Evaluation of in vitro storage properties of prestorage pooled whole blood-derived platelets suspended in 100 percent plasma and treated with amotosalen and long-wavelength ultraviolet light.

Amotosalen, a psoralen, has been utilized for photochemical treatment (PCT) of apheresis platelets (PLTs) and pooled buffy coat PLTs suspended in additive solution. In the United States, the source of many PLT transfusions is from whole blood-derived PLTs prepared by the PLT-rich plasma (PRP) method. This study investigated the in vitro PLT properties of amotosalen-PCT of leukoreduced pools of PLTs prepared by the PRP method and suspended in 100 percent plasma. On Day 1 of storage, 12 leukoreduced (n = 6) or 10 leukoreplete (n = 6) ABO-identical PLT concentrates were pooled, separated into two pools of 6 or 5 units, respectively, and leukoreduced (leukoreplete pools only). Each pool of 5 or 6 units was then photochemically treated (designated "test": amotosalen plus 3.0 J/cm(2) long-wavelength ultraviolet light followed by amotosalen/photoproduct removal) while the remaining identical pool (designated "control") was untreated. PLT in vitro assays were performed on test and control pools during 7-day storage. PCT resulted in slightly reduced pH in test pools compared to that of matched control pools after 5 days of storage (5-unit pools: test, 6.96 +/- 0.12 vs. control, 7.15 +/- 0.09, p = 0.0033; 6-unit pools: test, 6.90 +/- 0.10 vs. control, 7.07 +/- 0.09, p < 0.0001). Test pools adequately maintained many other in vitro properties including PLT morphology, hypotonic shock response, and extent of shape change parameters during 5-day storage, which, like pH, also differed from those of controls. The pH of test and control pools declined on Day 7, with 1 of 6 test pools (either 5 or 6 units) having a pH value of less than 6.20, while all control pools had pH values of more than 6.66. PCT of leukoreduced PLT pools of whole blood-derived PLTs in 100 percent plasma maintained adequate PLT in vitro variables through 5 days of storage.