'Half-match' bone marrow transplants wipe out sickle cell disease in selected patients
Sep 20, 2012 - 4:00:00 AM
In a preliminary clinical trial, investigators at Johns Hopkins have shown that even partially-matched bone marrow transplants can eliminate sickle cell disease in some patients, ridding them of painful and debilitating symptoms, and the need for a lifetime of pain medications and blood transfusions. The researchers say the use of such marrow could potentially help make bone marrow transplants accessible to a majority of sickle cell patients who need them.
After a median follow-up of two years, the transplants successfully eliminated sickle cell disease in 11 of 17 patients. Three were fully matched to their donors and eight received half-matched donor marrow. All 11 patients are free of painful sickle cell crises and 10 no longer have anemia. There were no deaths and no unexpected toxicities.
Six of the 11 patients (all half-matched) have stopped taking immunosuppressive drugs, although some still require narcotics for chronic pain because of sickle cell-related organ damage. Blood tests on the six patients show that their red cells are now completely derived from their donor's marrow.
Patients with severe sickle cell disease (SCD) face shortened life spans, intractable pain and eventual organ damage as a result of their disease, an inherited disorder caused by a mistake in the oxygen-carrying hemoglobin molecules in red blood cells. The flawed genetic code stiffens red cells, and shapes them into a pronged sickle that clump and stick into blood vessel walls, cutting off blood and oxygen to tissues and organs throughout the body.
SCD occurs in approximately one in 400 African Americans, and rarely in Caucasians. An estimated 100,000 people are currently living with sickle cell disease in the U.S.
Most patients die before age 50, and many suffer poor quality of life with frequent episodes of off-the-charts pain, and an increased risk for kidney failure, stroke, deep-vein thrombosis, and lung disease.
Treatments include blood transfusions and a drug, hydroxyurea. Many patients use narcotics to control severe pain and have repeat hospitalizations. Bone marrow transplants have been successful in curing some cases, but matching donors are rare and the procedure itself poses risk.
In the current study, 17 patients at the Johns Hopkins Hospital were offered bone marrow transplant options, including the use of half-matched donor marrow to try and replace their sickled blood cells with new, healthy ones. The transplants were successful in 11 of the patients, of whom eight were only half-matches. Results of the trial were published in the Sept. 6 early online edition of
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