Cytotoxic Effects of 405 nm and 470 nm Blue Light on Mammalian Cells and Blood Components: A Literature Review

This literature review evaluates the cytotoxic effects of 405 nm and 470 nm blue light on mammalian cells and blood components, synthesizing dose‑dependent thresholds across major assays including MTT, LDH, ROS, bioenergetics, and morphological analyses. Drawing from fibroblast, osteoblast, monocyte, platelet, red blood cell, and retinal pigment epithelial studies, the review compares how porphyrin‑ and flavin‑driven photochemical pathways generate reactive oxygen species and how these mechanisms translate into measurable cellular damage at different fluences. Across the surveyed evidence, 405 nm light demonstrates a clear therapeutic window, with multiple studies reporting no significant viability loss between 3.6–36 J/cm², while cytotoxicity emerges consistently at or above ~54 J/cm². In contrast, 470 nm light shows cell‑type‑specific responses, with fibroblasts tolerating up to 55–110 J/cm², immune cells showing minimal sensitivity, and retinal pigment epithelial cells exhibiting oxidative stress at doses as low as 1 J/cm². Blood components behave differently from mammalian tissue: red blood cells respond through a calcium‑dependent mechanism unrelated to porphyrin excitation, and platelets show mitochondrial impairment only at very high doses (>216–270 J/cm²). The review identifies a major gap in the literature: no existing studies test unseparated whole blood at either wavelength, making current evidence insufficient for predicting real‑world wound‑level responses. The paper concludes by recommending that BlueAid Innovations conduct direct whole‑blood testing using standardized MTT, LDH, and ROS assays to establish safe and effective dosing thresholds for future antimicrobial photomedicine devices.