HEMOSTATIC FUNCTION OF APHERESIS PLATELETS STORED AT 4°C AND 22°C

Introduction: Platelet refrigeration decreases the risk of bacterial contamination and may preserve function better than standard-of-care room temperature (RT) storage. Benefits could include lower transfusion-related complications, decreased costs, improved hemostasis in acutely bleeding patients, and extended shelf life. In this study, we compared the effects of 22 degrees C and 4 degrees C storage on the functional and activation status of apheresis platelets. Methods: Apheresis platelets (n = 5 per group) were stored for 5 days at 22 degrees C with agitation (RT) versus at 4 degrees C with agitation (4 degrees C + AG) and without (4 degrees C). Measurements included platelet counts, mean platelet volume, blood gas analytes, aggregation response, thromboelastography, thromboxane B-2 and soluble CD40 ligand release, activation markers, and microparticle formation. Results: Sample pH levels were within acceptable limits for storage products (pH 6.2-7.4). Platelet glucose metabolism (P < 0.05), aggregation response (adenosine diphosphate: RT 0; 4 degrees C + AG 5.0 +/- 0.8; 4 degrees C 5.6 +/- 0.9; P < 0.05), and clot strength (maximum amplitude: RT 58 +/- 2; 4 degrees C + AG 63 +/- 2; 4 degrees C 67 +/- 2; P < 0.05) were better preserved at 4 degrees C compared with RT storage. Refrigerated samples were more activated compared with RT (P < 0.05), although thromboxane B-2 (P < 0.05) and soluble CD40 ligand release (P < 0.05) were higher at RT. Agitation did not improve the quality of 4 degrees C-stored samples. Conclusions: Apheresis platelets stored at 4 degrees C maintain more viable metabolic characteristics, are hemostatically more effective, and release fewer proinflammatory mediators than apheresis platelets stored at RT over 5 days. Given the superior bacteriologic safety of refrigerated products, these data suggest that cold-stored platelets may improve outcomes for acutely bleeding patients.