Impact of preventive and therapeutic vascular photobiomodulation on collagen deposition and distribution in experimental model of acute muscle injury.

Abstract

Photobiomodulation (PBM) improves collagen distribution and organization in muscles during regeneration, with most data focusing on localized irradiation. Vascular PBM (VPBM) may promote overall muscle recovery and reduce downtime. The aim of the present study was to investigate the effects of VPBM on collagen deposition in muscle tissue after acute injury, comparing preventive (before injury) and therapeutic (after injury) applications. Wistar rats (n = 85) were randomly distributed into groups: Control; Injury; Non-injury + VPBM; Prior-VPBM + Injury; and Injury + Post-injury VPBM. Muscle injury was induced by cryoinjury. VPBM (780 nm, 40 mW, 10 J/cm², 3.2 J) was applied to the caudal artery/vein. Euthanasia occurred on Days 1, 2, 5, and 7 post-injury. Samples were stained with Picrosirius Red to determine areas of collagen and extracellular matrix (ECM). The results revealed increased collagen in the VPBM-treated groups. In the five-day experimental period, the ECM area was significantly lower in the VPBM groups. In conclusion, VPBM modulated collagen deposition and ECM area, depending on the timing of irradiation.