Comparative Effects of 808 nm Laser and Multi-Wavelength Near-Infrared Photobiomodulation on Osteogenic Protein-Associated Fluorescence in MG-63 Osteoblast-Like Cells

Introduction: This study, for the first time, investigated the effects of polychromatic multi-wavelength near-infrared (PMNI) photobiomodulation (PBM) on osteoblast-associated protein fluorescence in MG-63 osteoblast-like cells, examining the relationship between exposure, timing (immediate and 24 h post-treatment), and irradiation wavelength. Specifically, cells were exposed to a proprietary blend of light-emitting diodes (wavelengths 775, 845 and 940 nm) or to a single-wavelength 808 nm diode laser. Methods: MG-63 osteoblast-like cells were exposed to the multi-wavelength LED for 30 or 60 s or to the 808 nm diode laser for 33 or 100 s. Protein-associated fluorescence was assessed immediately and 24 h following irradiation. Immunofluorescence intensity for alkaline phosphatase (ALP), RUNX2, BMP-2, COL-1, OPN and OCN was quantified using ImageJ software (version 1.54t). Results: PMNI-LED increased osteogenic protein-associated fluorescence across all six markers under at least one irradiation condition, with the largest response observed for BMP-2 following 30 s irradiation assessed immediately. The magnitude and direction of responses varied according to exposure duration and assessment time. In contrast, the 808 nm laser produced a more selective response pattern, with persistent reductions in ALP and RUNX2 fluorescence, increases in OPN under several irradiation conditions, and smaller marker-specific increases in BMP-2, OCN and COL-1. Conclusion: MG-63 osteoblast-like cells respond to photobiomodulation with near-infrared light from both polychromatic LED and single diode light sources. The fluorescence intensity associated with osteogenic protein markers was influenced by wavelength composition, radiant exposure and assessment time following PBM therapy.