Light Source Matching Strategies for Optimal Treatment Efficacy of HMME and <i>m</i> ‐THPC in Photodynamic Therapy of Vascular Lesions

Abstract Objective This study aims to compare the therapeutic effects of hematoporphyrin monomethyl ether (HMME) and meta ‐tetrahydroxyphenylchlorin ( m ‐THPC) under single‐wavelength and dual‐wavelength light irradiation in photodynamic therapy (PDT), and aims to optimize light source matching strategies to enhance targeted treatment of vascular lesions. Methods This study employed the ABDA probe assay to evaluate the in vitro reactive oxygen species (ROS) generation efficiency of two photosensitizers (HMME and m ‐THPC) under 410, 532, 653 nm, and dual‐wavelength (410 + 653 nm) irradiation. Using Leghorn chicken comb as a vascular malformation model, we further assessed in vivo vascular damage effects, thermal responses, tissue‐level ROS production, and apoptosis rates. Results This study demonstrated that HMME exhibited optimal photodynamic efficacy at 410 nm, while m ‐THPC maintained substantial photodynamic efficacy at both 410 and 653 nm, with the dual‐wavelength combination (410 + 653 nm) showing complementary activation for m ‐THPC but reduced efficacy for HMME. The 532 nm wavelength, though effective for vascular damage, caused significant thermal injury and non‐specific apoptosis of non‐target cells, highlighting its clinical limitations. Histopathological analysis confirmed that 410 and 653 nm irradiation selectively targeted vasculature with minimal epidermal damage, whereas 532 nm led to widespread tissue necrosis. ROS generation and apoptotic assays revealed that HMME's cytotoxicity was strongest at 410 nm, while m ‐THPC performed well across multiple wavelengths, and particularly benefited from dual‐wavelength activation. Conclusion Photosensitizer activation efficiency is highly wavelength‐dependent, with HMME performing best at shorter wavelengths (410 nm) while m ‐THPC maintains considerable efficacy at longer wavelengths (653 nm). The dual‐wavelength combination (410 + 653 nm) can partially overcome limitations of single wavelengths, providing references for clinical light source optimization.