Polychromatic photobiomodulation accelerates diabetic wound repair via pro-angiogenic and anti-inflammatory mechanisms

Sarıkaya B., Batuhan Çetin F. B., Kaplanoğlu G. T., GÜMÜŞDERELİOĞLU M.

Journal of Photochemistry and Photobiology, vol.33, 2026 (Scopus)

Abstract

This study aimed to evaluate the histological and molecular effects of polychromatic photobiomodulation (PBM, 600–1200 nm), delivered at varying treatment frequencies, on wound healing in a streptozotocin (STZ)-induced diabetic rat model. To minimize inter-subject variability, three full-thickness excisional wounds were created on the dorsum of each diabetic rat and assigned to one of three groups: untreated Negative Control (NC), once-daily PBM (PBM1), or twice-daily PBM (PBM2). Treatments were administered using a polychromatic light source (600–1200 nm) placed 30 cm away from the wounds at an irradiance of 0.038 W/cm² with escalating fluences over a six-day period. Skin samples were harvested on Days 7 and 14 post-wounding and analyzed using Masson's Trichrome staining and immunohistochemistry for VEGF, VEGFR2, TGF-β, TGF-βR2, CD163, and TNF-α. The PBM2 regimen significantly enhanced re-epithelialization, collagen deposition, and angiogenesis compared to both PBM1 and untreated controls. Immunohistochemical analysis demonstrated early and pronounced expression of VEGF and CD163, along with sustained activation of TGF-βR2 in the PBM2 group. TNF-α expression was significantly reduced, particularly in the PBM2-treated wounds, suggesting accelerated resolution of inflammation and enhanced M2 macrophage polarization. Masson's Trichrome staining further confirmed the presence of denser and more organized collagen fibers in PBM2-treated wounds. Collectively, these findings indicate that twice-daily polychromatic PBM facilitates diabetic wound healing through synergistic pro-angiogenic, anti-inflammatory, and fibroproliferative pathways. This study supports the further optimization of PBM protocols for the effective management of chronic wounds.