Background: Previous in vitro studies have demonstrated decreased apoptosis and necrosis in peripheral blood progenitor cells (PBPCs) cryopreserved with 5 percent instead of 10 percent dimethyl sulfoxide (DMSO). This study was carried out to investigate whether these in vitro findings were supported by clinical data concerning hematopoietic engraftment after autologous stem cell transplantations with PBPCs cryopreserved with 5 and 10 percent DMSO.
Study design and methods: During a 6-year period, 103 consecutive patients with newly diagnosed multiple myeloma (MM; n = 58) and lymphoma (n = 45) were transplanted with autologous PBPCs. Throughout the first part of the period cells were cryopreserved with 10 percent DMSO and later with 5 percent. A retrospective comparison was carried out of the clinical results for these two groups.
Results: No significant difference in median time to neutrophil and platelet (PLT) engraftment was demonstrated for MM and lymphoma patients transplanted with PBPCs cryopreserved with 5 or 10 percent DMSO. Time until neutrophil counts of more than 0.5 x 10(9) per L was 10 days both for the 5 and 10 percent MM groups and 12 days for both the 5 and the 10 percent lymphoma patients. Median time until stable PLT counts of more than 20 x 10(9) per L was 11 days in all four groups. In addition, transfusion requirements and duration of days admitted to hospital did not differ between the groups.
Conclusion: The routines for cryopreservation of autografts vary considerably between transplantation centers, and this makes it difficult to compare different clinical studies. Our results suggest that cryopreservation with 5 percent DMSO alone followed by storage in nitrogen is a simple, highly standardized, and safe procedure for cryopreservation of autologous stem cell graft.