Effects of Narrow‐band IR ‐A and of Water‐Filtered Infrared A on Fibroblasts

Exposures of the skin with electromagnetic radiation of wavelengths between 670 nm and 1400 nm are often used as a general treatment to improve wound healing and reduce pain, for example, in chronic diabetic skin lesions. We investigated the effects of water‐filtered infrared A ( wIRA ) and of narrow‐band IR ‐A provided by a light‐emitting diode LED ( LED ‐ IR ‐A) irradiation in vitro on 3T3 fibroblast cultures under defined conditions with and without glyoxal administration. Glyoxal triggers the formation of advanced glycation end products, thereby mimicking a diabetic metabolic state. Cell viability and apoptotic changes were determined by flow cytometry after vital staining with Annexin V, YO ‐ PRO ‐1 and propidium iodide ( PI ), and by SubG1 assay. Mitochondrial function and oxidative stress were examined by vital staining for radical production, mitochondrial membrane potential ( MMP ) and the ratio of reduced‐to‐oxidized glutathione ( GSH / GSSG ). The metabolic state was monitored by a resazurin conversion assay. The numbers of apoptotic cells were reduced in cultures irradiated with wIRA or LED ‐ IR ‐A. More mitochondria showed a well‐polarized MMP after wIRA irradiation in glyoxal damaged cells. LED ‐ IR ‐A treatment specifically restored the GSH / GSSG ratio. The immediate positive effects of wIRA and LED ‐ IR ‐A observed in living cells, particularly on mitochondria, reflect the therapeutic benefits of wIRA and LED ‐ IR ‐A.