Mobilization, collection, and processing of peripheral blood stem cells in individuals with sickle cell trait

Mobilized peripheral blood is increasingly used as the source of hematopoietic stem cells for allogeneic transplantation, currently the only curative approach for sickle cell anemia. However, the safety and feasibility of stem cell mobilization in individuals with sickle cell trait (SCT) has not been documented. This study is a prospective controlled trial to evaluate the safety and feasibility of peripheral blood stem cell (PBSC) mobilization in 8 SCT subjects and 8 control subjects matched for age and race. Mobilization with filgrastim 10 microg/kg subcutaneous daily for 5 days was followed by 12-L apheresis on the fifth day. Filgrastim administration was accompanied by similar symptoms in all subjects; no untoward adverse events occurred in either group, including sickle cell crises. CD34+ cell mobilization response was not significantly different between SCT and control subjects. Median CD34+ cell content was also similar in PBSCs collected from SCT versus control subjects, 6.8 versus 3.9 x 10(6) CD34+ cells/70 kg, P =.165. Red cell depletion from SCT products was not possible by using hydroxyethyl starch sedimentation but was achievable with ammonium chloride lysis. There was no evidence of gelling of SCT products after thaw, and no difference in cell recovery was seen among red cell-depleted versus nondepleted products. Cryopreservation in 5% dimethyl sulfoxide/6% pentastarch was associated with superior cell recovery (both SCT and control subjects) compared with 10% dimethyl sulfoxide (P =.001). The study concluded that filgrastim mobilization, large volume apheresis, processing, and cryopreservation appears to be safe in donors with SCT, allowing PBSC use for transplantation in patients with sickle cell anemia.