What Are Stem Cells?
Stem cells are cells that are capable of becoming new stem cells (self-renewal) or specialized cells that perform specific functions (differentiation).
There are 2 types of stem cells:
- Embryonic stem cells
- The come from an in vitro fertilization procedure from unused embryos that have been donated to science
- These types of cells can turn into more than one type of cell (they are considered “pluripotent”)
- When stem cells are obtained from living human embryos, the harvesting of these cells necessitates destruction of the embryos, which is controversial in the U.S.
- Adult stem cells (“non-embryonic” stem cells): 2 types
- One type comes from fully developed tissues such as the brain, skin, and bone marrow
- These types of cells can be found in in adults, children, infants, placentas, umbilical cords, and cadavers
- There are small numbers of stem cells in these tissues which tend to generate only certain types of cells (i.e., a stem cell that comes from the liver can only produce more liver cells)
Another type is induced pluripotent stem cells, which are adult stem cells that are changed in a lab to be closer to embryonic stem cells, though unlike embryonic stem cells they cannot develop into every kind of cell and tissue
What Are Stem Cells Used For?
Currently, the only stem cells now used to treat disease are from blood cell-forming adult stem cells found in bone marrow.
These types of cells are used in procedures such as bone marrow transplants, as adjunct therapy for the treatment of leukemia, or to treat people with conditions such as Fanconi anemia.
Hematopoietic stem cells (stem cells that form blood and immune cells) are used for burn therapy, bone grafting, and corneal transplant tissues.
Scientists believe stem cells can be used for many different medical applications in the future, for example, by creating new heart tissue to transplant into a damaged heart to treat heart disease.
What Is Stem Cell Research?
Stem cells are being investigated in several possible roles in medicine:
- As therapy either to replace cell lines that have been lost or destroyed, or to modify the behavior of other cells
- As targets of drug therapy
- To generate specialized cells that perform specific functions (differentiated tissue) for in vitro study of disease models for drug development
Is Stem Cell Research Illegal in The United States?
Stem cell research is legal in the United States, however, there are restrictions on its funding and use.
State laws regarding research on stem cells vary widely, particularly in regard to use of embryonic stem cells. On one end of the spectrum, eight states (California, Connecticut, Illinois, Iowa, Maryland, Massachusetts, New Jersey and New York) encourage embryonic stem cell research, while on the other end of the spectrum, South Dakota strictly forbids research on embryos.
A number of states restrict research on aborted fetuses or embryos, but in some cases, research may be permitted with consent of the patient.
