Comparative Study on Photobiomodulation between 630 nm and 810 nm LED in Diabetic Wound Healing both in vitro and in vivo*

Photobiomodulation (PBM) promoting wound healing has been demonstrated by many studies. Currently, 630 nm and 810 nm light-emitting diodes (LEDs), as light sources, are frequently used in the treatment of diabetic foot ulcers (DFUs) in clinics. However, the dose-effect relationship of LED-mediated PBM is not fully understood. Furthermore, among the 630 nm and 810 nm LEDs, which one gets a better effect on accelerating the wound healing of diabetic ulcers is not clear. The aim of this study is to evaluate and compare the effects of 630 nm and 810 nm LED-mediated PBM in wound healing both in vitro and in vivo. Our results showed that both 630 nm and 810 nm LED irradiation significantly promoted the proliferation of mouse fibroblast cells (L929) at different light irradiances (1, 5, and 10mW/cm²). The cell proliferation rate increased with the extension of irradiation time (100, 200, and 500 s), but it decreased when the irradiation time was over 500 s. Both 630 nm and 810 nm LED irradiation (5mW/cm²) significantly improved the migration capability of L929 cells. No difference between 630 nm and 810 nm LED-mediated PBM in promoting cell proliferation and migration was detected. In vivo results presented that both 630 nm and 810 nm LED irradiation promoted the wound healing and the expression of the vascular endothelial growth factor (VEGF) and transforming growth factor (TGF) in the wounded skin of type 2 diabetic mice. Overall, these results suggested that LED-mediated PBM promotes wound healing of diabetic mice through promoting fibroblast cell proliferation, migration, and the expression of growth factors in the wounded skin. LEDs (630 nm and 810 nm) have a similar outcome in promoting wound healing of type 2 diabetic mice.