Researchers have for the first time performed a successful bone marrow transplant to cure sickle cell disease in adults, a feat that could expand the procedure to more of the 70,000 Americans with the disease — and possibly some other diseases as well.
About 200 children have been cured of sickle cell with transplants, but the procedure is considered too harsh for adults with severe sickle cell disease. Now a team from the National Institutes of Health and Johns Hopkins University reports in today's New England Journal of Medicine that it has developed a much less toxic transplant procedure and used it to cure nine of the first 10 patients studied.
"We really don't have anything else to offer patients with sickle cell disease" who do not respond to hydroxyurea, the only drug useful in treating it, said Dr. John F. Tisdale of the National Heart, Lung and Blood Institute, the senior author of the paper. "It's really satisfying to perform a therapy that … gets rid of the disease."
The principal drawback to the procedure is that not enough sickle cell patients have a healthy sibling who is a compatible donor. A sibling donor is necessary in sickle-cell-caused transplants to ensure the marrow isn't rejected by its new host. The team plans to attempt the procedure using unrelated donors and parents.
Sickle cell disease, which affects primarily black people, is caused by a genetic mutation that makes red blood cells assume a sickle shape, hindering their ability to carry oxygen and causing them to clog blood vessels. In severe cases, the disease causes stroke, severe pain, and damage to multiple organs — especially the lungs, kidneys and liver. It can be fatal.
Patients receive frequent transfusions to provide competent red cells, but that leads to a toxic buildup of iron and can sensitize patients to foreign red cells. Hydroxyurea, which stimulates cells to produce a form of hemoglobin that is normally present only in fetuses, has a protective effect, acting like a transfusion to thin out the sickled cells. Many patients fail such drug therapy however.
Bone marrow transplantation "is the only curative treatment for sickle cell disease," wrote Dr. Miguel R. Abboud of the American University of Beirut Medical Center in an editorial accompanying the report.