The Dangers of Delay : Restrictions on stem-cell research in the United States will exact costs on American doctors as well as potential patients.

In August 2001, when President George W. Bush announced that federal funds could be used to support research on human embryonic stem cells, he mandated that only those cell lines that existed at the time would qualify for such support. More than a year later it's becoming increasingly clear that these existing cell lines are inadequate. Unless more are created, the research slowdown may exact a staggering cost in terms of human suffering.

Since this announcement, the U.S. National Institutes of Health has tried to stimulate research on the existing cell lines with new funding and efforts to streamline the initially cumbersome process of obtaining approved cells. However, whether there are 60 cell lines, as originally stated, or nine, as now appear to be available to NIH-funded investigators, the number is not adequate. Given the genetic diversity within the population, scientists need access to new cell lines if they are to come up with the most effective cell therapies.

The issue is partly one of safety. In conducting research with human participants, we must minimize risks. The most effective cell line might not be the safest. When developing a new medicine, a large number of molecules must be screened to find a balance between effectiveness and safety. The same is true with cells. In the context of cell therapy, it will be important to minimize unwanted immune reactions and inflammation. This requires selection from a large number of cell lines to obtain the best match.

It's clear from experiments with animals that stem-cell therapies can reduce human suffering. Parkinsonian mice have been cured with embryonic stem cells that were programmed to become dopamine-secreting, replacement nerve cells. Soon, cells induced to make insulin in tissue cultures will be used in attempts to treat diabetic mice. Similar successes have been achieved in animal models of spinal-cord injury, heart failure and other degenerative disorders. We are at a frontier in medicine where tissues will be restored in ways that were not imaginable just a few years ago. The ethical issues raised by human-embryo research are profound. The human costs of restricting this research must be taken into ...