrow failure, so before undergoing treatment, cells are harvested and stored, then reinjected into the patient's blood stream after chemotherapy is concluded. These hematopoetic stem cells then settle in the bone marrow and restore its function.
Umbilical cord blood contains blood stem cells that are even more primitive than the blood stem cells found in bone marrow, but not many people have their stored umbilical cords available. However, cord banks are springing up in every major city, and perhaps someday it will be routine to save the umbilical cord of every baby born. Currently, the service is fairly expensive, with clinics advertising online with fees of approximately $2000 for the first year, and $125 for every year thereafter. However, as the service becomes more popular the price will almost certainly decrease.
Adipose (fat) tissue is a plentiful source of donor tissue which has advantages over many other sources of regenerative-capable cells such as skeletal muscle, bone marrow, embryonic and fetal tissue. It is plentiful, easy to access (unlike painful bone marrow extractions) and consists of a mixed variety of cells useful in tissue regeneration, such as adult stem cells, endothelial progenitor cells which can form blood vessels, and other growth factor producing cells to promote tissue growth and repair.
An animal study of the use of adipose-tissue stem cells was presented at the Transcatheter Cardiovascular Therapeutics 2004 meeting in Washington D.C. by MacroPore Biosurgery, Inc. (Frankfurt: XMP). The research showed that adipose tissue-derived regenerative cells improved heart function following myocardial infarction in a large-animal preclinical safety study performed on swine. The results suggest that the Company's proprietary, patented technology is safe and may be useful in treating heart disease in humans. The adipose tissue-derived regenerative cells were delivered into coronary circulation without prior cell culture.
All 13 swine surviving to the 6-month follow-up period, and 2D echocardiography showed a statistically significant improvement in left ventricular ejection fraction (LVEF) at six-months post-infarction in the treated group compared to a control group.
Aside from experimental work on animals , autologous stem cells are already being employed in veterinary medicine to treat leg injuries in racehorses. The new treatment, developed three years ago by Roger Smith and his colleagues at the UK's Royal Veterinary College in North Mymms, Hertfordshire, requires bone marrow stem cells obtained from the horse's own sternum. The cells are then multiplied in the laboratory and injected into the damaged area, where they regenerate tissue in the clefts typical of these injuries.
Results show that racehorses treated with stem cells recover from tendon injuries faster than those treated conventionally with rest and graduated training. They also have fewer injuries once they return to racing.
Approximately a third of all racehorse injuries are due to tendon damage, and can sometimes leave a horse permanently disabled. Of the 82 racehorses treated in the study, 80 percent showed some improvement.
Even though stem cell treatments have not been thoroughly tested in adults, patients are often happy to be research subjects if they have a disease which conventional medicine has been unable to cure. And with stem cell treatments in the news almost daily, public interest is unlikely to abate. Hopefully, this will help speed up results in this extremely promising field, and give widespread relief for many diseases.
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