IN VIVO SURVIVAL OF PLATELET CONCENTRATES FOLLOWING RAPID FREEZING AND THAWING

The in vivo survival of rapidly frozen and thawed homologous rabbit platelet concentrates with and without protective agents, was determined by labeling the platelets with Na253Cro4. The results were compared with a control group of unfrozen fresh platelets. Droplets of platelet concentrates, without additive, were cooled at rates in excess of 100°C per sec by direct contact with a surface of liquid helium. The platelets appeared to be almost completely destroyed. When droplets of platelet concentrates without additive were frozen in liquid nitrogen with a cooling rate of more than 10°C per sec, the in vivo survival 30 min after transfusion was 63.4% of the unfrozen control group and 36.3% after 1 day. When 5% DMAC in combination with 5% dextrose was added as a protective substance, the survival after 30 min was 75.0% of the control group and 78.2% after 1 day. Ten per cent glycerol as an additive was significantly les effective than DMAC-dextrose and appeared less effective than those specimens in which no additives were used. A warming rate of 40°C per sec afforded protection relative to a warming rate of 6°C per sec, in which platelet destruction was heavy. © 1969.