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

BACKGROUND: 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. STUDY DESIGN AND METHODS: 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. RESULTS: Before storage, the median number of CD34+ cells was 1.46 × 10(6) (range, 0.01–54.05 × 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 × 10(5) (range, 0.02–157.49 × 10(5)) per kg of BW before cryopreservation and significantly (p < 0.001) lower, 0.83 × 10(5) (range, 0–220.36 × 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. CONCLUSION: 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.