All stem cells can replicate over and over, thanks to an enzyme that slows their aging. This enzyme, telomerase, is what makes cancer cells proliferate, too. Stem cells can also make new cells programmed to do specific jobs. Bone marrow stem cells, for example, make red blood cells, which carry oxygen through the body.
In the past decade, researchers have discovered different forms of stem cells, all of which hold promise as tools for developing new treatments for diseases such as diabetes, heart disease, Parkinson's, and Alzheimer's. The FDA just approved the first clinical trial of embryonic stem cells in humans. The trial involves an attempt to repair severed spinal cords in paraplegics.
Here are the three types of stem cells, and their pluses and minuses in medical applications:
Embryonic stem cells are pluripotent. In other words, they can become almost any specialized cell or body tissue. Derived from human embryos left over from in vitro fertilization, they give researchers flexibility to control the growth of cells and tissues needed for treatment. When transplanted, however, donor ESCs could still be rejected by a patient, who in most cases would be a nonrelative. And some people object to using cells from human embryos for research, making embryonic stem cells probably the most controversial topic in biomedicine.
Adult stem cells, like those in bone marrow that form red and white blood cells, are usually limited to forming specialized cells. Adult stem cells in the skin and digestive system are mostly multipotent. These stem cells could be used to regenerate many, but not all, tissues in the body.
Induced pluripotent cells, which closely mimic embryonic stem cells, were first made by scientists from adult skin cells in 2007. These hybrid species make use of a patient's own cells and could skirt the ethical problem of using embryonic stem cells altogether. They also would erase the problem of rejection of donor cells. For now, however, iPSs aren't safe for treatment because the process of making them includes the addition of certain cancer-causing agents.
There is another source of stem cells that gets overlooked on a daily basis. These powerful stem cells are found in healthy developing wisdom teeth. The immature stem cells recovered from extracted wisdom teeth have markers similar to what is found on plurpotential embryonic stem cells. As an oral surgeon and the president of StemSave, Inc, I recommend that individuals are made aware of this valuable source of stem cells. Over 10 million wisdom teeth are removed and discarded as medical waste yearly. If the stem cells within these wisdom teeth were made available to researchers we would have an unlimited resource of stem cells that do not have the moral or ethical issues associated with them when compared to embryonic stem cells. Yes, the stem cells from wisdom teeth are considered adult stem cells and cannot form into all 220 different types of cells that embryonic stem cells can. But for a number of diseases, you need only one type of reparative cell to cure the disease. Another factor that must be considered is the possibility for the rejection of an embryonic stem cell transplant and the need to place the recipient on anti-rejection drugs. This is not the case for adult stem cells recovered from an individual and then reimplanted back into that same individual. I am advocating that we continue to support and expand all types of stem cell research but let’s not overlook a plentiful and accessible source of stem cells, those found within the pulp of developing wisdom teeth. This is coming from a parent of a 12 yr old son with Duchenne Muscular Dystrophy, an incurable degenerative disease. My son is the inspiration behind StemSave, Inc, www.StemSave.com an affordable service that allows an individual to cryopreserve their stem cells from teeth for future regenerative therapies.