Re: Why do adult stem cell show more promise than embryos

For our less savvy readers out there, let’s start out with some basic information on stem cells. Most cells in the body are considered “differentiated” cells. That is to say that they have a very specific function within the body and are capable of carrying out only a very narrow range of activities. Stem cells are cells that for some reason have no differentiated yet into their final cell type. Thus, it is speculated, that with the proper treatment stem cells can be coaxed into becoming any number of kinds of cells. Scientists have long known that the first few cells that arise in a human embryo (the result of the fertilization of an egg by a sperm) are stem cells. Because no real tissues exist in the early stages of embryogenesis, the cells must have the potential to give rise to all of the cells that will eventually make up that person. A little more surprising, though, was the discovery in the 1960’s that some cells in mature adult tissue also have the ability to differentiate into mature cells. Tissues ranging from bone marrow to neuronal tissue contain these cells, which are called “adult” or “somatic” stem cells. Adult stem cells are a little different from embryonic stem cells, though. They tend to be less undifferentiated than embryonic stem cells – that is to say, adult stem cells found in bone marrow can only because blood cells, white blood cells, other bone marrow cells, bone cells, or connective tissue cells. Adult stem cells from the nervous system can only become cells found in the nervous system already, and so on. Embryonic stem cells should theoretically be able to become any kind of cell in the human body. Since the adult stem cells are already found in the places where they are of the most use, some people believe that they will be easier to use to treat disease – though nobody has been able to show this so far. Similarly, because of certain laws currently in place in the United States, very limited research has been carried out on embryonic stem cells, and so no useful therapies have emerged from them either. It is interesting that you bring up the problem of tissue rejection. Indeed, that has been one of the tricky parts of using embryonic stem cells. Ostensibly, a stem cell from an embryo that wasn’t identical to the person receiving the stem cell therapy would suffer from rejection unless the stem cell was a “match” like in traditional organ therapies. Scientists are working on ways of getting around this by creating embryos by removing the nucleus from the cell of a person and putting it into an egg, creating a sort of hybrid embryo. This is a very touchy subject, though, because this could very quickly lead to a clone. Adult stem cells taken from a person and used to treat that persons disease would probably not trigger this immune response. However, let’s look at the case of a person with juvenile onset diabetes. The predominant theory suggests that a person’s immune system attacks and destroys beta cells in a diabetic pancreas…these are the cells that create insulin, a hormone that lowers blood sugar. If stem cells were taken from a diabetic and used to grow new beta cells, what would stop the immune system from tearing those up as well? Nobody has the answer to this question yet – so stem cells probably should not be viewed as a magic bullet. They do, however, possess interesting characteristics that may someday lead to cures for many of our most serious diseases. In conclusion, I would like to say that adult stem cells do not necessarily show more promise than embryonic stem cells. Each kind of stem cell has its own inherent benefits and weaknesses, and only time and lots of research will show which (if either) is more useful. If you are interested in further information, The National Institutes of Health and Wikipedia have a lot of information available online about both embryonic and adult stem cells, and their possible uses and ethical debated about their use. I highly suggest them both. “Stem Cell Information.” National Institutes of Health. 6 October 2006. 1 November 2006. http://stemcells.nih.gov/index.a sp “Stem Cells.” Wikipedia. 2 November 2006. 2 November 2006. http://en.wikipedia.org/wiki /Stem_cell “Embryonic Stem Cells.” Wikipedia. 1 November 2006. 2 November 2006. http://en.wikipedi a.org/wiki/Embryonic_stem_cell “Adult Stem Cells.” Wikipedia. 25 October 2006. 2 November 2006. http://en.wikipedia.or g/wiki/Adult_stem_cell