Storage Characteristics of Split Double-Dose Platelet Concentrates Derived from Apheresis and Treated with Amotosalen Hydrochloride and UVA Light for Pathogen Inactivation

Background: By inhibiting nucleic acids, photochemical treatment (PCT) using amotosalen hydrochloride (S-59) in combination with UVA light provides a new method for the inactivation of pathogens and leukocytes, potential contaminants of platelet concentrates (PCs). Material and Methods: We evaluated the effect of PCT on function and viability of PCs derived from apheresis over a storage period of 5 days. Double-dose PCs containing 6.5–7.0 × 10 11 platelets (n = 8) were collected in 600 ml of approximately 35% autologous plasma and 65% platelet additive solution. Each collection was split into two equal-sized portions for paired analysis. One day after collection, test PCs were mixed with 15 ml of 3 mmol/l S-59 and illuminated with UVA light for 3 min, followed by a 6- to 8-hour incubation in a compound adsorption device (CAD) for the reduction of residual S-59 and unbound photoproducts. In vitro platelet function measurements included platelet count, pH, lactate dehydrogenase (LDH), β-thromboglobulin (β-TG), hypotonic shock response (HSR), extent of shape change (ESC) and the expression of p-selectin. Platelet morphology and ultrastructure were analyzed by light and electron microscopy (EM). Results: We found no statistically significant differences on day 5 of the storage between the control and test platelets for pH, platelet count, p-selectin, ESC, HSR, morphology, and the percentage of lysed platelets analyzed by EM. The level of β-TG was reduced in the test units by the CAD step. Significant differences (p < 0.05) were observed for LDH and HSR immediately after PCT, indicating a slight platelet activation. Until the end of the storage period, LDH increased further in control and test platelets, but the quantitative difference between both products did not vary upon further storage. The effect for HSR was transient as no differences between treated and untreated PCs were detected at the end of the storage period. Conclusion: These in vitro results indicate that PCT with amotosalen and UVA light is applicable for split double-dose platelets derived from apheresis as it leads only to a transient activation of platelets immediately after the procedure, without affecting the function and structure of PCs over the 5-day storage period.