Localized Photodynamic Therapy Using a Photosensitizer-Integrated Silicone-Covered Self-Expanding Catheter in Rabbit Esophagus Model

Abstract

Background: This study aimed to investigate the mechanical properties of aluminum (III)- phthalocyanine chloride tetrasulfonic acid (Al-PcS4)-integrated silicone-covered self-expanding metal stent (SEMS) and evaluate the efficacy and safety of localized photodynamic therapy (PDT) using an Al-PcS4-integrated silicone-covered self-expanding catheter in an in vivo rabbit esophageal model. Methods: An Al-PcS4 integrated silicone covered self-expanding catheter was fabricated, and assessed mechanical properties of SEMS. The localized PDT procedure was performed in 24 rabbits using the catheter system, and 6 sham controls underwent no PDT treatment. Follow-up endoscopic and esophagographic examinations, along with histological and immunohistochemical evaluation, were performed at 1, 7, 14, and 28 days post-procedure. Results: The Al-PcS4-integrated silicone-covered SEMS exhibited the highest radial and axial forces compared to uncovered and silicone-covered SEMS. PDT-treated groups showed significant mucosal changes and mild luminal narrowing on day 1, but these effects gradually resolved by day 28. Histological analysis revealed acute tissue damage, including reduced epithelial thickness and increased submucosal fibrosis, which showed progressive recovery by day 28. Immunohistochemical findings confirmed increased TUNEL, caspase-3, indicating apoptosis, as well as HSP70, and FGFR1 overexpression associated with wound healing and tissue remodeling. Conclusion: Localized PDT using the Al-PcS4-integrated silicone-covered self-expanding catheter effectively induced targeted tissue damage and triggered dynamic wound healing processes in the rabbit esophagus without severe complications. This suggests the substantial potential for this minimally invasive local therapy in treating obstructive diseases in the endoluminal organs.Docto