Associate Member Bloodworks Northwest Seattle, Washington, United States
Background/Case Studies: Platelet transfusions are critical for bleeding patients or patients at risk of bleeding. For this purpose, platelets are stored at room temperature or cold (1-6 °C). Cold-stored platelets (CSPs) have a longer shelf life, can reduce bacterial contamination, and may be more or equally effective compared to room temperature-stored platelets (RTPs). However, CSPs can form aggregates, ultimately making them unusable. What causes these aggregates and how to prevent them is poorly understood. This study aims to identify potential donor factors related to aggregate formation in CSPs.
Study
Design/Methods: We obtained 79 CSP units manufactured in plasma from unique donors during a clinical trial. All units were shipped from South Texas Blood and Tissue Center, TX, to Swedish Medical Center in Seattle, WA. We analyzed the aggregate rates among donors of different sexes, ages, and blood groups. We also tracked the time at the blood center and at the transfusion service lab (TSL) in the hospital. The same criteria to define aggregates in RTPs were applied to CSPs. In a subgroup of CSP samples (n=12) with and without aggregates, we performed ELISA testing for plasma proteins known to be involved in thromboinflammation.
Results/Findings: Forty-five (57%) units developed aggregates, and 34 (43%) did not. Most donors were blood type A, RhD-positive, followed by O, RhD-positive. As expected, RhD-negative donors were much less frequent. The ABO and RhD blood types did not differ significantly in their likelihood of developing aggregates, however, a trend was observed for fewer units with aggregates of blood type O (p=0.078). Overall, more donors were male than female. Platelets from female donors were significantly more likely to develop aggregates than those from male donors (p=0.035). The donor age ranged from 17 to 85 years and was not significantly different between units with and without aggregates (p=0.15). The time between collection and shipment (blood center time) and between receipt of platelets and transfusion (transfusion service lab time) did not differ significantly between units with and without aggregates. Units with aggregates had higher levels of VWF approaching significance (p=0.057), and significantly lower soluble thrombomodulin levels (p=0.002). We observed no significant difference between aggregated and non-aggregated units for sphingosine-1-phosphate, fibrinogen, vascular endothelial growth factor, and soluble CD40.
Conclusions: Female sex and lower thrombomodulin levels were significant predictors of aggregates in CSP. Blood group A and higher VWF levels were approaching significance, but whether there is a true difference needs to be confirmed in larger cohorts. Consistently, ABO types have previously been shown to influence VWF levels. Our findings are a first step toward better understanding CSP aggregates.
