Isolation and storage of peripheral blood hematopoietic stem cells for autotransplantation into children with cancer

Peripheral blood stem cells (PBSC) were collected for autotransplantation by a total of 46 continuous-flow leukaphereses in 17 children with various types of cancer in whom the stem-cell pool had been expanded by chemotherapy. As the cells collected by leukapheresis were contaminated with many visible cell clumps, platelets, and erythrocytes, they were separated from the platelet-rich plasma (PRP) by slow-speed centrifugation and fractionated on a discontinuous gradient of Percoll. All the hematopoietic progenitors (CFU-GM, CFU- GEMM) in the starting samples were recovered at the interface of 40% and 60% Percoll solutions largely free of other cellular components and with a substantial reduction in volume. The separation and freezing procedures could be completed within three hours after obtaining cells by leukapheresis. After their fractionation and storage, these PBSC were shown to be able to reconstitute normal hematopoiesis in ten children with poor prognosis leukemia or neuroblastoma for whom no HLA- compatible marrow donors were available and who had been subjected to marrow-ablative therapy. This separation procedure is simple, efficient, and readily available and can be used for children as a routine procedure for PBSC autotransplantation.