Embryonic stem cell research is a branch of science that looks for ways to use stem cells for regenerative or reparative medicine. Scientists study how the cells can best be used to treat burns and traumatic injuries to the brain and spinal cord, as well as degenerative diseases like arthritis, Alzheimer’s, Parkinson’s, chronic heart disease, and diabetes. Despite the potential to treat and cure injury and illness, ethical concerns have slowed the progress of embryonic stem cell research.
The embryonic stem cells harvested from human fetuses are called pluripotent stem cells, meaning they have the ability to develop into all other types of cells. Pluripotent stem cells are usually harvested from the inner cells of the blastocyst, which is a week-old embryo that hasn’t yet implanted into the placenta. Theoretically, these cells can regenerate indefinitely in a living organism. Each time they divide, they create two daughter cells which are either more stem cells or other specified types of cells like blood, liver, or brain.
Embryonic stem cell research looks for ways to induce pluripotent embryonic stem cells to produce specific types of cells, which are grown in a laboratory. The cells can then be used to repair damaged or degenerating organs, although safe and effective ways to transplant pluripotent stem cells are still being studied. Testing on mice shows the potential to regenerate organs and testing on chimps shows that stem cells can repair damaged neural tissue.
Theoretically, neural stem cells injected into an injured adult spine will repair damage by growing new neurons. Treatments like this are in the earliest phases of clinical trials on humans. One problem scientists face is insuring stem cells don’t grow into cancer cells, which is why the cells cannot simply be injected into the body. Instead, researchers must create cells with very specific purposes and test them to make sure they behave as expected.
The ethical debate around embryonic stem cell research is generally focused on the source of the stem cells rather than the research itself. Stem cell research on cells from human fetuses is highly controversial because some people believe it is tantamount to abortion or harvesting human parts for medical research. Most stem cells used in research, however, are from fetuses that were aborted for reasons other than research or that were created in vitro in fertility clinics, and would otherwise have been thrown away. A stem cell implanted into a woman’s uterus will not grow into a human baby.