Metabolomics evaluation of the photochemical impact of violet-blue light (405nm) on ex vivo platelet concentrates.

Abstract

Microbicidal violet-blue light in the visible spectrum (405nm) has been under evaluation for pathogen inactivation in ex vivo human plasma and platelets (PLTs) stored in plasma. Results to date have demonstrated that several blood-borne infectious disease-causing pathogens can be successfully reduced to significantly low levels in the light-treated plasma and PLTs. In order to evaluate whether the microbicidal 405nm light is safe for the treatment of PLT concentrates for pathogen inactivation, LC/MS-based metabolomics analyses were performed to evaluate the overall impact of 405nm violet-blue light treatment on ex vivo PLT concentrates suspended in plasma and on plasma itself, and to identify metabolome changes in intra-platelet and extra-cellular medium (i.e., plasma). The metabolomics data identified that platelet activating factors (PAFs), agonists and prostaglandins, which can influence PLT basic functions such as integrity, activation, and aggregation potential were unaltered, suggesting that 405nm light illumination is safe regarding PLT basic functions. Distinct increases in hydroxyl fatty acids and aldehydes, as well as decreases in antioxidant metabolites indicated that reactive oxygen species (ROS) were generated at high levels after only one hour of exposure to 405nm light. Distinctly changed endogenous photosensitizer metabolites after 1h of light exposure provided good evidence that 405nm light was an effective microbicide acting through ROS mechanism and no external additive photosensitizers were required.