Research advances in the pathogenesis and photodynamic therapy of pathological scars.

This review summarizes recent advances in the pathogenesis of pathological scars, including hypertrophic scars and keloids, and their photodynamic therapy (PDT). The formation of pathological scars involves fibroblast dysfunction, imbalanced ECM metabolism, chronic inflammation, aberrant activation of multiple signaling pathways (e.g., TGF-β/Smad, JAK/STAT, PI3K/Akt/mTOR), epigenetic regulation, and biomechanical factors, against a background of genetic susceptibility. As a minimally invasive and targeted therapy, PDT acts through the generation of reactive oxygen species (ROS) upon light activation of photosensitizers, leading to fibroblast death, suppression of collagen synthesis, interruption of key signaling pathways, and modulation of immune responses and angiogenesis, thereby effectively improving scars. Recent developments in novel photosensitizers and nanotechnology-based delivery systems have significantly enhanced the penetration and efficacy of PDT, offering new directions for its precise clinical application.