Collection and use of peripheral blood stem cells in very small children.

Collections of peripheral blood stem cells (PBSC) from children weighing less than 25 kg have been limited by concern about citrate toxicity. We developed a modified collection technique on the Fenwal CS3000 blood cell separator and used it in three children weighing 8.3, 20 and 24 kg with neuroblastoma involving the marrow. The saline prime was discarded as a mixture of 250 ml red cells, 100 ml fresh frozen plasma, and 100 ml 5% albumin was run into the separator. Heparin (1500 units/h) was used to supplement ACD, which was infused at a low rate (1:25-1:32 vs blood, vs the usual 1:13). No serious difficulties were encountered during or after the collections. A total of 5.7, 4.8 and 6.4 x 10(8) mononuclear cells/kg were collected in six procedures per patient. After cell cryopreservation and patient preparation using high-dose chemotherapy, the cells were thawed in 37 degrees C saline and infused without incident. Hematopoietic recovery was observed, and one of the patients remains in clinical remission after 11 months of follow-up. The addition to previously developed procedures of the use of partial albumin prime, low citrate anticoagulation, and heparin allows convenient and safe collection of PBSC in extremely small children, and these PBSC are effective.