Alternatives to Embryo Research

Even as researchers and politicians press for stem cell research requiring the destruction of human embryos, new scientific advances suggest that such abuses may be irrelevant to medical progress. In January, researchers made three announcements about progress toward regenerating and replacing diseased or damaged human tissue that does not require harvesting cells from unborn children:

"Immortality enzyme"

Ordinarily, as body cells age they stop growing, at least in part because the ends of chromosomes develop caps (called " telomeres") that prevent further dividing. But researchers have isolated an enzyme, telomerase, that dissolves these caps and may keep tissues growing almost indefinitely - - earning it the nickname "the immortality enzyme."

Fast-growing cancer cells contain a great deal of telomerase. But in the January 1999 issue of Nature Genetics, researchers say they have used the enzyme in a controlled way to "immortalize" useful tissue, without producing cancerous growth or other side-effects. One of the most useful traits of embryonic cells - - their ability to divide and grow quickly - - may be stimulated in patients' own cells to regrow tissues and organs.

Growth factors

Already in use as an experimental treatment is a kind of gene therapy that can help patients grow new tissues. A gene that controls production of growth factors can be injected directly into a patient's own cells to grow new blood vessels. In early trials this treatment saved patients' legs that would otherwise have been amputated (Circulation, March 31, 1997).

Now, according to a report at the annual convention of the American Heart Association, it has grown new blood vessels in the heart. In January it was reported that the technique has helped 19 of 20 patients with blocked cardiac blood vessels (Washington Post, January 27, 1999). Supporters of embryo research have declared that embryonic tissue may someday be used to grow new heart tissue, apparently unaware that this achievement is already here - - without any use of embryos.

Adult stem cells

The most startling advance of all is announced in the January 22 issue of Science. Researchers have succeeded in making an adult mouse's nerve stem cells cross over to produce blood cells, in a case where the latter were more needed by the body. Until now, it was thought that adult stem cells were restricted to producing a narrow range of cells. Researchers believed, falsely, that only embryonic cells were versatile enough to form all the various kinds of cells in the body.

If adult stem cells can become just as flexible, a patient with Parkinson's disease, for example, might grow new brain tissue using extra blood stem cells from his or her own bone marrow. At a January 26 Senate hearing, National Institutes of Health Director Harold Varmus observed that the experiment so far has only succeeded in mice - - but that was also true of the culturing of embryonic stem cells a few years ago. Moreover, Varmus's own January 26 testimony proposes using embryonic cells to treat diabetes based solely on success in mice!

Finally, if a patient's own stem cells can be reprogrammed as needed, a major obstacle to use of embryonic tissue - - the danger that the body may reject foreign tissue - - would pose no problem.