Reduction of DMSO concentration in cryopreservation mixture from 10% to 7.5% and 5% has no impact on engraftment after autologous peripheral blood stem cell transplantation: results of a prospective, randomized study.

The procedure of autologous peripheral blood stem cell transplantation (autoPBSCT) requires cryopreservation of cells in a mixture containing dimethyl sulfoxide (DMSO). DMSO is necessary to secure cell viability, however, its infusion may be toxic to stem cell recipient. The aim of this study was to prospectively evaluate the impact of DMSO concentration on engraftment after autoPBSCT.One-hundred-fifty patients were randomly assigned to one of three study arms; their leukapheresis products were cryopreserved in 10%, 7.5% or 5% DMSO. The study groups did not differ with regard to the diagnosis (mainly lymphomas and multiple myeloma), age, conditioning regimen, and the number of transplanted hematopoietic stem cells. 143 patients were treated with autoPBSCT. The frequency of adverse effects during and shortly after infusion was the lowest in 5% DMSO arm (p = 0.02 compared to 10% DMSO). 4 patients died due to infection before the engraftment. The median time to leukocyte and neutrophil recovery was 10 days in all study groups (p = 0.36 and p = 0.2). As well, the median day of platelet recovery was the same for all DMSO concentrations and equaled 15 days (p = 0.61).In view of these results, 5% DMSO mixture may be considered a new standard in cryopreservation of hematopoietic stem cells.

A faster reconstitution of hematopoiesis after autologous transplantation of hematopoietic cells cryopreserved in 7.5% dimethyl sulfoxide if compared to 10% dimethyl sulfoxide containing medium.

Our previous in vitro studies proved a higher clonogenic potential of peripheral blood progenitor cells cryopreserved in 7.5% dimethyl sulfoxide (Me2SO) than in 10% Me2SO containing medium. Based on this findings 7.5% Me2SO cryopreservation medium was introduced to our protocol and both the hematopoietic recovery and infusion-related toxicity were compared with that obtained with standard 10% Me2SO containing solution. Two cohorts of consecutive patients treated with autologous hematopoietic stem cell transplantation were included in the analysis: 56 patients with PBPCs cryopreserved in 7.5% Me2SO solution and 52 patients who obtained cells cryopreserved in 10% Me2SO. Both study groups did not differ significantly with regard to age, diagnosis, and the number of transplanted CD34(+) cells. The time to leukocyte recovery was shorter for patients in the 7.5% Me2SO treated group than in the 10% one. Reconstitution of platelets and the frequency of adverse events did not differ in both groups. Reduction of Me2SO concentration from 10% to 7.5% in cryoprotective mixture has a beneficial impact on leukocyte recovery. These findings require verification in a prospective, randomized trial.