Better preservation of early hematopoietic progenitor cells when human peripheral blood progenitor cells are cryopreserved with 5 percent dimethylsulfoxide instead of 10 percent dimethylsulfoxide

BACKGROUND: Previous studies have demonstrated that cryopreservation of PBPCs in 5 percent DMSO is superior to 10 percent DMSO with regard to CD34+ cell viability and preservation of mature clonogenic cells. Nevertheless, preservation with 5 percent DMSO of primitive progenitors responsible for long-term post-transplant reconstitution must be characterized before this decreased concentration is further evaluated in clinical studies of autotransplantation in cancer patients. STUDY DESIGN AND METHODS: PBPCs from 15 patients with malignant diseases were cryopreserved in 5 and 10 percent DMSO and stored in liquid nitrogen for at least 14 months before the preservation of long-term culture-initiating cells (LTC-ICs) was evaluated. RESULTS: LTC-IC survival was significantly better after PBPC cryopreservation with 5 percent DMSO instead of 10 percent DMSO (median, 43 colonies vs. 7 colonies, p = 0.003) The frequency of 5-week LTC colony-forming cells showed a significant correlation with the percent-age and number of viable CD34+ cells but not to the number of mature colony-forming cells in cryopreserved PBPCs. CONCLUSION: Primitive progenitor cells in PBPC autografts from patients with malignant disorders can be cryopreserved with 5 percent DMSO, and the number of viable CD34+ cells can be used as a marker for the number of primitive progenitors in the graft.