Impact of 450 nm blue light on platelet multiomics and bacterial inactivation

To investigate the efficiency of 450 nm blue light irradiation on bacterial inactivation in apheresis platelets and the effects of irradiation on the quality of apheresis platelets. The toxicity of 450 nm blue light on the Staphylococcus aureus (S. aureus) (10² CFU/ml). The bacterial cells were incubated with different time of 29 mW/cm² intensity 450 nm blue light (0, 0.5, 1, 2, 3, 4 h). Viable bacteria counts and platelet indices (platelet count, MPV, PDW, MA, PF) were measured pre- and post-irradiation. Proteomics and metabolomics analyses assessed changes in platelets and the impact of blue light. The numbers of viable bacteria in platelet decreased significantly after irradiation (P < 0.05). No significant difference was detected in the physicochemical indexes of platelet (platelet counts, MPV, PDW, MA, PF) between the control group and the treated group (after irradiation) (P > 0.05). Our platelet metabolomics analysis revealed alterations in 34 out of 981 quantified metabolites (3.5%). Additionally, we identified a total of 3726 proteins, and through comparative screening between two groups, we identified 71 differentially expressed proteins (1.9%), comprising 43 upregulated and 28 downregulated proteins. These findings suggest that a minimal number of proteins and metabolites exhibited changes in expression in the light-treated platelets compared to the untreated controls. The 450 nm blue light of a certain intensity irradiation could sufficiently kill S. aureus, but had no significant effect on the quality of apheresis platelets. This research has provided further evidence supporting the potential for 450 nm blue light to be developed as a pathogen reduction tool for stored platelets.