Jan 13, 2009
Joan Marie Pellegrini, MD
The use of stem cells in research has created a bit of controversy over the last few years. Most of the controversy arises from either a philosophical difference of opinion or from lack of knowledge about stem cells. This article is going to explain what stem cells are and where they come from. Not all stem cell research is controversial.
There are only two types of stem cells: embryionic and adult. You may also hear about fetal and cord blood stem cells but, for the purposes of definition, these can be grouped with “adult” stem cells.
First, it helps to know what a stem cell is. A stem cell is a cell that is unspecialized and can divide and renew itself. Because it is unspecialized, it can be induced to develop into any type of specialized cell. A pluripotent cell is one that is just a little further along in differentiation but can still be induced to differentiate into only a few different cell types. These terms are often used interchangeably by the media. There is much research in trying to define what makes a cell a “stem” cell and then what makes it develop into a certain type of specialized cell. This process is called differentiation.
Next, it helps to know where we find these stem cells. An embryonic stem cell comes from embryos that have been created for the purpose of treating infertility. Embryos that have not been implanted into a woman’s uterus could instead be used for their stem cells. This becomes an ethical issue if one defines life as beginning once the sperm enters the egg and thus starts the development of an embryo. Fetal stem cells must come from a fetus. The only way to obtain stem cells from a fetus is to remove the fetus from the uterus and this has obvious ethical controversy. Another source of stem cells is umbilical cord blood. There is no controversy in donating cord blood because there is no risk of ending a life or potential life. This is blood that is taken at the time of birth from the umbilical cord before it is cut. This blood can be donated to a cord blood bank or it can be saved in a private bank for future use by the baby or the baby’s family. The final source is adults from whom stem cells can be taken from blood or bone marrow. Most of these cells are actually “pluripotent” cells.
Stem cells have been used for over 40 years to treat disease. A bone marrow transplant is a source of stem cells for the patient receiving the transplant. However, these cells only develop into bone marrow and blood cells. Other sources of stem cells or pluripotent cells are skin, heart, and the gastrointestinal system which use them for repair.
Scientists think that almost any disease may eventually be able to be treated with cell therapy. However, most current research is focused on identifying sources of stem cells, growing stem cells, and controlling how stem cells differentiate. This is truly a growing and fascinating field with exciting potential. There are many ways this research can be done without inciting ethical controversy.
If you would like a more in depth review of this field, I have found the following web site to be very easy to understand. It also offers links to other sites with more information: http://stemcells.nih