Microprocessor-controlled vs. "dump-freezing"platelet and lymphocyte cryopreservation: a quantitative and qualitative comparative study.
BACKGROUND/AIM: Thermodynamical and cryobiological parameters responsible for cell damages during cryopreservation (cryoinjuries) have not yet been completely explained. Thus, freezing procedures should be revised, exactly optimized to obtain an enhanced structural and functional recovery of frozen-thawed cells. The aim of this study was to compare microprocessor-controlled (controlled-rate) with the compensation of the released fusion heat and "dump-freezing" (uncontrolled-rate) of the platelet and lymphocyte cryopreservation efficacy. METHODS: Platelet quantitative recovery (post-thaw vs. unfrozen cell count), viability (using hypotonic shock response--HSR), morphological score (PMS), ultrastructural (electron microscopy) properties and expression of different surface antigens were investigated. In lymphocyte setting, cell recovery and viability (using trypan blue exclusion test) as well as functionality (by plant mitogens) were determined. Controlled-rate freezing and uncontrolled-rate cryopreservation were combined with 6% (platelets) and 10% (lymphocytes) dimethyl sulfoxide (DMSO). RESULTS: Platelet recovery and functionality were superior in the controlled-rate system. The majority of surface antigen expression was reduced in both freezing groups vs. unfrozen cells, but GP140/CD62p was significantly higher in controlled-rate vs. uncontrolled-rate setting. Controlled-rate freezing resulted with better lymphocyte recovery and viability (trypan blue-negative cell percentage). In mitogen-induced lymphocyte proliferative response no significant intergroup difference (controlled-rate vs. uncontrolled-rate) were found. CONCLUSION: The data obtained in this study showned the dependence of cell response on the cryopreservation type. Controlled-rate freezing provided a superior platelet quantitative and functional recovery. Lymphocyte recovery and viability were better in the controlled-rate group, although only a minor intergroup difference for cell proliferative response was obtained.