Reevaluation of the resting time period when preparing whole blood–derived platelet concentrates with the platelet‐rich plasma method

Abstract

The resting of platelet (PLT) pellets during the preparation of whole blood-derived PLT concentrates (PCs) is considered an essential step. A reevaluation of the rest period was conducted because preparation and storage conditions have been modified during the past 20 years. A two-site in vitro study (Study 1) was conducted with rest times of 0 to 5 minutes, 1 hour, and 4 hours (n = 31-33 per rest period). Leukoreduced PCs were stored for 5 days. A second study (Study 2) measuring in vivo viability was conducted at a third site (14 paired studies). PCs were prepared from 2 units of whole blood on the same day to simultaneously compare viability following storage and radioisotopic labeling. In Study 1, comparable in vitro parameters and swirling were observed with the three rest periods. The mean (+/-1 SD) values after storage for the extent of shape change and hypotonic stress parameters were 0 to 5 minutes, 16.7 +/- 7.2 and 66.0 +/- 15.7%; 1 hour, 19.1 +/- 6.9 and 69.3 +/- 17.9%; and 4 hours, 17.6 +/- 5.5 and 64.1 +/- 11.3%. In Study 2, the in vivo recovery was 49.9 +/- 15.3 and 50.9 +/- 20.2% with 0- to 5-minute and 1-hour rest periods, respectively. The corresponding survival time was 111.2 +/- 50.7 and 114.9 +/- 43.8 hours. These studies indicate comparable in vitro and in vivo viability properties with 0- to 5-minute and 1-hour rest periods and at 4 hours (in vitro only).