Impact of Pathogen Reduction Technology Treatment and Storage in New Generation Platelet Additive Solutions (PAS) on Platelet Function.

Abstract 2115

Poster Board II-92

New strategies for preparing platelet concentrates (PCs) are investigating the combination of pathogen reduction technologies (PRT) with storage of platelets in additive solutions (PAS) containing phosphate buffer. While these approaches have several advantages by reducing adverse effects, improving biological safety and increasing plasma availability, there is a reasonable concern on how these strategies could affect platelet function. In the present study we have evaluated the effect of Marisol^® PRT treatment (CaridianBCT Biotechnologies, LLC) in combination with storage in PAS-III (Intersol; Baxter Healthcare Corp) or PAS-IIIM (SSP+; MacoPharma) on analytical and functional characteristics of apheresis PCS.

PCs (2.5-3.4×10⁹plts/ml) were split into three aliquots. One was kept untreated and stored in plasma as a control (CON-PPP). One was PRT-treated and stored in the corresponding PAS (PRT-PASIII or PRT-IIIM) with a 35% plasma carryover to achieve a final concentration of 0.7-1.5 × 10⁹ plt/ml. The last aliquot was stored in the corresponding PAS (CON-PASIII or CON-PASIIIM), not subjected to PRT treatment. PCs were stored under standardized conditions and evaluations were performed on days 0, 5 and 7. Cell quality parameters (pH, swirl, lactate and glucose), flow cytometry analysis of major platelet glycoproteins and activation dependent antigens were assessed. Adhesive and aggregating functions of platelets were evaluated using an ex vivo perfusion model with flowing reconstituted blood recirculating through damaged vascular segments.

A slight reduction in platelet counts was noticed on day 7 compared to day 0 in PRT-treated PCs (p<0.05), however no statistical differences were observed between the different study groups. All measured cell quality parameters were within ranges previously published. Flow cytometry analysis revealed comparable levels of the analyzed glycoproteins for all conditions evaluated. Only moderate reductions in the expression of GPIb were observed on day 7 of storage in all groups except for CON-PASIIIM. A progressive increase in the expression of P-selectin was observed in both controls and PRT-treated PCs during storage. Lysosomal integral membrane protein (LIMP) expression was increased in PRT-PASIII and PRT-PASIIIM and CON-PASIII, but not CON-PASIIIM PCs. PRT-PASIII PCs showed the highest levels of annexin V binding after 7 days of storage. Studies under flow conditions showed comparable levels of adhesion and aggregation to subendothelium for PRT-treated platelets stored in PAS solutions at 5 days of storage. A detailed morphometric analysis revealed slightly enhanced adhesive functions in CON-PASIII on day 0 and moderate reductions in adhesive properties in PRT-PASIII, but not PRT-PASIIIM PCs after 7 days of storage.

Our investigations show that cell quality parameters, glycoproteins levels and platelet functions were preserved in PRT-treated concentrates and stored in new generation PAS for up to 5 days. The relevance of our experimental data on the in vivo performance of PCs exposed to PRT and stored in new generation PAS deserve further investigation in the clinical setting.