Photobiomodulation stimulates mitochondrial function and cell proliferation in meniscus-derived stem cells (MeSCs) via activation of TRPV1 channel

The meniscus is a crescent-shaped knee structure that helps stabilize the joint. This study investigates the molecular mechanism of photobiomodulation (PBM) at various wavelengths (400-405, 500-505, 700-710 and 1064 nm) and energy densities (3, 15, 30 and 60 J/cm²) affects mitochondrial function and cell proliferation in Meniscus-derived stem cells (MeSCs). We used LED light to irradiate human MeSCs and assessed intracellular calcium (Ca²⁺), cytochrome C oxidase (CCO) activity, nitric oxide (NO) concentrations, cell viability, mitochondrial membrane potential, reactive oxygen species (ROS) generation, and cell proliferation. The results showed that intracellular Ca²⁺ levels and ROS production increased as PBM energy density increased, whereas CCO activity and NO concentration remained unchanged. Irradiation at 700-710 and 1064 nm with energy densities of 3, 15, and 30 J/cm² improved proliferation and of MeSCs, with the most significant effect at 15 J/cm². However, all other PBM conditions reduced mitochondrial function and proliferative capacity. Inhibition of transient receptor potential vanilloid 1 (TRPV1) Ca²⁺ channel reduced PBM-induced elevations in Ca²⁺ and ROS at all wavelengths and prevented the associated changes in proliferation. These findings establish a dose-dependent effect of PBM on MeSCs mediated by TRPV1-Ca²⁺-ROS signaling and support its potential application in cytotherapy.