What are stem cells?
They are the precursor cells from which all the tissues in the body develop. They can continue replicating indefinitely and have the potential to develop into any specialized cell type, such as blood cells or neurons.
Why are they important?
In addition to teaching scientists about how cells grow and develop, most researchers feel that stem cells offer great medical promise for future medical treatments.
Stem cells could provide replacement cells to treat diseases such as heart disease, Alzheimer’s, diabetes, and cancer. Ultimately, they might allow the growth of replacement organs.
What types are there?
Embryonic (or pluripotent) stem cells are formed when a human embryo reaches the blastocyst phase a few days after fertilization. They are the most versatile and can develop into any type of tissue.
Adult (or multipotent) stem cells are formed by the body to replace worn-out cells in many organs and tissues. These cells can only develop into a few predetermined tissue types.
Adult stem cells are much more difficult to keep alive and growing in the laboratory, yet there have been several recent successes. Scientists differ in opinion on the relative usefulness of adult and embryonic stem cells.
Stem cells collected from animals are also commonly used in research, but the medical use of such cells is limited by fear of zoonotic diseases and immune rejection.
Why all the debate?
Many people are opposed to the destruction of a human embryo for any purpose, feeling that it violates the sanctity of human life. However, many others support the research, arguing that the potential medical benefits will help cure many diseases and that the discarded embryos being used would never have had the chance to form a living human.