Effect of Photobiomodulation on Structure and Function of Extracellular Vesicle Secreted from Mesenchymal Stem Cells.

The current study intended to evaluate the effect of photobiomodulation on the morphology and function of EVs secreted from mesenchymal stem cells (MSCs) derived from periodontal ligament (PDL) and the adipose tissue (ADSCs) (from buccal fat pad) in vitro. These cells were irradiated at 660 nm or kept in dark as control. EVs were then isolated from each group using ultracentrifugation. EVs were defined by flow cytometry and Western blot. Electron microscopy (SEM) was used to study the morphology of EVs. Then, MTT and wound-healing scratch assays were applied to compare the cell survival and migration of human dermal fibroblast (HDF) cells treated with the EVs obtained from the four groups. According to SEM images, isolated EV were round and cup-shaped in all groups showing no destructive effects of laser irradiation on EV morphology. MTT test results revealed a statistically significant difference between the HDF cells treated with different EV groups from hPDLSCs-Dark in comparison with control (0 μg/mL) (P < 0.05) and treated with exosome from hPDLSCs-Irradiation cells compared with dark group (P < 0.05). However, scratch wound-healing assay did not show a significant difference between various groups (P ˃ 0.05). Further studies with different irradiation protocols are recommended to find an optimal strategy.