Light-emitting Diode Can Enhance the Metabolism and Paracrine Action of Mesenchymal Stem Cells

This study investigated the influence of red light-emitting diodes (LED, 630 nm) on different irradiation parameters and the number of applications on mesenchymal stem cells derived from adipose tissue (AdMSCs) metabolism and paracrine factors. The AdMSCs were irradiated with a LEDbox device (output power: 2452.5 mW; laser beam: 163.5 cm² ; irradiance: 15 mW cm^-2 ) using radiant exposures of 0.5, 2, and 4 J cm^-2 , respectively. AdMSCs were irradiated once or every 48 h up to three irradiations. All molecular analyses were performed 24 h after the last irradiation. LED did not induce changes in cell count, DNA damage, and oxidative stress. A significant repercussion of the LED has been noticed after three irradiations with 4 J cm^-2 . AdMSCs had higher levels of IL-6, IGF-1, and NOx index. A higher ATP content and MMT/Resazurin assay were identified in AdMSCs irradiated three times with 4 J cm^-2 . Mitochondrial basal respiration, maximal respiration and proton leak under metabolic stress were reduced by 0.5 and 2 J cm^-2 irradiations. These data showed that three LED irradiations with 4 J cm^-2 may be a suitable parameter for future AdMSCs therapy because of its improved metabolic activity, ATP content, and IL-6, IGF-1, and nitric oxide secretion.