Background: The freezing curve currently used for the cryopreservation of autologous peripheral blood stem cell (PBSC) transplants has been empirically determined. Although the use of cryopreserved PBSC is successful and usually leads to rapid hematopoietic recovery, the freezethawingprocess is known to induce a significant amount of cell death. Furthermore, the infusion of DMSO, which is used to protect the cells against damage induced by freezing, can cause morbidity. Therefore, optimizing the current cryopreservation protocol (10% DMSO, slow linear cooling) by using theoretically optimized freezing curves and lower DMSO concentration might improve the results after autologous transplantation. Study Design and Methods: The model of Woelders & Chaveiro was used to predict optimal freezing curves for 5 and 10% DMSO. CD34+ selected and unselected peripheral blood stem cell suspensions were cryopreserved using either the current protocol or the new freezing curves. Postthaw quality was evaluated using cell recovery, colony formation and megakaryocyte outgrowth. Results: Using literature values for water and DMSO permeability, “optimal” freezing curves were calculated. In contrast to the currently used linear freezing curve, the model predicts freezing curves with different freezing rates at different temperatures. With 10% DMSO, the use of the calculated freezing curve resulted in increased post-thaw viability of CD34+ cells, colony formation and megakaryocyte outgrowth. Lowering the DMSO concentration to 5%, resulted, by itself, in improved post-thaw viability and functionality, which was not further improved by using the theoretically optimized freezing curve. Conclusions: Our results indicate that the current cryopreservation method for PBSC can be improved by either lowering the DMSO concentration to 5% or by using the theoretically optimized freezing curve. Infusion of a lower concentration of DMSO and less death cells might reduce the harmful side effects of autologous PBSC transplantation.
|Publication status||Published - 2008|