Poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) thermogel as a novel submucosal cushion for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is a clinical therapy for early stage neoplastic lesions in the gastrointestinal tract. It is, however, faced with a crucial problem: the high occurrence of perforation. The formation of a submucosal fluid cushion (SFC) via a fluid injection is the best way to avoid perforation, and thus an appropriate biomaterial is vital for this minimally invasive endoscopic technique. In this study, we introduced an injectable thermogel as a novel submucosal injection substance in ESD. The hydrogel synthesized by us was composed of poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) triblock copolymers. The polymer/water system was a low-viscosity fluid at room temperature and thus easily injected, and turned into a non-flowing gel at body temperature after injection. The submucosal injection of the thermogel to create SFCs was performed in both resected porcine stomachs and living minipigs. High mucosal elevation with a clear margin was maintained for a long duration. Accurate en bloc resection was achieved with the assistance of the thermogel. The mean procedure time was strikingly reduced. Meanwhile, no obvious bleeding, perforation and tissue damage were observed. The application of the thermogel not only facilitated the ESD procedure, but also increased the efficacy and safety of ESD. Therefore, the PLGA-PEG-PLGA thermogel provides an excellent submucosal injection system, and has great potential to improve the ESD technique significantly.