Impact of blue light irradiation on the viability of four types of human cells

Blue light therapies can be applied in treating various diseases, best represented by but limited to microbial infections. Since blue light can induce reactive oxygen species (ROS) in cells via various cellular pigments, it may have negative impact on normal human cells, while killing the target pathogens. This work aims at investigating this impact on the viability of four types of human cells, including those in lungs (represented by the A549 cell line), kidneys (represented by the 293T cell line), brain (represented by the SH-SY5Y cell line), and the immune system (represented by the THP-1 cell line). These cells were irradiated respectively by 450nm LED light sources, which is widely applied in both blue light therapies and optogenetics research. After the irradiation, the cell viability was tested by CCK-8 assay kits. The results showed significant reduction in the viability of 293T cells and SH-SY5Y cells. what’s more, with the increase of exposure time, the damage to the cells became more severe. We conclude that blue light may cause cell dysfunction through the action of ROS on DNA, and may contribute to cell death. Therefore, the dosage of 450nm blue light must be strictly controlled when used to treat diseases in kidney and brain.