May 16, 2001 -- A new technique makes bone marrow transplants safer. And the Japanese researchers who developed the technique believe it will become a powerful new strategy for the treatment of autoimmune diseases and for organ transplants.
"We think this is a good technique for all bone marrow transplant uses, and also for treatment of autoimmune diseases," study leader Susumu Ikehara, MD, PhD, tells WebMD. Ikehara is director of the transplant center at Kansai Medical University in Osaka, Japan.
A major problem with bone marrow transplantation is that transplants from other people's bone marrow often attack the body of the person receiving the transplant. The new technique described in the May 15 issue of the journal Bloodgreatly reduces this graft-vs.-host disease, or GVHD, in monkey studies.
"If you use [our] technique, even mismatched bone marrow is all right and there is no GVHD," Ikehara says.
Bone marrow is rich in stem cells, which can replenish the blood and other damaged parts of the body. Bone marrow transplants offer a way to restore the marrow after it has been wiped out by drugs or radiation. The technique was first used to help cancer patients who underwent highly toxic chemotherapy for their disease. After aggressive chemotherapy, patients would be "rescued" with bone marrow transplants.
Today researchers are using a similar strategy to reboot the immune systems of people with autoimmune diseases -- illnesses in which the body is attacked by it's own immune system. The idea is to wipe out immune cells that have gone wrong and to replace them with new cells.
Ikehara and co-workers invented a new method of collecting stem cells directly from the bone marrow, instead of trying to filter them out of the blood stream. The idea is to a pure collection of stem cells. Even after filtering, as many as 20% of the cells obtained from the blood are fully mature immune cells -- and when they are put back into a person with an autoimmune disease, they go right back to attacking the body. Ikehara says that the new technique gets stem cells that are more than 98% pure.
Usually the stem cells are returned to the body by infusing them into the blood. But many of these cells get lost on their way back to the marrow. Ikehara's team shows that injecting the stem cells directly into the bone marrow also yields much better results. In mouse studies, animals with autoimmune disorders were completely cured with the new technique.
Robert A. Brodsky, MD, an assistant professor of oncology at Johns Hopkins University Medical School, has been conducting clinical trials of bone marrow transplant for autoimmune disease. Brodsky says that even though new techniques reduce the number of immune cells in the transplant, too many still may be left.
"You still are giving back millions of [immune cells] that are actually causing the autoimmune disease," Brodsky tells WebMD. "The key to me is [to] get it to zero [immune cells]. The way you get it to zero is you don't use stem cells at all."
Brodsky says that stem cells are resistant to a drug used to wipe out the rest of the bone marrow. By giving high doses of this drug to patients with autoimmune disease, he says it is possible for the remaining stem cells to reboot the immune system -- without the need for transplant.
"There are two diseases now where this is the up-front therapy: aplastic anemia and lupus," he says. "The results have been so compelling that we have stopped transplanting adults with aplastic anemia, even if they have a marrow-donor match. For patients with lupus, this must still be done in the context of a clinical trial."
But Brodsky says that stem cell transplants undoubtedly will have a role in the treatment of other autoimmune diseases. "There is no question that these approaches, even stem cell transplant, are going to play a role in the future," he says. "What we don't know is what the ideal regimen is, and when to do stem cell transplants or not. And we don't know where in each disease this will play a role -- whether it should be used up front or only in [hard-to-treat] cases."