But when doing the new bone marrow transplants, the researchers noted that not all of the patient's own marrow was wiped out. Some remained and seemed to co-exist with the donor marrow without causing problems, Tisdale said.
"That meant we didn't necessarily have to kill the entire bone marrow of the patient to make this work," Tisdale said, opening the possibility of using an even less toxic means of preparing the body for transplant.
Though most patients in the study are still taking immune-suppressant drugs, researchers hope to eventually wean them off the medications.
Dr. Miguel Abboud, a pediatric hematology/oncology specialist and a professor of pediatrics at the American University of Beirut Medial Center, in Lebanon, said the new protocol is promising, especially since it could eventually include those who don't have an HLA-matched sibling.
"The findings are very significant because adults with very severe sickle cell disease have decreased life expectancy and multiple morbidities but have limited therapeutic options," said Abboud, who wrote an accompanying editorial. "In the past these patients were excluded from transplant studies as they are very poor candidates for high dose chemotherapy regimens. This study makes it possible to offer this subset of patients with severe sickle cell disease stem cell transplants."
Dr. Lakshmanan Krishnamurti, a pediatric hematologist/oncologist at the University of Pittsburgh and director of the Sickle Cell Program at Children's Hospital of Pittsburgh, has done bone marrow transplants in children, also using a less toxic protocol.
"This is an important paper and a big step forward for the field," Krishnamurti said. "Now we are able to say, 'OK, young adults or not so young adults can be transplanted successfully.' That is a very big deal."
There's more on sickle cell disease at the Sickle Cell Disease Association of America.
SOURCES: John Tisdale, M.D., senior investigator, molecular and clinical hematology branch, U.S. National Heart, Lung, and Blood Institute and U.S. National Institute of Diabetes and Digestive and Kidney Diseases, U.S. National Institutes of Health, Bethesda, MD; Lanetta Jordan, M.D., M.P.H., chief medical officer, Sickle Cell Disease Association of America, Baltimore; Miguel Abboud, M.D., professor of pediatrics, American University of Beirut Medical Center, Beirut, Lebanon; Lakshmanan Krishnamurti, M.D., pediatric hematologist/oncologist, University of Pittsburgh and director, Sickle Cell Program at Children's Hospital, Pittsburgh, Pa.; Dec. 10, 2009, New England Journal of Medicine