PROLONGED CRYOPRESERVATION OF HUMAN BONE MARROW

Abstract

The viability of human bone marrow stored for 40-42 mo. in the vapor phase of liquid N was tested. A median of 2 .times. 1010 nucleated cells obtained from 8 patients were concentrated to 1.3 .times. 1010 using discontinuous centrifugation. These were stored in polyolefin bags in volumes of 100-500 ml using 10% dimethyl sulfoxide (DMSO) as a cryoprotectant. Cell number and granulocyte-monocyte colony-forming cell (CFU-c) plating efficiency were determined before feeezing and after thawing, after dilution and removal of DMSO and after 2-4 h of additional incubation. The median difference in cell number and CFU-c plating efficiency after this prolonged storage was -9 and +2%, respectively. Dilution, washing and a 2-h incubation were associated with cell losses of 24, 24 and 19% and increases in CFU-c plating efficiency, ranging 22-79%. The number of viable CFU-c was never significantly lower than the number of CFU-c stored or initially thawed. Vapor phase storage appears to be adequate for prolonged human bone marrow cryopreservation using CFU-c viability as a determinant.