FCP 4 : The effect of LED irradiation using 630 nm, 830 nm and combination of the two wavelengths on hair growth promotion in vitro and in vivo

Background: Light-emitting diodes (LED) are considered to be effective in hair growth, skin rejuvenation and wound healing Objectives: We studied the effect of LED irradiation using 630 nm, 830 nm and combination of the two wavelengths on hair growth promotion in vitro and in vivo. Methods: In in vitro study, we investigated cell proliferation in human hair dermal papilla cells (hDPCs) by MTT assay and measured the expression levels of apoptosis, cell cycle-related factors and canonical signaling-related factors such as β-catenin, GSK-3β by Western blot analysis. In in vivo study, anagen induction by LED was evaluated using C57BL/6 mice model. Results: We performed three types of combined irradiation method: 1) 830 nm irradiation after 630 nm irradiation. 2) 630 nm irradiation after 830 nm irradiation. 3) Simultaneous- irradiation of 630 nm and 830 nm. Among combined irradiation types the 830 nm irradiation after 630 nm irradiation was most effective for hDPC proliferation. According to this result, when we irradiate 630 nm, 830 nm and 630 nm irradiation after 830 nm irradiation on hDPCs, 830 nm irradiation was most effective for increasing proliferation of hDPCs. In C57BL/6 mice model, irradiation of 830 nm was also most effective for anagen induction. Conclusion: Our results demonstrate the effect of 830 nm irradiation for anagen induction through apoptosis, cell cycle and canonical signaling pathways in hDPCs and C57BL/6 mice model.