In vitro thrombus formation and in vivo hemostasis mediated by platelets irradiated with bactericidal ultraviolet C from xenon flash under flow conditions.

BACKGROUND: We previously reported a flow path-ultraviolet C (UVC) irradiation system for platelet concentrates (PCs) with platelet additive solution (PAS) to minimize contamination by bacteria. Here, we investigated functionalities of irradiated platelets (PLTs) in in vitro thrombus formation and in vivo hemostasis. STUDY DESIGN AND METHODS: PAS-PCs were irradiated with flash UVC using the flow path system. Their variables (PLT count, mean platelet volume, pH, glucose, lactate, glycoprotein [GP] Ib, and activated integrin αIIbß3) were evaluated. Static adhesion to collagen or fibrinogen was analyzed using fluorescent microscopy. Thrombus formation under flow conditions was assessed using a collagen-coated bead column. Adenosine diphosphate (ADP)-induced Akt phosphorylation was determined by western blot. In vivo hemostasis and circulatory survival of PLTs were assessed with a rabbit bleeding model. RESULTS: All variables, except for GPIb expression, were slightly, but significantly, impaired after flash UVC irradiation throughout the 6-day storage period. No difference was observed in static adhesion to either collagen or fibrinogen between irradiated and nonirradiated PAS-PCs. In vitro thrombus formation of flash UVC-irradiated PAS-PCs was significantly greater than that of nonirradiated PAS-PCs. ADP-induced Akt phosphorylation was enhanced in irradiated PAS-PCs. In vivo hemostatic efficacy was comparable between the groups on Day 1. The efficacy declined in nonirradiated PAS-PCs on Day 5, while it was retained in flash UVC-irradiated PAS-PCs. Circulatory survival of PLTs was lower in irradiated PAS-PCs. CONCLUSIONS: PAS-PCs irradiated with UVC from xenon flash have favorable properties to achieve hemostasis compared with nonirradiated PAS-PCs.

In vitro effects on platelets irradiated with short-wave ultraviolet light without any additional photoactive reagent using the THERAFLEX UV-Platelets method.

BACKGROUND: A novel short-wave ultraviolet light (UVC) pathogen reduction technology (THERAFLEX UV-Platelets; MacoPharma, Mouvaux, France) without the need of any additional photoactive reagent has recently been evaluated for various bacteria and virus infectivity assays. The use of UVC alone has on the one hand been shown to reduce pathogens but may, on the other hand, have some impact on the platelet (PLT) quality. The purpose of this study was to determine the potential effects on PLT quality of pathogen inactivation treatment using the novel UVC method for PLT concentrates. STUDY DESIGN AND METHODS: Buffy-coat-derived PLTs suspended in SSP+ were irradiated with UVC light in plastic bags (MacoPharma) made of ethyl vinyl acetate, considered to be highly permeable to UVC light. The UVC-treated (test, n=8) as well as the untreated (reference, n=8) PLT units were stored in PLT storage bags composed of n-butyryl, tri n-hexyl citrate-plasticized polyvinyl chloride (MacoPharma) on a flat bed agitator for in vitro testing during 7 days of storage. RESULTS: No significant difference in PLT counts and lactate dehydrogenase between the groups was detected. During storage, glucose decreased more and lactate increased more in the test units. Statistically significant differences were found for glucose (P<0·01) and lactate (P<0·05) on day 7. ATP levels were higher (P<0·01 from day 5) in the reference units. With exception of day 7 (P<0·01 reference vs. test), hypotonic shock response reactivity was not different between groups. Extent of shape change was lower (P<0·01), and CD62P (P<0·05 day 5) was higher in the test units. CD42b and CD41/61 showed similar trends throughout storage, without any significant difference between the units. pH was maintained at >6·8 (day 7) and swirling remained at the highest level (score = 2) for all units throughout storage. CONCLUSION: Our results suggest that irradiation with UVC light has a slight impact on PLT in vitro quality and appears to be insignificant with regard to current in vitro standards.

Effects of a new pathogen-reduction technology (Mirasol PRT) on functional aspects of platelet concentrates.

BACKGROUND: Several strategies are being developed to reduce the risk of pathogen transmission associated with platelet (PLT) transfusion. STUDY DESIGN AND METHODS: The impact of a new technology for pathogen reduction based on riboflavin plus illumination (Mirasol PRT, Navigant Biotechnologies, Inc.) at 6.2 and 12.3 J per mL on functional and biochemical characteristics of PLTs was evaluated. PLT concentrates (PCs) obtained by apheresis were treated with Mirasol PRT and stored at 22 degrees C. Modifications in major PLT glycoproteins (GPIbalpha, GPIV, and GPIIb-IIIa), adhesive ligands (von Willebrand factor [VWF], fibrinogen [Fg], and fibronectin), activation antigens (P-selectin and LIMP), and apoptotic markers (annexin V binding and factor [F]Va) were analyzed by flow cytometry. Adhesive and cohesive PLT functions were evaluated with well-established perfusion models. Studies were performed on the preparation day (Day 0) and during PCs storage (Days 3 and 5). RESULTS: Levels of glycoproteins remained stable during storage in PCs treated with 6.2 J per mL pathogen reduction technology (PRT) and similar to those observed in nontreated PCs. When 12.3 J per mL PRT was applied, however, levels of GPIbalpha moderately decreased on Days 3 and 5. VWF, Fg, and FVa were not modified in their expression levels, either by treatment or by storage period. Fibronectin appeared more elevated in all PRT samples. A progressive increase in P-selectin and LIMP expression and in annexin V binding was observed during storage of PRT-treated PCs. Functional studies indicated that 6.2 J per mL Mirasol PRT-treated PLTs preserved adhesive and cohesive functions to levels compatible with those observed in the respective control PCs. CONCLUSION: PLT function was well preserved in PCs treated with 6.2 J per mL Mirasol PRT and stored for 5 days.