Many people worldwide suffer from sickle cell disease, which is an inherited blood disorder arising from a genetic defect. As a result, the structure of hemoglobin in sickle cell patients differs from that in healthy people - red blood cells become sickle-shaped, stiff and sticky. The cells affected by the disease can block blood flow, cause severe pain, organ damage, and stroke.
There is no cure for sickle cell disease except for bone marrow transplants. But apart from being scarce, bone marrow transplants, although showing success in children, require toxic pre-conditioning in adults. Normally, chemotherapy is used to destroy all bone marrow of the patient, which is then replaced with donor’s bone marrow. After the transplantation, the recipients usually need to take immunosuppressants for months to a few years, which causes numerous side effects.
A team at NIH’s Clinical Center in Bethesda, Maryland, aimed to test modified procedure in adults suffering from sickle cell disease. During the procedure, the researchers planned to kill only part of the patient’s stem cells, to transplant donor’s bone marrow stem cells and to use less toxic medications over and after the procedure. The results were published online in the Journal of the American Medical Association.
Between 2004 and 2013, the study enrolled 30 patients aged 16 to 65 with severe sickle cell disease. The team has found that stem cell transplantation reversed the disease in 26 of 30 patients (87%). They reported normal hemoglobin, fewer hospitalizations, and lower use of pain killers. After a median follow up of 3.4 years, the researchers did not observe graft-versus-host disease—when donor cells attack the recipient’s ones—in these patients, and 15 of them stopped taking immunosuppressants a year after the transplant. The treatment was unsuccessful in 4 patients who faced some complications.
The success of the study means that the technique can be used even for adult patients as well due to lower doses of immunosuppressants and less-toxic partial stem cell transplant applied.