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About Stem Cell ResearchSeparating fact from fears and reality from hearsay — and understanding what stem cell research is and is not — begins with basics. Michigan Citizens for Stem Cell Research & Cures is helping our state's citizens to develop a better understanding of this complex science, the biomedical potential and the current politics affecting stem cell research in Michigan. There are two basic categories of stem cells: adult/tissue stem cells that exist in many different fetal and adult tissues, and embryonic stem cells that only exist at the earliest stage of embryonic development. Embryonic stem cells can make any cell type in the body, whereas adult/tissue stem cells are partially specialized and can generally only make cells from their tissue of origin. There are many different types of adult/tissue stem cells, including blood-forming stem cells found in bone marrow, nervous system stem cells found in the brain and skin stem cells found in the skin. Embryonic stem cells are primitive cells that can be generated in a laboratory dish. Four to five days after an egg is fertilized by sperm in a dish in a fertility clinic, the dividing mass of cells is called a blastocyst. For a variety of reasons, not all blastocysts can be used for fertility treatment and thousands of these embryos are routinely discarded by fertility clinics. After parents have made the decision to discard these excess embryos, in most states they have the option of donating them for medical research. To make an embryonic stem cell line from embryos slated to be discarded, the inner cell mass or ICM can be removed from the blastocyst and embryonic stem cells can be grown from the ICM in a separate dish in a lab. Under the right conditions, these embryonic stem cells retain the ability to divide and make copies of themselves apparently indefinitely. This is called an embryonic stem cell line. Adult/tissue stem cells, by comparison, are present in adults, children, infants, umbilical cords and developing fetuses. They are more limited and specialized than embryonic stem cells. They can make just one or two specific kinds of tissue, such as blood and immune system cells. Additionally, their capacity to replace themselves is more limited than with embryonic stem cells, so there are often fewer cells to work with. Although they are less versatile than embryonic stem cells, they may also be used to treat patients. For example, when cancer patients are given a bone marrow transplant, they receive blood-forming stem cells that rebuild their blood and immune systems. While blood-forming stem cells can make all types of blood and immune system cells, they cannot make cells from other tissue like the brain, skin or other tissues. We still have a great deal to learn about both adult/tissue and embryonic stem cells and their potential for treating disease. Both have distinct advantages and disadvantages associated with them and each offer important insights. For more details on the characteristics of adult/tissue and embryonic stem cells, click here to review information from the University of Michigan Life Sciences Institute . You can also click here for the International Society for Stem Cell Research.
Useful LinksRegenerative Medicine 2006 (Department of Health and Human Services) International Society for Stem Cell Research Michigan Citizens for Stem Cell Research & Cures brochure
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Copyright © 2006 Michigan Citizens For Stem Cell Research & Cures