Influence of a 12‐hour, 22°C holding period for buffy coats on the preparation of platelet concentrates stored in plasma

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Abstract
The preparation of platelet concentrates (PCs) from buffy coats (BCs) stored at room temperature is controversial, because of the strong metabolic activity of cells in BCs and the possible detrimental effect of neutrophil enzymes on platelets when the holding time before separation is prolonged. Despite good in vitro and in vivo behavior of BC-PCs stored in synthetic solution, little is known of the quality of BC-PCs stored in plasma. Comparison was made of PCs prepared from BCs held at 22 degrees C for 3 hours (3-hour BC-PCs) or overnight (12-hour BC-PCs) and stored in plasma. Platelet and white cell counts, pH, response to osmotic shock, and morphologic scores were determined on 20 PCs of each type. The decrease in dense granule and alpha granule content, a marker of platelet activation, were estimated by mepacrine counting and beta-thromboglobulin measurement, respectively (n = 8-10). Platelet function was studied in terms of aggregation and thromboxane production in response to various concentrations of collagen and thrombin (n = 8-17). PCs prepared from unstored BCs (n = 15) and from BCs held for 90 minutes (n = 15) were used as controls. Platelet yield was increased from 53 +/- 10 percent of donated platelets to 73 +/- 4 percent by increasing the BC holding time from 0 to 90 minutes to 3 hours (p < 0.001). Similar yields (7.8 +/- 1.8 vs. 7.9 +/- 2 x 10(10) platelets) and white cell contamination (0.9 +/- 0.8 vs. 1.0 +/- 0.9 x 10(7)) were obtained with 3-hour and 12-hour BC-PCs. At the end of the storage period (Day 5), all variables known to correlate with platelet survival in vivo were well maintained in both 3-hour and 12-hour BC-PCs: pH > or = 6.9, response to osmotic shock > or = 70 percent, and morphology scores always > or = 240. During storage, the dense granule content decreased moderately (30% after 5 days), whatever the conditions. By contrast, the total platelet beta-thromboglobulin content was better preserved in 12-hour BC-PCs than in 3-hour BC-PCs (p < 0.04). No significant differences were observed in collagen-induced aggregation and thromboxane production in the two PC preparations. However, aggregation responses to thrombin were higher in 12-hour BC-PCs on Day 5 of storage (p < 0.01). BCs can be held at 22 degrees C for up to 12 hours, with no detrimental effect on the quality of PCs stored for up to 5 days in plasma. Such a holding time might help overcome logistic problems in blood banks.