Platelet preservation by freezing. Use of dimethylsulfoxide as cryoprotective agent.

Variables important in the preservation of platelets by freezing with dimethylsulfoxide (DMSO) as cryoprotective agent were studied in normal volunteers and thrombocytopenic patients. Use of 5 per cent DMSO and a freezing rate of 1-3 degrees C/minute yielded optimal preservation of platelet viability. The addition of 5 per cent Dextrose did not improve results. In vivo yield using 5 per cent DMSO was superior to previous results in which glycerol was used as the cryoprotective agent. Viability after freezing was equivalent when platelets were frozen in small (10 ml) and large (60 ml) volumes of plasma. The larger volume had the advantage that a smaller percentage of the platelets was lost during transfer from one plastic container to another.