The effect of red light irradiation on the proliferation of mesenchymal stem cells

Abstract

Objective To study the effect of red light on the proliferation of mesenchymal stem cells (BMSCs). Methods BMSCs were isolated from Sprague-Dawley rats and cultured in vitro. They were irradiated with red light delivered by a light-emitting diode placed 2 cm above the cell layer. The light had a wavelength of 620 nm and a maximum power of 1 W. The measured optical power density was 6.67 mW/cm2. The cells were randomly divided into a control group and three experimental groups. The control group was not irradiated, while the other 3 groups were irradiated at 0.5, 1 and 2 J/cm2 for 75 s, 150 s or 300 s, repeated twice with an interval of 12 hours. Forty-eight hours after the irradiation, cellular proliferation was evaluated using CCK-8 assays and DNA replication was quantified with a Cell-Light EdU. Changes in the cell cycle parameters were detected using flow cytometry. Results After the irradiation, the proliferation and DNA replication of the experimental group were significantly strengthened, while the cell growth cycle was significantly shortened compared with the control group, especially in the group irradiated at 0.5 J/cm2. Conclusion Low-energy red light irradiation can promote the proliferation of mesenchymal stem cells in vitro by enhancing DNA replication and shortening the cell growth cycle. Key words: Low-energy phototherapy; Light-emitting diodes; Photobiomodulation; Mesenchymal stem cells; Proliferation