Scientists at Harvard University in the United States say they may have made a breakthrough toward developing embryonic-like stem cells that could be used for organ transplants and other medical treatments.

Harvard scientists have developed a procedure to combine ordinary skin cells with embryonic stem cells to create stem-cell like properties - a procedure that might eliminate the need to create and destroy human embryos.

Stem cells are immature cells that can become any kind of tissue in a developing fetus. For years, the scientific community has seen stem cells as a way to create genetically tailored organs for transplants and to treat cancer and other diseases. But the best source of the cells is embryos.

This new process involves fusing an embryonic cell taken from a lab-grown stem cell line with a person's skin cell to create a new hybrid cell; one with the genetic material, called DNA, of the person who donated the skin cell but also the DNA and properties of the lab-grown embryonic stem cell.

The Harvard researchers say they were able to show that the fused hybrid cell was in their words, "reprogrammed to its embryonic state," showing characteristics of embryonic stem cells.

Dr. John Gearhart

Dr. John Gearhart, a stem cell researcher at the Johns Hopkins Medical School in Baltimore, Maryland, says these are NOT embryonic cells. "We have to take this study with circumvention which says it's a beginning," he says. "These cells still have two complete sets of chromosomes and this is the issue at the moment: How do we get rid of one set of chromosomes that is responsible for reprogramming the other set?"

Some method will have to be developed to remove the embryonic DNA so that the remaining genes will match the adult donor for whom the stem cell therapy is being tailored, to prevent his immune system from rejecting it. Researchers in Illinois and Australia are working on removing the extra DNA from the hybrid cell.

Dr. Gearhart says this procedure is a long way from becoming a practical treatment for anything. "We really have to demonstrate, as I think these researchers have pointed out, that we have a long road ahead of us to demonstrate that the types of cells that they are generating will ultimately be safe for therapeutic use."

The new technique could eventually permit scientists to create new stem cell lines without using human eggs or destroying human embryos as a source, a controversial issue in the United States and elsewhere.

U.S. law bans the use of government money for this kind of research, although legislation is pending in Congress to overturn this ban. President George Bush threatens to veto any law to overturn the ban, but it is gaining support among many of his supporters because they consider the research a way toward promising new treatments.

Dr. Gearhart says the possibility exists that the fusing technique could circumvent ethical concerns and become an important source for creating stem cells.