Reply to Murakami et al.

We appreciate the comments from Murakami et al. regarding our study [1], and are grateful for the opportunity to address their points.

As the authors point out, it remains unclear how the polyglycolic acid (PGA) shielding method works on endoscopic submucosal dissection (ESD)-induced ulcers. Our study could not assess the mechanism because it was a clinical study to investigate the efficacy of the PGA shielding method for preventing post-ESD bleeding.

To date, only two studies have investigated the mechanism of PGA shielding for ESD-induced ulcers in an animal model [2] [3]. Takao et al. reported that histological examination of ESD-induced ulcers on which PGA sheets with fibrin glue were applied revealed no excessive inflammation, necrosis or infection in a porcine model [2]. Tsujimoto et al. reported that the fibrin glue used in the PGA shielding method has a protective effect against gastric juice and reduces tissue damage, and that the scaffold function of PGA fabric induces better granulation formation at an earlier phase, resulting in excellent long-term tissue repair in a canine model [3]. These two studies demonstrated the protective effect of PGA shielding, but in both studies histological examinations were performed at least 3 days after ESD. Therefore, whether acute inflammation occurs in early phases, as Murakami et al. suggest, was not assessed. Inflammatory reaction against PGA sheets immediately after shielding might lead to early-phase bleeding after ESD, but post-ESD bleeding occurs most frequently within 24 hours after ESD procedures [4]. In this regard, it is questionable whether PGA shielding truly aggravates early-phase bleeding. More investigations would be essential.

At present there are several types of biodegradable materials available, and we totally agree with the authors that we should deepen our understanding of those materials and their mechanisms in order to apply them more effectively in endoscopic fields.

• References

• 1 Kataoka Y, Tsuji Y, Hisrasawa K. et al. Endoscopic tissue shielding to prevent bleeding after endoscopic submucosal dissection: a prospective multicenter randomized controlled trial. Endoscopy 2019; 51: 619-627
• 2 Takao T, Takegawa Y, Shinya N. et al. Tissue shielding with polyglycolic acid sheets and fibrin glue on ulcers induced by endoscopic submucosal dissection in a porcine model. Endosc Int Open 2015; 3: E146-151
• 3 Tsujimoto H, Yamanaka K, Miyamoto H. et al. A basic study of the effect of the shielding method with polyglycolic acid fabric and fibrin glue after endoscopic submucosal dissection. Endosc Int Open 2016; 4: E1298-E1304
• 4 Goto O, Fujishiro M, Oda I. et al. A multicenter survey of the management after gastric endoscopic submucosal dissection related to postoperative bleeding. Dig Dis Sci 2012; 57: 435-439