Each of 15 healthy male volunteers was treated with 650 mg of aspirin 24 hours before the autologous transfusion of one unit of freeze-preserved platelets. Freeze-thaw-wash recovery values in vitro, viability and function in vivo, and the bleeding time and platelet aggregation response were measured. The platelets were frozen with 4 or 5 per cent dimethylsulfoxide (DMSO) at an overall rate of 2 to 3 C per minute and were stored at −80 C in a mechanical freezer for up to eight months. They were washed by dilution/centrifugation.

The mean recovery in vitro of platelets frozen with 4 per cent DMSO was 76 ± 16 per cent; the value was 64 ± 16 per cent for platelets frozen with 5 per cent DMSO. The mean in vivo 51Cr recovery of autologous platelets frozen with 4 per cent DMSO was 34 ± 6 per cent, and for platelets frozen with S per cent DMSO it was 33 ± 7 per cent. In both groups the platelet lifespan was normal. There was a significant reduction in bleeding time after the transfusion of a single unit of autologous platelets preserved with either 4 or 5 per cent DMSO, but no improvement in the aspirin-induced platelet aggregation pattern.