The effect of 807-nm light-emitting diode photobiomodulation on peripheral nerve injury

Photobiomodulation (PBM) has demonstrated potential in promoting peripheral nerve regeneration. However, there is a limited and inconclusive study on the application of light-emitting diode (LED) for nerve injury repair. In this study, we designed an 807-nm LED device with high luminous uniformity to investigate the effects of LED-based PBM on peripheral nerve injury repair. RSC96 cells were utilized as the target cells and optimal light parameters were selected based on ATP concentration, CCK-8 assays, PCR, and immunofluorescent staining. One-way analysis of variance and Student's t-test was used for statistical tests. LED irradiation at 10 mW/cm² for 30 min effectively enhanced Schwann cell proliferation, neurotrophic factor secretion, and MBP synthesis. To translate the cellular light parameters for animal studies, the transmittance through freshly obtained rat skin and biceps femoris muscle was assessed, and the transmittance was approximately 30%. After directly daily irradiating the sciatic nerve injury area in rats for 21 days at 33 mW/cm² for 30 min, we used gait analysis, immunofluorescence staining, muscle wet weight ratio, Masson staining, and transmission electron microscopy to evaluate nerve recovery. LED irradiation significantly improved sciatic nerve index, increased MBP staining intensity, and enhanced myelin sheath thickness, nerve diameter, and axon diameter. These results indicated the feasibility of LED-based PBM as a treatment method for peripheral nerve injuries.