Culture conditions affect the ability of ex vivo expanded peripheral blood progenitor cells to accelerate hematopoietic recovery

Objective. The aim of this study was to evaluate the effect of various ex vivo expansion conditions on the cell products and their ability to accelerate hematopoietic recovery in patients undergoing stem cell transplantation. Patients and Methods. Unselected peripheral blood progenitor cells (PBPCs) from 43 breast cancer patients were seeded into gas-permeable bags containing serum-free media, granulocyte colony-stimulating factor, stem cell factor, and pegylated megakaryocyte growth and development factor. Between 2 and 24 X 10(9) PBPCs were cultured at 1, 2, or 3 X 10(6) cells/mL for 9 to 14 days. The expanded PBPCs and cryopreserved PBPCs containing at least 5 X 101 CD34(+) cells/k-g were infused following completion of high-dose chemotherapy. Results. Increasing culture duration from 9 to 11-14 days significantly improved the expanded cell yield and fold expansion, whereas increasing PBPC seeding density above 101 cells/mL had the opposite effect. The expanded cell dose was the only culture variable that correlated significantly with the time to neutrophil recovery (r = -0.66; p = 0.0001). Study patients had significantly faster neutrophil (p < 0.0001) and platelet (p = 0.001) recovery, reduced red cell transfusions (p = 0.01), and shorter hospital stays (p < 0.0001) than historical controls. The most clinically efficacious expanded cell product was seeded with 1010 PBPCs at 101 cells/mL, then cultured for 11 days. The six patients in that cohort experienced 2.8 +/- days of absolute neutropenia and had neutrophil recovery 5.7 +/- 0.8 days post-transplant; none had a neutropenic fever or required intravenous antibiotics. Conclusion. Unselected PBPCs expanded ex vivo significantly impact hematopoietic recovery following high-dose therapy. Optimization of the expansion conditions enhances the efficacy of this cell product. (C) 2002 International Society for Experimental Hematology. Published by Elsevier Science Inc.