Embryonic stem cells are taken from embryos in the blastocyst stage, formed in the process of in vitro fertilization and donated for research. There are different kinds of embryonic stem cells, with different characteristics. The cells’ uniqueness and usefulness lie in their being totipotent or pluripotent (having the unique capacity to differentiate into any cell type in the organism), in their capacity for continuous self-renewal, and in the relative ease with which they can be grown in a culture.
Stem cells are used to build models for understanding diseases, developing new pharmaceuticals and therapies for a wide range of ailments (genetic, infectious, and traumatic), and growing healthy tissues to replace damaged or diseased tissues. They have shown potential for treating conditions such as:
- Blood and immune system diseases and conditions, or rehabilitation of the circulatory system following treatment of certain cancers (blood stem cell transplantation).
- Serious burns covering a large portion of the body (by growing implants from skin stem cells).
- Neural paralysis (by injecting nerve cells into the brain following a stroke).
- In the future: other neurological diseases, such as Parkinson’s, Alzheimer’s, and ALS, as well as diabetes, liver, and heart disease.
Selected ethical issues:
- Exploitation and destruction of embryos – the source for embryonic stem cells.
- Balancing the medical benefits inherent in the development of treatments based on embryonic stem cells (and the moral imperative to prevent or ease suffering) against the value of the embryo’s life.
- Use of existing surplus embryos to produce cells as against the use of designated embryos to produce the cells.