Photochemical inactivation of selected viruses and bacteria in platelet concentrates using riboflavin and light

BACKGROUND: A medical device is being developed for the reduction of pathogens in PLT concentrates (PCs). The device uses broadband UV light and the compound riboflavin (vitamin B-2). STUDY DESIGN AND METHODS: Pathogens were added to single-donor PLTs. After treatment, the infectivity of each pathogen was measured using established biologic assays. In vitro PLT performance was evaluated after treatment and after 5 days of storage using a panel of 10 in-vitro cell quality assays. RESULTS: In studies with viral pathogens, the Pathogen Reduction Technology (PRT) system provided average log reduction factors of 4.46 +/- 0.39 for intracellular HIV, 5.93 +/- 0.20 for cells associated HIV, and 5.19 +/- 0.50 for West Nile virus. For the nonenveloped porcine parvovirus, a reduction factor greater than 5.0 log was observed. Staphylococcus epidermidis and Escherichia coli bacteria were also tested with observed reduction factors to the limits of detection of 4.0 log or greater. PLT cell quality was adequately maintained after treatment and during storage. Although P-selectin expression, glucose consumption, and lactate production increased relative to controls, this was not beyond accepted levels. The pH of treated PCs also decreased slightly relative to control PLTs on Days 1 and 5. CONCLUSION: The data indicate that the device successfully reduced the number of selected pathogens in PCs. Despite the fact that significant differences exist between treated and control in-vitro variables, it is speculated that the clinical effectiveness of both products will not be significantly different, based on comparison to historical data for products in routine clinical use today.