Apoptosis: a method for evaluating the cryopreservation of whole blood andperipheral blood mononuclear cells

We sought to compare the effect of cryopreservation and storage at -30 degr eesC, -70 degreesC and - 150 degreesC of human whole blood versus matched p eripheral blood mononuclear cell (PBMC) samples using apoptosis as an indic ator of cell fitness. Following 10 weeks of storage the samples were thawed and assessed for viability (trypan blue exclusion), levels of apoptosis (u sing the nuclear stain bis-benzimide) and cell function (ability to be tran sformed by Epstein-Barr virus, EBV). When comparing storage temperatures, t he Levels of apoptosis in whole blood and PBMC samples stored at -30 degree sC were significantly higher than the values for samples stored at -70 degr eesC or - 150 degreesC (P<0.004). Whole blood samples stored at -150<degree s>C had significantly less apoptosis than those stored at -70 degreesC (P<0 .03). A comparison of the cell preparations showed that at all three storag e temperatures there was significant sample deterioration (viability, apopt osis, and function) in whole blood relative to PBMC samples. This study ind icates that careful consideration should be given to storage conditions and that apoptosis can be used as a sensitive measure of cell fitness followin g cryopreservation. (C) 2000 Elsevier Science B.V. All rights reserved.