Feb 14, 2002
By Jacqueline Stenson
Though often referred to as "therapeutic cloning," the process that scientists use to create stem cells for medical research and treatment is not intended to create carbon copies of people and therefore should not be given the controversial "cloning" label, researchers say.
Precise terminology is important because US lawmakers are considering a ban on cloning that would outlaw both reproductive and therapeutic cloning, the researchers write in an editorial in the Feb. 15th issue of the journal Science. Last year the House of Representatives passed a ban on both types of cloning, and the Senate is considering legislation on the issue.
While most scientists agree that reproductive cloning--the type that resulted in Dolly the sheep and other cloned mammals--is dangerous and should not be attempted in people, many believe that so-called therapeutic cloning offers great medical potential.
Doctors are experimenting with using stem cells, the master cells that are the building blocks for all types of human tissue, to replace tissue that has been damaged or diseased by stroke, Parkinson's disease, diabetes, heart attack and many other conditions. The hope with this approach for creating stem cells is that the patient's body will not reject the transplanted tissue because it is derived from the patient's own DNA.
"Banning cloning in general would have an enormous impact," Dr. Bert Vogelstein, a researcher at Johns Hopkins University in Baltimore, Maryland, told Reuters Health. Vogelstein does not perform stem cell research, but he was the chairman of a National Academy of Sciences committee that issued a report last fall in support of public funding for the research because of its medical promise. He co-authored the editorial in Science, along with two officials from the NAS, an independent research arm of the government.
In the procedure commonly referred to as therapeutic cloning, scientists extract the nucleus of a patient's cell and transplant it into an egg that has been stripped of its own nucleus. The egg is coaxed to grow into an embryo, which contains stem cells.
While this embryo theoretically could develop into a cloned human if implanted into a woman's uterus, scientists harvest the stem cells in the lab within days. The procedure is controversial because some people view it as creating life only to destroy it.
But the intent is never to clone a person and the process should not be termed cloning--therapeutic or otherwise, the authors said. A more accurate term, they propose, is "nuclear transplantation." They said this term makes a clear distinction between the process for producing stem cells and that which is intended to produce clones, which should be referred to as "human reproductive cloning."
"Cloning means something very specific," Vogelstein said in an interview. "If I ask a man on the street, he says a clone is an exact copy of a human being. Cloning means you're trying to create a copy of an individual organism. Nuclear transplantation is not cloning."
Researchers are also experimenting with stem cells harvested from adult tissue, though these are generally considered less versatile than the embryonic stem cells, which appear capable of developing into virtually any type of cell.
SOURCE: Science 2002;295.
Copyright © 2002 Reuters Limited