Initial Success In Transplant Given To Ailing Fetus
WASHINGTON (AP) _ A pioneering transplant of fetal tissue into a developing fetus to cure a genetic ailment shows initial signs of success, doctors said Wednesday.
Esmail Zanjani of the University of Nevada in Reno said the transplanted tissue has taken hold in the recipient, who was born in November. Five to 10 percent of the child’s blood-making cells are descendants of the transplanted cells, he said.
″Has it succeeded to the point of curing? We don’t know yet,″ Zanjani said at the Eighth International Congress of Human Genetics.
Further tests will be required to determine whether the child, afflicted with a severe genetic abnormality called Hurler syndrome, is developing symptoms of the disorder, he said.
Such transplants could theoretically be used to treat a wide variety of genetic disorders, said Dr. Mitchell Golbus of the University of California, San Francisco.
The case highlights the thorny issue of whether research using fetal tissue should be allowed. The government has opposed fetal tissue research over the strong protests of medical researchers.
Transplants of fetal tissue into mice, cats and sheep have been successful, but transplants of adult tissue into animal fetuses have not succeeded, said Zanjani.
Golbus has attempted three transplants of adult tissue into fetuses to cure genetic disorders. Two failed, and in the third case the parents elected to terminate the pregnancy before the success of the procedure was known, Golbus said.
Zanjani said he believed that the transplants failed because they used adult rather than fetal tissue.
The child whose transplant is showing signs of success was the focus of Congressional hearings in April on the subject of fetal tissue research. The child’s parents, Guy and Terri Walden of Houston, urged that research on fetal tissue be allowed.
″Stopping this tissue from being used isn’t going to bring (the aborted fetus) back,″ Guy Walden told a congressional committee. ″What about the moral question of if we can help a child - but we don’t?″
The Waldens have lost two previous children to Hurler syndrome, which causes skeletal problems and severe mental retardation. The symptoms are all due to a genetic abnormality that results in the loss of a single critical enzyme in the body.
″Using fetal tissue to treat a fetus hasn’t come up before,″ said Zanjani. ″This is to prevent an abortion from occurring.″
Zanjani said the government’s objection to fetal tissue research is that the demand for such tissue might encourage abortions. He dismissed that idea.
Zanjani said that tissues from a single fetus could be used to treat four or five fetuses.
″I know it’s crude to say it - one life to save five, if successful,″ he said.
A transplant of blood-forming cells into a fetus is far cheaper than a bone-marrow transplant after birth, he said.
In the case of the fetus, liver cells - which produce blood cells before bone marrow develops - are injected into the belly at a cost of perhaps $1,000 or $2,000, Zanjani said.
A bone-marrow transplant is an extremely difficult procedure that can cost about $200,000, he said.
The cell transplant is theoretically more likely to be successful because the fetus, early in its development, has not yet developed an immune system to reject the transplanted cells.
Although the Walden child’s own cells were not completely replaced by the transplanted cells, the child may have acquired enough transplant cells to prevent disease, Golbus said.
If 5 percent to 10 percent of the transplanted cells survive over the long term, they should produce enough of the enzyme that is missing in Hurler syndrome to prevent symptoms, Golbus said.