RESUMO
BACKGROUND AND OBJECTIVES: The procedure of autologous hematopoietic stem/progenitor cell transplantation requires cryopreservation. Addition of DMSO is necessary to secure the viability of such cells, but this solvent is potentially toxic to stem cells' recipient. 10% DMSO solution is used by the majority of transplant centres. The aim of our study was to test if DMSO concentration might be reduced without negative impact on cell recovery and clonogenicity. MATERIALS AND METHODS: Samples were prospectively collected from 20 patients. Small volumes of leukapheresis products were frozen with different cryoprotective mixtures, containing 10%, 7·5%, 5% and 2·5% DMSO, respectively. The quality of cryoprotective mixtures was evaluated based on recovery, viability and clonogenic potential of hematopoietic stem cells after defreezing. RESULTS: Reduction in DMSO concentration to 7·5% or lower was associated with decreased recovery of nucleated cells. In contrast, the number of colonies was highest for 7·5% DMSO with significant differences when compared to 10% DMSO solution. CONCLUSION: Reduction in DMSO concentration from 10% to 7·5% may have favourable impact on hematopoietic recovery after autologous transplantation. The findings require confirmation in a clinical setting.