In biological terms, embryonic stem cells have a virtually unlimited future. Given the right signals, these stem cells can be coaxed to grow into any specialized cells in the human body, from brain cells to heart muscle.

The politics of abortion, unfortunately, has cast considerable doubt on their future as miracle cures. Federally funded research on embryonic stem cells has been put on hold while the National Institutes of Health (NIH) reviews the legal and ethical concerns raised by a vocal minority of anti-abortion advocates. Meanwhile, scientific and patient groups and millions of Americans are anxiously awaiting the decision of the Bush Administration, expected sometime this summer. The Alliance for Aging Research believes it would be indefensible not to capitalize on these tantalizing potential new medical treatments to improve the lives of millions of people suffering from chronic diseases.

At the heart of the debate are the embryonic stem cells themselves, which are extracted from embryos at in vitro fertilization labs that are produced in quantity during fertility treatments, but end up not being used and often are discarded. At this stage of development, they represent a handful of undifferentiated cells that form the potential of life, but only if they are implanted in a woman's womb, and tens of thousands never will be.

Opponents of embryonic stem cell research contend that destruction of these embryos amounts to abortion. They fiercely oppose government involvement in any such research, no matter how the stem cells are obtained or how beneficial the results might be.

Dr. James Thomson, a developmental biologist at the University of Wisconsin-Madison who first cultured human embryonic stem cells in 1998, also points out that embryonic stem cells can divide indefinitely, providing a seemingly limitless source of stem cells. In theory, then, a small number of fertilized eggs could produce all the stem cells researchers will ever need.

Abortion opponents say they have no objection to using adult stem cells, found in some body tissues, such as the brain, skin or bone marrow. And, researchers agree that adult stem cells may hold promise for certain therapies. Scientists are quick to point out, however, that adult stem cells are not as versatile as embryonic stem cells in their ability to become various tissue types, and do not; therefore, offer the same lifesaving qualities. "Adult stem cells will certainly have a role to play," Thomson told the Alliance. "But to cut off one of these avenues certainly would be unfortunate."

Researchers like Dr. Thomson believe embryonic stem cells may hold the key to developing radically new therapies for degenerative diseases such as Alzheimer's or Parkinson's and life threatening illnesses like diabetes, cancer and cardiovascular disease. They also offer a rich source of healthy tissue to repair diseased organs. Damaged hearts, for instance, might someday be repaired not with surgery or heart transplants, but simply by injecting embryonic stem cells into the heart.

Shutting off federal funds for university research still would allow the research to go on in private labs and biotechnology companies. But the pace of medical discoveries almost certainly would slow to a crawl if it were limited to the private sector. "The best minds in this research are still in academia, not industry," Dr. Thomson told the Alliance. "To exclude the best minds in the whole field would set back the effort tremendously."

Privately funded research also would eliminate the oversight and public scrutiny that would come with federal funding, thereby increasing the potential for abuse. The Alliance agrees with Thomson's assessment of the benefits to be derived from government involvement. "There could be a lot of things done privately that would be widely repugnant," Thomson warned. "Society benefits from open research, so people can see what's happening."

Banning federal funding of this research also risks losing our national dominance in biomedical research. Momentum would shift overseas to countries like Australia, Britain and Israel, whose governments have approved less stringent restrictions on embryonic stem cell research.

An unprecedented 80 Nobel laureates have urged President Bush not to halt federal funding of embryonic stem cell research. They include such notables as James Watson who co-discovered the DNA double helix, and economist Milton Friedman. In their letter to Mr. Bush, the laureates noted that the embryos to be used in the research were destined for destruction anyway. They wrote, "Under these circumstances, it would be tragic to waste this opportunity to pursue the work that could potentially alleviate human suffering."

Health and Human Services Secretary Tommy Thompson, whose department oversees NIH, is an abortion opponent and also an enthusiastic supporter of embryonic stem cell research. For that reason, Secretary Thompson seems ideally suited to the task of convincing his boss that this research must continue.