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.