Abstract
Background: The risk of bacterial growth has limited the shelf life of platelet concentrates (PC) to 5 days. Modern platelet storage containers facilitate storage for up to 7 days, if bacterial contamination is prevented. INTERCEPT (Baxter, La Chatre, France; Cerus, Concord, CA) photochemical treatment (PCT) for pathogen reduction based on amotosalen (150μM) and UVA illumination (3 J/cm2) inactivates high titers of bacteria in PC (Transfusion2004; 44: 1496–1504). Adhesion and aggregation of platelets to injured vascular surfaces are critical aspects of platelet hemostatic function. In this study, the adhesion and aggregation of leucocyte-reduced buffy coat derived PC (BCPC), treated with INTERCEPT and stored up to 7 days, were measured on injured vascular surfaces using an ex-vivo blood flow system.
Methods: BCPC were prepared from 450 mL-whole blood donations with the top and bottom method (Optipress II, Baxter). Five BCPC, of the same ABO group, were pooled with additive solution (Intersol™) the day following collection, after viral screening testing was completed. Following centrifugation and leukocyte depletion, two BCPC pools of the same ABO group were mixed and divided. One pooled BCPC was treated with INTERCEPT (I-BCPC) and the other was prepared by conventional methods (C-BCPC); and both were stored in 1.3 liter PL2410 plastic containers (Baxter R4R7012) at 22 ± 2°C with continuous agitation for 7 days. Samples for hemostatic function testing were taken immediately after preparation before splitting for treatment and after 5 and 7 days of storage. Platelet counts were performed in K3EDTA in a Coulter MD II counter (Coulter, Miami, FL). Samples of I-BCPC and C-BCPC were added to citrate anticoagulated blood, previously depleted of platelets and leukocytes by filtration, and adjusted to a final platelet count of 150x109/L. Enzymatically denuded vascular segments were exposed to circulating whole blood, reconstituted with I-BCPC and C-BCPC, in Baumgartner chambers at a shear rate of 800 s−1 for 10 minutes. The proportion (%) of the vascular surface area covered by platelets after perfusion was measured for each type of BCPC (N = 9) at each storage time point. Platelets and groups of platelets were classified as adhesive when platelet masses were less than 5 μm in height and as thrombi when height exceeded 5 μm. Data were analyzed with the SPSS 12.0.1 statistical package with significance at p < 0.05, and expressed at the mean ± SEM Results(Table).
Conclusion: The platelet count of I- BCPC decreased by 12.3% including PCT processing losses and 7 days of storage. However, I- BCPC platelet adhesive and aggregatory capacities under flow conditions were similar to C- BCPC, and were well conserved for up to 7 days of storage.
Hemostatic Function of Stored I-BCPC and C-BCPC Parameter I-BCPC C-BCPC p Day 1(Pre Treatment) Platelet Count (109/L) 945±40 945±40 Platelet Coverage (%) 26.0±3.7 26.0±4.2 Adhesion(%) 24.0±3.7 24.0±3.7 Thrombus(%) 1.9±0.6 1.9±0.6 Day 5 Storage Platelet Count (109/L 844±41 902±44 0.004 Platelet Coverage (%) 20.9±2.2 20.6±1.6 0.9 Adhesion(%) 19.9±2.1 19.3±1.4 0.8 Thrombus(%) 0.9±0.3 1.2±0.4 0.5 Day 7 Storage Platelet Count (109/L) 829±32 923±48 0.008 Platelet Coverage (%) 27.1±2.9 21.2±2.8 0.06 Adhesion(%) 26.0±2.7 20.4±2.7 0.06 Thrombus(%) 1.2±0.3 0.7±0.2 0.16
The Increased Effectiveness of Platelet Concentrates Prepared in Acidified Plasma