Abstract Body: Aspirin (ASA) irreversibly inhibits platelet cyclooxygenase-1, impairing thromboxane A2 synthesis and reducing platelet aggregation. Platelet (PLT) transfusion can be used to restore function, yet the impact of cold storage (CS) on transfusion efficacy in this context in bleeding patients and other disease etiologies remains unclear. There is a lack of preclinical human models for high-throughput developmental research.

We hypothesized that PLT transfusion would restore function in ASA-treated blood and CS-PLTs would have equivalent efficacy to Day 0 PLTs in a high throughput in vitro model.

This exploratory in vitro study assessed PLT function before and after simulated PLT transfusion in ASA (125 μM)-treated whole blood using two assays: TEG 6s platelet mapping (PM) and Impedance Aggregometry (IA). For TEG (n=5), fresh (Day 0, n=2) or CS PLTs (≤Day 14, n=3) were mixed at 20% of whole blood volume. For IA (n=4), CS PLTs (≤21 days, n=4) were tested at 30% and 40%, maintaining constant hematocrit with autologous RBCs. A paired t-test and repeated-measures ANOVA were used for statistical analysis.

ASA induced 94 ± 4.2% inhibition of arachidonic acid (AA) response on TEG in vitro. PLT mixing significantly restored Maximum Amplitude (MA) from 14.5 ± 4.4 to 48.2± 20.7 (p = 0.01) (Figure 1). CS PLTs on Day 6 (n = 2) had the highest recovery (MA = 65.5 ± 0.5) compared to fresh PLTs at Day 0 (n = 2, MA = 26.9 ± 11.7). Day 14 (n=1) also reversed dysfunction (MA = 56.2). CS PLT mixing however did not change PLT count (227.0 ± 90.0 vs. 221.0 ± 81.0 pre-mixing), confirming platelet activity recovery rather than a numerical increase. IA (Figure 2) showed that 40% CS PLT (≤21 days, n=4) mixing increased function with no significant difference from baseline. (AA Max 4.5 ± 2.4 vs. 7.8 ± 1.7). Similarly, 30% PLT transfusion showed partial recovery, while 20% resulted in limited recovery. PLT counts trended upward but without statistically significant differences across conditions.

PLT transfusion in vitro effectively restores PLT function following ASA-induced inhibition, supporting its role as rapid strategy for urgent reversal. CS PLTs show strong efficacy, reinforcing their clinical viability in transfusion protocols. Further research with a larger sample size and additional assays is needed to comprehensively assess their efficacy, though our preliminary data support feasibility of this model to be used in future research to refine approaches and develop novel strategies.