A preliminary study by scientists at the National Institutes of Health and Johns Hopkins says that "mini" stem cell transplantation may safely reverse severe sickle cell disease in adults.
The phase I/II study to establish safety of the procedure describes 10 patients with severe sickle cell disease who received intravenous transplants of blood-forming stem cells.
The transplanted stem cells came from the peripheral blood of healthy related donors matched to the patients' tissue types.
Nine of 10 patients treated with this procedure have normal red blood cells and reversal of organ damage caused by the disease.
Dr. Jonathan Powell said that the intravenous transplant approach for sickle cell disease, caused by a single mutation in the haemoglobin gene, does not replace the defective gene, but transplants blood stem cells that carry the normal gene.
All patients in the study, ranging in age from 16 to 45, were treated at the NIH with what researchers call a non-myeloablative or "mini" transplant, along with an immune-suppressing drug called rapamycin.
Unlike conventional transplant methods, in mini-transplants, lower doses of medication and radiation are used to make room for the donor's cells, the new source for healthy red blood cells in the patient.
According to Powell, side effects, including low white blood cell counts, were few and very mild compared with conventional bone marrow transplantation.
But in nine of the 10, donor cells now coexist with the patients' own cells.
One patient was not able to maintain the transplanted cells long term.
Powell said that by employing the drug rapamcyin, the new approach promotes the coexistence of the host and donor cells.
The study has been published in the New England Journal of Medicine.