Final guidelines were issued Monday by the U. S. government regarding stem cell research, which will allow many older stem cell lines to be eligible for federally financed research.

Researchers will have to demonstrate that embryonic stem cells used in research were obtained from fertility clinic embryos that otherwise would have been discarded and the stem cells must come with the informed consent of the parents or mother. However in the case of stem cells that were developed earlier such documentation will not be required.

In a news conference Dr. Raynard S. Kington, acting director of the National Institutes of Health, said that his agency would insist that the new rules would be adhered to by any scientists creating stem cell lines after Tuesday for their work to be eligible.

Dr. Kington added that scientists using stem cell lines created before Tuesday can seek review by a group of the Advisory Committee to the Director. They will be approved if the lines were created under conditions that met the spirit but not the letter of the new rules.

"Many of the lines already in existence may have met very rigorous standards of informed consent but may have been implemented in ways not consistent with the present guidelines," Dr. Kington said. "It's unreasonable to retroactively apply procedures intended for future use."

The new guidelines take effect Tuesday still ban federal financing for research on stem cell lines derived from embryos created solely for research.

In March, an executive order that he said would allow federal taxpayer dollars to fund significantly broader research on embryonic stem cells was signed by President Barack Obama who said, "Medical miracles do not happen simply by accident."

This overturned a Bush administration policy which limited government funding of human embryonic stem cell research to cell lines already in existence as of August 2001.

Paul R. Sanberg, director of the Center of Excellence for Aging and Brain Repair at the University of South Florida College of Medicine in Tampa said, "The more information we have about these cells that are used for research or potential treatment, the better off we'll be. It's important that there be documentation on tissue, on embryonic cells, that informed consent was received."

Dr. George Q. Daley, director of the stem cell transplantation program at Children's Hospital Boston said, "I'm very pleased they have taken feedback of an overwhelming majority of the scientific community and responded with a science-friendly proposal."

Regarding the creation of a registry of stem cell lines that meet the agency's approval Dr. Daley said, "Every institution shouldn't have to rediscover which cell lines are eligible for N. I. H. funding, so having a registry is very practical."

A controversial area, embryonic stem cells are the most basic human cells, believed to be capable of growing into any type of cell in the body. As a repair system these stem cells can divide to replenish other cells and scientists are hopeful that in the future stem cells could be used to treat a variety of diseases and conditions such as Parkinson's disease, diabetes, heart disease and spinal cord injuries.

Polls conducted in this regard have found majority of Americans favor embryonic stem cell research

though that support has declined somewhat in recent years.

Those who oppose stem cell research do so as they feel the research requires the destruction of potential life as the cells must be extracted from human embryos.

The new guidelines met with approval from different medical societies. In a statement the American Society for Reproductive Medicine (ASRM) spokesman Sean Tipton said, "The guidelines released today reflect the tremendous importance of embryonic stem cell research, while assuring that federal funds will only be available for use on stem cell lines derived under appropriate ethical supervision. The scientific community is pleased that the policymaking is complete and is ready to get to work at learning how to tap the power of embryonic stem cells to relieve human suffering."