Stimulating angiogenesis and post-ischemic tissue repair: Optimizing photobiomodulation parameters in vivo

Photobiomodulation (PBM) therapy, a non-invasive therapeutic approach utilizing red and near-infrared light at sub-thermal irradiances, presents significant potential in promoting angiogenesis and tissue repair. This study optimized PBM parameters and evaluated its effects in three complementary models: the chicken embryo chorioallantoic membrane (CAM), the aortic ring assay, and the mouse hindlimb ischemia (HLI) model. In the CAM model, PBM significantly enhanced vascular formation by increasing capillary branching and vessel density under optimized conditions. The aortic ring assay confirmed PBM's pro-angiogenic effects, demonstrating a marked increase in microvascular sprouting. In the mouse model, light propagation measurements at 652 nm and 730 nm were conducted to calculate attenuation coefficients for precise dosimetry. Daily PBM treatments at 652 nm following femoral artery ligation improved blood flow recovery at 14 days post-surgery. While minimal effects were observed at 5 days, likely attributable to initial hypoxia, PBM at 652 nm proved more efficient at 14 days, suggesting enhanced impact during later stages of vascular remodeling, when tissue oxygenation had improved. This study highlights the importance of precise wavelength selection and dosimetry to maximize PBM's therapeutic efficacy. These findings demonstrate that PBM effectively enhances vascular remodeling and tissue repair as tissue oxygenation recovers, representing a promising strategy for promoting recovery in ischemic conditions.