Sibling Stem Cells May Aid Rare Disorder

A study has shown that using a novel bone marrow transplantation procedure to transfer stem cells of their siblings into patients with chronic granulomatous disease (CGD) significantly improved the functioning of their immune systems. The study, conducted by researchers at the U.S. National Institute of Allergy and Infectious Disease (NIAID; www.niaid.nih.gov), was published in the March 22 issue of The New England Journal of Medicine.

CGD leaves patients vulnerable to infections and inflammatory growths, or granulomas, which can damage the lungs, liver, and other organs. The low-intensity stem cell transplantation procedure uses no radiation and is less risky than conventional stem cell transplantation because only some, rather than all, of the patient's bone marrow cells are knocked out with drugs before the transplant. Thus, patients have a mixture of their own and their sibling's immune cells. T cells, needed to fight infection and facilitate transplantation of the donor stem cells, are reintroduced gradually, starting about one month after the transplant, in order to establish a stable presence of transplanted donor cells.

Of the 10 people enrolled in the study, six had complete engraftment of donor stem cells, and two had partial engraftment. In the median 18 months of follow-up, investigators observed only one serious infection in a CGD patient. "Without the re-infusion of donor T cells, 70-80% of the grafts would be rejected,” noted Dr. Mitchell E. Horowitz, one of the lead researchers. "We had to gradually add back T cells over time, enough to prevent
rejection but not so much as to cause graft-versus-host disease.”




Related Links:
NIAID
New England Journal of Medicine