Impact of Red and Red/NIR OLEDs photobiomodulation effects towards promoting ADMSCs chondrogenic differentiation

Photobiomodulation (PBM) uses light to stimulate cellular responses and has the potential to enhance cartilage regeneration through mesenchymal stem cell (MSC) differentiation. This study investigates the chondrogenic potential of adipose-derived MSCs (ADMSCs) under PBM using Red (630 nm, 72.7 mW) and Red/NIR (630 nm and 845 nm, 59.7 mW) organic light-emitting diodes (OLEDs), with ADMSCs exposed to two distinct OLED panels (10.85 cm² surface area each). These wavelengths correspond to the absorption peaks of cytochrome c oxidase (CCO), a key mitochondrial enzyme involved in PBM-induced cellular bioenergetics. Cells were cultured in 24-well cell culture plate, receiving irradiance of 3.6 mW/cm² and 2.74 mW/cm², respectively. Exposure durations were 4.5, 14, and 23 minutes for Red OLED and 6, 18, and 30 minutes for Red/NIR OLED, delivering energy doses of 1, 3, and 5 J/cm² at 72-hour intervals. While Red/NIR OLED irradiation significantly enhanced ADMSC proliferation, it did not improve chondrogenic differentiation. In contrast, Red OLEDs consistently outperformed Red/NIR OLEDs as evidenced by stronger Safranin O staining, elevated collagen type II expression, and enhanced glycosaminoglycan (GAG) deposition via Alcian Blue staining. These findings underscore the superior efficacy of Red OLED-mediated PBM in promoting ADMSC differentiation toward the chondrogenic lineage and highlight the critical role of wavelength selection for PBM-based cartilage repair. Further exploration of the underlying mechanisms and optimization of PBM parameters is needed for improved clinical efficacies in tissue engineering and regenerative medicine.