Cryopreservation of hematopoietic progenitor cells collected by hemapheresis

Colony-forming units-granulocyte/monocyte (CFU-GM) harvested from normal donors as a byproduct of plateletapheresis can be cryopreserved successfully with 10 percent dimethyl sulfoxide with the use of standard protocols that have been developed for freezing bone marrow. Short-term storage of CFU-GM in polypropylene vials in the liquid phase of liquid nitrogen yielded a recovery rate of 88 +/- 5 percent (mean +/- SEM). Significant loss of committed progenitor cells was not detected until 1 year after freezing (65 +/- 5%). A comparison of CFU-GM recovery with the polyolefin bag technique (107 +/- 13%) was not statistically different from that obtained with polypropylene vials (78 +/- 7%). Although the freezing bags are more expensive and prone to fracture than the vials, they are easier to handle, store, and thaw in the laboratory, and reinfusion to the patient is more convenient. Cryopreservation of CFU-GM harvested from peripheral blood appears feasible in either of two freezing systems.