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/cm 2 ) affects mitochondrial function and cell proliferation in Meniscus-derived stem cells (MeSCs). We used LED light to irradiate human MeSCs and assessed intracellular calcium (Ca 2 ⁺), 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 Ca 2 ⁺ 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/cm 2 improved proliferation and of MeSCs, with the most significant effect at 15 J/cm 2 . However, all other PBM conditions reduced mitochondrial function and proliferative capacity. Inhibition of transient receptor potential vanilloid 1 (TRPV1) Ca 2+ channel reduced PBM-induced elevations in Ca 2+ 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-Ca 2 ⁺-ROS signaling and support its potential application in cytotherapy.