Study of hematopoietic progenitor cells in thalassemia after bone marrow transplantation.

The hematopoietic committed progenitor cells (BFU-E and CFU-GM) in blood and bone marrow were studied in thalassemic patients before and after bone marrow transplantation. Eighteen transplants were performed in 17 patients with thalassemia. Five were homozygous beta-thalassemia and 12 were beta-thalassemia/hemoglobin E disease. The age ranged from 1.2-14 years (median = 3.4 years). The conditioning regimen comprised busulfan 3.5-4 mg/kg/day for 4 days and cyclophosphamide 50 mg/kg/day for 4 days. Cyclosporin in combination with methotrexate were administered post transplant for GVHD prophylaxis. Before transplantation, BFU-E and CFU-GM in the blood of the patients were significantly higher compared with normal (p < 0.05) but were normal in the bone marrow. Only the CFU-GM in the bone marrow of the successful cases after transplantation recovered to the normal level at the first month through the 12th month whereas the BFU-E were low. Both CFU-GM and BFU-E in the blood were lower than normal after follow up to the 12th month. Inspite of the low number of progenitor cells, there was hematological recovery in the blood of the patients. It may be due to the capacity of the hematopoiesis react to stress which could be amplified the differentiation compartment or the shortened-transit time through the stem cell compartment.