(P-CB-29) The Quality and Functional Properties of Amotosalen-UVA-Treated Buffy-Coat Platelet Concentrates Are Better Preserved in PAS-E Additive Solution as Compared to PAS-C for 7-day Storage at +22°C

Background/Case Studies: Deterioration in the quality of platelet concentrates (PCs) during storage may be influenced by the methods used for their preparation and pathogen inactivation, the duration of storage and the type of platelet additive solutions (PAS). We evaluated the in vitro quality of buffy-coat (BC)-PCs treated with amotosalen-UVA (INTERCEPT Blood System, Cerus) and stored up to 7 days in two additive solutions, PAS-C (InterSol/PAS-III, Fresenius) or PAS-E (SSP⁺, Macopharma), a modification of PAS-C containing 5 mM KCl and 1.5 mM MgCl₂.

Study

Design/Methods: A pool-and-split strategy was used to obtain double-dose BC-PCs collected into PAS-C/plasma or PAS-E/plasma (55/45%) treated with amotosalen-UVA and stored at +22°C with constant agitation. The in vitro quality and function of PCs were tested over 7 days, including thrombus formation under flow at 1500 s^-1. Platelet subpopulations were identified using a combination of markers (P-selectin and phosphatidylserine (PhtdSer) exposure, DYm, PAC-1 binding for activated GPIIbIIIa) analyzed by multicolor flow cytometry. Statistical comparisons were done by two-way ANOVA followed by Tukey’s post-hoc test (n=4-7).

Results/Findings: Platelet counts were conserved in both types of PCs during storage, while mean platelet volume was significantly increased in PAS-C as compared to PAS-E, as of day (D) 3 (D7 p< 0.001). Storage in PAS-E resulted in a significant reduction in glucose consumption and lactate generation as compared to PAS-C with better maintenance of pH levels during late storage (p< 0.001). Notably, sufficient glucose was still available on D7 in PCs stored in PAS-E (2.3±0.4 mM). Spontaneous P-selectin exposure (α-granule secretion) was significantly increased in PCs stored in PAS-C as of D3 (D3 p=0.008; D7 p< 0.001), as was spontaneous PhtdSer exposure (platelet activation and apoptosis) during late storage of PCs in PAS-C (D7 p=0.002) unlike in PCs stored in PAS-E, suggesting that PAS may influence platelet activation state. Resting platelets dominated up to D7 in PAS-E (D3 82±3% vs. 58±5% p=0.006; D7 67±2% vs. 45±2% p< 0.001) replaced by activated platelets in PAS-C while procoagulant and apoptotic platelets emerged only in PAS-C at D7 (1±0% vs. 5±1% p=0.017 and 3±0% vs. 8±2% p=0.009 respectively). Lactate dehydrogenase (LDH) release (platelet lysis) was significantly reduced in PCs stored in PAS-E at D7 (p=0.008). Thrombus formation on collagen under flow with reconstituted hirudinated whole blood was better preserved at D7 in PAS-E (p< 0.01).

Conclusions: Use of PAS-E instead of PAS-C in INTERCEPT-treated BC-PCs improved platelet metabolism, reduced LDH release and reduced spontaneous activation. PAS-E preserved resting platelets without emergence of procoagulant and apoptotic platelet subpopulations, resulting in better maintained functional properties of thrombus formation under flow up to D7.