Medicine: Help From The Unborn Fetal-cell

In a widely heralded mercy mission after the nuclear-plant disaster in Chernobyl last spring, Dr. Robert Gale of UCLA and three colleagues flew to the Soviet Union and worked tirelessly to save the radiation victims. Virtually ignored in the reports from the scene was the fact that Soviet physicians and Gale tried a controversial new technique on six of the most severely irradiated Chernobyl workers: fetal-cell surgery. In a desperate attempt to reconstitute the blood-forming tissues of these victims, the doctors transplanted liver cells from human fetuses aborted in the first months of pregnancy.

Those efforts were in vain; all six patients died within a week of the accident. Nonetheless, that Gale used the technique at all reflected the growing confidence of many doctors that fetal-cell surgery could soon become an important medical tool. In the People's Republic of China, physicians have used fetal-cell implants to treat diabetics. In Sweden, researchers have performed fetal-brain-cell transplants to rid rats of Parkinson's disease, a progressive and hitherto incurable neural disorder. In the U.S. and elsewhere, fetal-cell experiments with animals have shown promise of treatments for a host of other human disorders, ranging from blood diseases like thalassemia to paralysis caused by spinal-cord damage. Says Neurosurgeon Barth Green of the University of Miami: "This field isn't growing, it's exploding."

But why implant fetal cells into adults? Fetal cells, Gale explains, are "immunologically naive": during the early stages of pregnancy, they have not yet developed all the antigens, or distinctive surface proteins, that allow the recipient's immune system to identify and reject them. Another advantage of fetal cells is that they are generally not mature enough to cause graft-vs.-host disease, which can occur when the tissues of a transplant recipient are attacked by implanted adult cells. Also, fetal nerve cells, unlike adult cells, can regenerate and thus have the potential to repair a damaged brain or spinal cord. "These properties," says Green, "make fetal cells a very exciting glue to tie together injured or diseased areas of the body."

Of all the uses of fetal-cell surgery, the most successful to date has been the treatment of Type 1 (insulin-dependent) diabetes. This disease, which afflicts about a million Americans, results from the gradual destruction of small islets of insulin-producing cells in the pancreas. Without insulin, the body cannot convert sugars into energy. Even with careful diet and daily doses of insulin, Type 1 diabetes can eventually lead to blindness, kidney failure and strokes.

Past attempts to implant fetal islet cells failed because a small percentage of these cells have antigenic markers that trigger an immune response. "The classic view was that since these antigens were genetically controlled, there was no way to remove them from the cell," says Kevin Lafferty, an Australian-born immunologist who is director of research at the Barbara Davis Center for Childhood Diabetes in Denver. In 1980, however, Lafferty discovered that culturing islet cells in an oxygen-rich environment for a couple of weeks kills those that bear trigger antigens. Says Calvin Stiller, an immunologist at the University of Western Ontario: "This cultured fetal tissue can be transplanted with impunity."