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.

The optimal protocol for mobilization of hematopoietic stem cells in patients with lymphoid malignancies has not been determined so far. We retrospectively analyzed the efficacy and safety of Ara-C at a dose of 1.6 g/m 2 compared with CY at a dose of 4.0 g/m 2 , both combined with filgrastim. Seventy and forty-five patients, respectively, were included, among whom 60% were defined as 'predicted poor mobilizers'. The use of Ara-C was associated with significantly higher peak number of circulating CD34þ cells compared with CY (Po0.0001). In the Ara-C group, 95% of patients with multiple myeloma (MM) collected at least 5 Â 10 6 CD34 þ cells/kg required for tandem transplantation, and 97% of lymphoma patients collected at least 2 Â 10 6 CD34 þ cells/kg, needed for a single autologous hematopoietic SCT (autoHSCT), which was achieved with a single leukapheresis in 91% of cases. Results for the CY group were significantly inferior (Po0.0001). No patient mobilized with Ara-C experienced febrile neutropenia, whereas 35% required platelet transfusions. Among patients who proceeded to autoHSCT, the time of both neutrophil and platelet recovery was significantly shorter for those mobilized with Ara-C than CY. We conclude that intermediate-dose Ara-C þ filgrastim is a very effective and relatively safe mobilization protocol for patients with lymphoid malignancies.Bone Marrow Transplantation (2013) 48, 915-921;

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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.