Optimum temperature for maintaining the viability of CD34+ cells during storage and transport of fresh haematopoietic progenitor cells

The optimum conditions for storage and transport of freshly harvested hemopoietic progenitor cells (HPC) in the liquid state is uncertain. It is not specified in commonly applied standards for stem cell transplantation. We used a viable CD34 assay to determine the optimum temperature for maintaining progenitor cell viability in freshly harvested bone marrow and peripheral blood stem cells. Our aim was to identify standardized conditions for storage and transport of marrow or peripheral blood products that would optimize CD34 recovery leading to better transplant outcomes. Samples were aseptically removed from 46 fresh HPC harvests (34 PBSC and 12 BM) and stored at refrigerated temperature (2°–8° C), room temperature (18°–24° C) and 37° C, for up to 72 hours. Samples were analysed for viable CD34+ cells/ml at 0, 24, 48, and 72 hours. The mean viable CD34+ yield prior to storage was 7.7 × 106/Kg (range 0.7–30.3). The mean loss of viable CD34+ cells in HPC products at refrigerated temperature was 9.4%, 19.4%, and 28% at 24, 48, and 72 hours, respectively. In contrast, the mean loss of viable CD34+ cells at room temperature was 21.9%, 30.7%, and 43.3% at 24, 48, and 72 hours, respectively. No viable CD34+ cells remained after storage at 37° C for 24 hours. Only PBSC products and not BM showed temperature related loss of CD34 viability. Greater loss of viable CD34+ cells was observed for allogeneic PBSC compared to autologous PBSC. These results demonstrate that the optimum temperature to maintain the viability of CD34+ cells during overnight storage and transport of freshly harvested HPC is 2°–8° C. These findings allow for the development of standard guidelines for HPC storage and transport.