Potential of temperature-response collagen-genipin sol as a novel submucosal injection agent for endoscopic resection: Acute and chronic phase study using living animals

Objectives: We proposed a novel temperature-response collagen sol as a submucosal injection agent for endoscopic resection (ER) using pepsin-solubilized collagen (PSC) and genipin (Ge) in a prior study. This study aimed to evaluate the usefulness and safety of the sol (PSC/Ge) in acute and chronic phase experiments using living animals. Methods: In experiment 1, we performed endoscopic submucosal dissection (ESD) for six pigs using normal saline (NS), sodium hyaluronate (SH), and PSC/Ge. We compared the required amount of each agent per unit area and procedure time. In experiment 2, we created artificial ulcers with endoscopic mucosal resection (EMR) for five pigs using NS and PSC sol. We compared the artificial ulcer residual rate at 7 and 14 days after EMR, and the scarring rate at 14 days after EMR. Results: The required amount of agents per unit area for PSC/Ge (0.8 ± 0.8 mL/cm²) and SH (1.1 ± 0.8 mL/cm²) were significantly smaller than that for NS (1.8 ± 0.7 mL/cm²). The total procedure time did not have a statistical difference. The artificial ulcer residual rates were 47.3 ± 0.7% for NS and 40.3 ± 0.7% for PSC/Ge on day 7 (P = 0.51), and 15.0 ± 0.1% for NS and 10.2 ± 0.1% for PSC/Ge sol on day 14 (P = 0.35). The scarring rate on day 14 was 10% for NS and 20% for PSC/Ge. Conclusion: We demonstrated the feasibility of a novel temperature-response collagen gel as a submucosal injection agent for ER in the acute and chronic phase animal experiment.