Comparison of CD34+ cell numbers and colony growth before and after cryopreservation of peripheral blood progenitor and stem cell harvests: influence of prior chemotherapy.

Abstract

Quantitative determination of hematopoietic progenitor cells is a major issue in peripheral blood progenitor and stem cell collection and transfusion, although the extent is still an object of discussion. In 116 leukapheresis collections from 42 patients, immunophenotyping for CD34+ cells, evaluation of in vitro proliferative capacity by a colony-forming unit-granulocyte-macrophage (CFU-GM) assay, and viability assessment by trypan blue exclusion were performed before and after storage in liquid nitrogen at -196 degrees C. Before storage, the median number of CD34+ cells was 1.46 x 10(6) (range, 0.01-54.05 x 10(6)) per kg of body weight (BW). There was no significant difference between precryopreservation and postcryopreservation numbers. The median number of CFU-GM was 2.25 x 10(5) (range, 0.02-157.49 x 10(5)) per kg of BW before cryopreservation and significantly (p < 0.001) lower, 0.83 x 10(5) (range, 0-220.36 x 10(5)) per kg of BW, after cryopreservation. The correlation coefficient of prestorage and poststorage values was 0.92. The median ratio of poststorage and prestorage values was 42.3 percent (0-304.8%). Male patients who underwent intense chemotherapy (> 5 cycles) showed a significantly lower ratio of postcryopreservation and precryopreservation CFU-GM values than other patients (p = 0.0047). A strong linear correlation was determined between the number of CD34+ cells per kg of BW and the number of CFU-GM per kg of BW before and after cryopreservation. A viability below 50 percent predicted a high loss of in vitro proliferative capacity, while a viability above 50 percent did not correlate with a high ratio of CFU-GM from after and before cryopreservation. A good correlation between the variables used for characterization of peripheral blood progenitor cells--the number of CD34+ cells and the number of CFU-GM--was observed. Viability assessment by trypan blue exclusion does not seem to be a substitute for assays evaluating in vitro proliferative capacity.