Collection and transplantation of peripheral blood stem cells in very small children weighting 20 kg or less

The safety and efficacy of harvesting peripheral blood hematopoietic stem cells (PBSC) were evaluated in 38 children weighing 20 kg or less, with the smallest patient weighing 7 kg. The patients had a median age of 42 months and included 26 children with acute leukemias or lymphoma and 12 with various solid tumors. A total of 81 aphereses were performed, mostly in the recovery phase of chemotherapy, with or without granulocyte colony-stimulating factor, using a CS-3000 cell separator and regular procedure no. 3. Blood was withdrawn at a mean rate of 30 mL/min (range, 17 to 46 mL/min) through a temporary radial arterial catheter (20 to 24 guage) and returned through a larger catheter in a peripheral vein. Morbidity related to PBSC harvest was low and all aphereses were completed within 3 hours. The volume of blood per kilogram processed for each apheresis ranged from 85 to 615 mL (median, 270 mL). The median number of colony-forming units-- granulocyte-macrophage (CFU-GM) and CD34+ cells collected were, respectively, 34 x 10(4)/kg and 15 x 10(6)/kg per apheresis and 126 x 10(4)/kg and 31 x 10(6)/kg per patient. Thirty-three patients (87%) required only a single apheresis to collect the minimum requirement of 10 x 10(4) CFU-GM/kg, including 28 patients (74%) from whom 30 x 10(4) CFU-GM/kg was obtained in a single apheresis. Twenty-three of the patients subsequently underwent autografts with PBSC. The median number of days required to achieve an absolute granulocyte count of 0.5 x 10(9)/L and a platelet count of 50 x 10(9)/L were, respectively, 10 (range, 6 to 15) and 14 (range, 9 to 46). The patients remained dependent on platelet transfusion support for a median of 10 days (range, 5 to 35). Thus, harvesting PBSC in very small children with active cancers is effective and safe and does not involve the risk of anesthesia or multiple invasive marrow aspirations.