IN APPROVING federal funding for embryonic stem cell research, President Bush cleverly walked a tight line of politics and principles on a complex biomedical and moral issue.
The decision allows funding for work on existing stem cell lines to search for cures to a wide range of diseases and physical defects. The president will create a council to develop federal guidelines and monitor this promising research, which has been privately funded, often secret and without regulation.
But the limits imposed by a cautious Mr. Bush, excluding any new stem cell lines developed from embryos, will slow the pace of scientific discovery.
He has greatly overstated the number of existing cell colonies available, even in private labs around the world, and their genetic variability. It's unclear if stem cells derived from aborted fetuses will be eligible for funding. Cells from cloned human embryos are excluded by the president, since that would involve destroying the embryo to extract the cells.
Still, there is relief that Mr. Bush will allow funding for some embryonic stem cell research. President Clinton tried last year to do so in the face of a congressional ban, but his guidelines did not go into effect.
Stem cells are basically blank master cells taken from a 5-day-old embryo that can be turned into virtually any type of body tissue. Those specialized cells, researchers hope, could then be transplanted to patients to correct disorders such as diabetes, Alzheimer's, heart disease and spinal cord paralysis.
But that theory is still very much a promise in terms of human application. Stem cells were discovered by U.S. researchers barely three years ago. They have not helped any human yet.
Scientists are uncertain how many colonies of stem cells would be needed for a full range of therapies and research. Cell colonies continue to regenerate but some existing lines may be fragile and of uncertain origin. Having enough of the curative cell lines to match human variations is a major concern.
Stem cells from adult tissue, umbilical cords and placentas will receive additional funding. While they avoid the moral dilemma of embryo destruction, they are less versatile and valuable for research.
As private research on stem cell cloning and development of new embryonic lines continue, the issue is far from resolved. Congress may expand funding for wider stem cell research, or even further limit it. President Bush's funding decision announced Thursday is a timid step down a long path toward human discovery.
