Quezi

Use of embryonic stem cells for research has become a hot topic in U.S. politics. Internets Dairy photo. CC-BY

Stem cells have been called the master cells of the human body. Unlike other types of cells, stem cells have the capability, as they reproduce, of becoming other types of cells. So, for example, a muscle cell will always be a muscle cell. But some types of stem cells, though a series of divisions, might become a muscle cells or nerve cells or something else.

Not all stem cells are created equal, however. Stem cells found in adults have limited capabilities to become other types of cells. But the stem cells of embryos only a few days old are remarkable: They eventually become any of the 300 or so types of cells found in the human body. Skin, brain tissue, muscles, livers, eyes — they all originate from the same stem cells that can be found in embryos a few days old.

What distinguishes stem cells from other cells is that they are unspecialized, unable to fulfill any functions by themselves (until they turn into other kinds of cells). In adults, stem cells typically turn into the types of cells found in the environment where they are located. For example, stem cells found in bone marrow reproduce themselves into blood cells. Embryonic stem cells inherently have more potential (in scientific lingo, they have plasticity).

Scientists have long recognized the potential that such cells could have. In theory, at least, it would be possible to take stem cells and make them into tissue that could be transplanted into people who have serious illness or injuries. Or it might be possible to develop synthetic organs that would manufacture hormones and other body chemicals that could be used by people who need them.

The problem is that the use of embryonic stem cells for research raises profound ethical questions. Many people — often, but not always, out of religious conviction — see no moral difference between destroying an embryo to use its stem cells for research and killing an adult for research. As a result, in many countries the use of embryonic stem cells has been restricted. In the United States, for example, the George W. Bush administration allowed the use of embryonic stem cells for research, but only if those stem cells came from embryos that already existed and would otherwise be discarded. Other countries place no restrictions on the use of embryonic stem cells.

The debate over the ethics of embryonic stem cell research shows no signs of abating. However, it is possible that scientists may find a way to give adult stem cells more plasticity — in other words, giving adult stem cells the same capability of turning into other types of cells as embryonic stem cells have. If that were to happen, stem cell research could go on without the destruction of human embryos. The adult stem cells might be obtained, for example, from bone marrow that would eventually replace itself.