In Vitro Biochemical And Functional Comparison Of Amotosalen-UVA-Treated Buffy-Coat Platelet Concentrates Stored In Pas-C Or Pas-E Additive Solution Up To 7 Days

¹INSERM UMR-S1255, ²Etablissement Français du Sang-Grand Est, Strasbourg, France

Background: Deterioration in the quality of platelet concentrates (PCs) during storage results from changes of various biochemical and metabolic parameters affecting platelet haemostatic properties and survival after transfusion. These lesions depend on the methods used for preparation and pathogen inactivation, the duration of storage and the type of platelet additive solutions (PAS) used. However, there exists no detailed comparison of PAS-C (InterSol/PAS-III, Fresenius) and PAS-E (SSP⁺, Macopharma), a modification of PAS-C containing 5 mM KCl and 1.5 mM MgCl₂, for the conservation of buffy-coat (BC)-PCs treated with amotosalen-UVA (INTERCEPT Blood System, Cerus) with regard to the storage changes including in vitro platelet functional properties.

Aims: We evaluated the in vitro quality of BC-PCs treated with INTERCEPT and stored up to 7 days in either PAS-C or PAS-E.

Methods: A pool-and-split strategy was used to obtain two study groups (n = 5 per group): (i) double-dose BC-PCs collected into PAS-C/plasma (55/45) treated with amotosalen-UVA, (ii) double-dose BC-PCs collected into PAS-E/plasma (55/45) treated with amotosalen-UVA. The in vitro quality and function of the platelet components were tested over 7 days of storage post collection at 22–24°C.

Results: Platelet counts were conserved in both groups of PCs during storage, as was platelet swirling without the appearance of macroscopic aggregates. Storage in PAS-C resulted in a significant increase in mean platelet volume (MPV) as of day 3, as compared to storage in PAS-E, where it remained stable. Integrin αIIbβ3 and glycoprotein (GP) VI expression remained stable in both solutions, whereas GPIbα and GPV declined similarly in both groups. Storage in PAS-E resulted in a significant reduction in glucose consumption and lactate generation as compared to storage in PAS-C on day 5.5, with better maintenance of pH levels as of day 3. Notably, sufficient glucose was still available on day 7 in PCs stored in PAS-E compared to PCs stored in PAS-C. Spontaneous P-selectin exposure, a marker of α-granule secretion, was significantly reduced in PCs stored in PAS-E as compared to PAS-C as of day 1.5. The proportion of activated αIIbβ3 remained globally low and similar in both study groups. Spontaneous phosphatidylserine (PS) exposure at the surface of platelets, a marker for platelet activation and apoptosis evaluated by annexin V binding, significantly increased during late storage of PCs in PAS-C compared to PCs conserved in PAS-E where it remained stable. Mitochondrial transmembrane potential, evaluated using the tetramethylrhodamine methyl ester (TMRM) fluorescent dye retained in functional intact mitochondria, diminished significantly in PCs stored in PAS-C but not in PAS-E as of day 5. Lactate dehydrogenase (LDH) release, an indication of premature platelet lysis, was significantly reduced in PCs stored in PAS-E as compared to PAS-C, as of day 5.5. During storage, both PAS-C and PAS-E platelets retained capacity to adhere to VWF and fibrinogen, and to form aggregates of similar thrombus volume on collagen in a microfluidic shear flow chamber.

Summary/Conclusions: Use of PAS-E/plasma improved platelet metabolism, reduced spontaneous activation, reduced apoptosis and reduced LDH release, as compared to PAS-C/plasma, especially during the late stages of storage, without differences in in vitro platelet adhesive properties. This study highlights the strong influence of the composition of the additive solution on the occurrence of storage lesions in pathogen-reduced PCs.