Type of Agitation and Platelet Viability and Function After 22°C Storage: Correlation with Maintenance of Discoid Shape

Abstract

Platelet viability as measured by in vivo 51cr recovery, platelet morphology, and in vitro aggregation with ADP and thrombin were studied with platelet concentrates (PC) stored for transfusion under carefully controlled conditions. The PC were prepared from whole blood with citrate-dextrose-phosphate as anticoagulant. The platelet count was kept between 0.8 − 1.6 × 106 platelets per mm3 in a volume of 50 ml. The PC were stored in containers constructed of polyethylene (PE) or Polyvinylchloride (PVC) at 22°C for 72 hours. The bags were placed on a horizontal shaker or a ferris wheel type of apparatus during storage. No significant changes in pH or platelet count were observed during storage. PC stored on the wheel showed a moderate loss of viability and marked loss of aggregation response compared to PC on the shaker. Under optimal conditions with PC in PE on the shaker maximal rate of aggregation was reduced only 26% compared to fresh PC. PC stored in PVC showed a statistically significant greater decrease. A good correlation was observed between the percentage of discoid platelets present in the PC as judged by phase microscopy and the extent of platelet shape change response to ADP. Both parameters correlated positively with in vivo 51Cr recovery. We conclude: 1) The type of agitation used significantly effects maintenance of platelet viability and function during storage. 2) Under the conditions used, in vitro function was better preserved in PE than in PVC bags. 3) In vitro function is not inevitably lost during storage at 22°C, but is critically dependent on storage conditions. 4) In vivo platelet viability (51Cr recovery) correlates with maintenance of disc shape. The latter can be quantitated by the shape change response with ADP.