Histological and biochemical effects of preventive and therapeutic vascular photobiomodulation on rat muscle injury

Abstract

The intravascular or transcutaneous application of photobiomodulation (PBM) over blood vessels (vascular photobiomodulation, VPBM) has been used for the treatment of inflammatory and chronic conditions with promising systemic results. This study evaluated the VPBM effects on a model of muscle regeneration after acute injury and compared the outcomes of preventive and therapeutic VPBM. Transcutaneous VPBM was administered over the rat's main tail vein. Serum levels of creatine kinase (CK), aspartate aminotransferase (AST), and lactate were evaluated and muscles were processed for macroscopic and microscopic analysis. Preventive and therapeutic VPBM led to decreased inflammatory infiltrate, edema, and myonecrosis but with an increase in immature muscle fibers. CK, AST, and lactate levels were lower in the groups treated with VPBM (lowest concentrations in preventive VPBM application). Preventive and therapeutic VPBM were capable of exerting a positive effect on acute muscle injury repair, with more accentuated results when preventive VPBM was administered.

Systemic vascular photobiomodulation accelerates the recovery of motor activity in rats following spinal cord injury

“…A recent published study showed in an acute muscle injury animal model that VPBM promoted a reduction in macroscopic injury size, reduction of inflammatory infiltration and myonecrosis after 5 days and an increase of immature muscle fibers. In addition, this study also showed a reduction in biochemical markers related to muscle injury even to the control group 25 . In context macrophages/monocytes are key cells in muscle repair coordination and macrophages/microglia are essential to the promotion of neuronal survival 14 …”

“…In addition, this study also showed a reduction in biochemical markers related to muscle injury even to the control group. 25 In context macrophages/monocytes are key cells in muscle repair coordination and macrophages/microglia are essential to the promotion of neuronal survival. 14 Functional improvements described in the literature in experimental studies employing PBM administered locally after SCI are attributed to changes on the cellular and molecular levels, with a reduction in the inflammatory process through the modulation of mediators, such as IL1-β, a reduction in edema at the injury site and the functional restoration of damaged mitochondria, thereby avoiding cell death.…”

“…The animals were submitted VPBM for 14 consecutive days, as shown in the timeline presented in Figure 1. VPBM was administered at 1‐point in the region of the caudal vein/artery 25 for 80 s. For LLL, the animal was manually restrained and light was administered at a 90° angle between the emitter and skin to avoid the refraction of the beam. The power of the laser device was measured using the Laser Check power meter (MM Optics).…”

“…The dosimetric parameters are listed in Table 1. As no studies were found that administered VPBM in animal models of SCI, the choice of dosimetric parameters was based on studies involving local PBM in a peripheral nerve injury model, 26 VPBM in an acute muscle injury model, 25 and in the recovery following sciatic nerve injury in rats, where the same laser parameters showed a positive modulation of functioning and neuromuscular changes 27 …”