SURVIVAL OF HUMAN COLONY-FORMING CELLS (CFC) AFTER FREEZING

To examine the ability of human macrophage-granulocyte colony-forming cells (CFC) to survive a defined freeze-thaw procedure, we cultured fresh and cryopreserved marrow cells from the same specimens in a methylcellulose system. The cultures were stimulated by two kinds of conditioned medium, fibroblast (FCM) or leukocyte (LCM). We have shown previously that LCM stimulated CFC smaller in size than those stimulated by FCM. Cultures of cryopreserved and fresh cells stimulated by LCM showed no significant difference either in the number of colonies formed or in colony formation kinetics. In contrast with FCM stimulation there was a significant decrease in colony number in cryopreserved specimens, and in addition, the kinetics of colony formation between cryopreserved and fresh specimens were distinctly different. Cryopreserved specimens stimulated with serially diluted FCM or LCM always exhibited their respective kinetic pattern of colony formation. Cell size distribution analysis and morphological examination of fresh and cryopreserved cells revealed that following freeze-thaw there was a marked reduction in cells 9 μm or larger, and that there was a shift in the morphological cell differential from myeloid to lymphoid predominance. From these observations, we concluded that CFC responsive to LCM stimulation survived the freeze-thaw procedure better than CFC responsive to FCM stimulation. © 1979.