WESTPORT, Nov 30 (Reuters Health) - Transplantation of modified stem cells improves the locomotion of rats with spinal injury, according to study findings appearing in the December issue of Nature Medicine.

A team of researchers at Washington University in St. Louis took embryonic stem cells and treated them with retinoic acid to transform them into neural differentiated cells. Then, 9 days after spinal injury, the researchers injected the cells into the rats at the injury site.

Two weeks later, the researchers, who had marked the transplanted cells genetically, detected the cells throughout the injury site. Individual cells were present as far as 8 millimeters away.

The transplantation had a beneficial effect on locomotion, according to the report. Two weeks after treatment, there was a statistically significant improvement in the treatment group, compared with rats that received a sham operation.

"[R]ats transplanted with (embryonic stem) cells demonstrated partial weight-supported ambulation," the authors write.

"Their walking certainly wasn't normal," the study's lead author, Dr. John W. McDonald, of Washington University School of Medicine in St. Louis, said in a news release. "But this functional recovery was especially encouraging because the precursor cells were transplanted 9 days after the spinal cord injury--a time period that has not been explored before."

Furthermore, since only a small number of the transplanted cells survived, improving cell survival might bring more benefits, according to Dr. McDonald.

Stem cell transplantation remains controversial, and scientists, physicians, bioethicists and politicians continue to weigh its moral impact on medical research, according to a separate Nature Medicine article. The National Institutes of Health (NIH) and the National Bioethics Advisory Committee are both involved in addressing issues of stem cell research funding and guidelines, and each is bound by the opinions of a review panel established by the Department of Health and Human Services.

However, according to the article, the debate can benefit from a new independent oversight panel comprised of scientists, medical, legal and ethical experts, as well as theologians.

"If the federal government wants to actually influence how research is done on human embryos and fetal tissue, it must set forth clear and unequivocal rules that cover not just the research it funds, but all research, including privately financed research," Dr. George J. Annas, a medical ethicist at Boston University School of Pubic Health, in Massachusetts, and others from elsewhere write in the December issue of Nature Medicine.

"Failure to explicitly address the ethics of using spare embryos as a source of stem cells not only invites continued political and ethical controversy and public disquiet but cedes the moral case to opponents of their use," they write.

"Although the destruction of a human embryo is lamentable, there is a considerable moral difference between creating and destroying embryos solely to obtain stem cells and destroying unwanted human embryos that will never be used for reproductive purposes, to achieve benefit for those with serious diseases and disorders," the authors write.

"A federal oversight panel, independent of the NIH and HHS, should be [authorized by Congress] with authority to promulgate all regulations for research involving the use of human embryos...stem cells and other cell lines derived from human embryos or aborted fetuses."

"The promise of stem cell research for millions of patients may afford an outcome in which the ethical debate can be resolved democratically in Congress," Dr. Annas and colleagues conclude. "This opportunity to move from ethical gridlock to responsible ethical oversight of such research should not be missed."

Nat Med 1999;5:1339-1341,1410-1412.