FIGURE 3.

Depict of time lines of antimicrobial blue light (aBL) irradiation (A) and evaluation of its effects on platelets (PLTs) (B). A, The 2-day-old human PLT concentrates were irradiated with sham or 405 nm aBL once during storage or once a day for three consecutive days (from day 3 to day 5 after PLT collection) (blue triangle). The light-emitting diode (LED) was held firmly by a clamp on a support stand, and the distance between the LED and the PLT storage bag was fixed to obtain 55 mW/cm² for the experiments (inset photo). The PLTs were irradiated at indicated times controlled by a LED controller while gently shaking on the shaker at 60 to 70 rpm. Residual bacteria in the PLT concentrates were determined on day 5 after aBL irradiation (day 7 after PLT collection). PLTs were counted to determine viability in 2 hours (day 2 after PLT collection), 2 days (day 4 after PLT collection) and 5 days (day 7 after PLT collection) after sham or aBL irradiation (red). PLT activations were analyzed in 2 hours (day 2 after PLT collection), 2 days (day 4 after PLT collection) and 3 days (day 5 after PLT collection) after sham or aBL irradiation (purple). PLT aggregations were assayed in 2 hours (day 2 after PLT collection) and 2 days (day 4 after PLT collection) (green). B, Bacillus cereus ATCC 14579, Staphylococcus epidermidis ATCC 35985, Streptococcus pyogenes, USA 300, Pseudomonas aeruginosa ATCC 19660 or Candida albicans CEC 749 was cultured overnight and added to PLT storage bags at 100 CFU/bag containing 3 mL PLT concentrates supplemented with 65% PLT additive solution (PAS). The bags each were exposed to sham light (●) or 405 nm aBL at 25 (■), 50 (▲) or 75 (▼) J/cm² and then stored in a standard condition for 5 days. The number of residual bacteria in each bag was determined on day 5 after irradiation as Figure 2, n = 8. *P < .05, **P < .01 and ****P < .0001 in the presence or absence of aBL. ns, no significance