Sprayable gelatin microparticles prevent delayed gastric bleeding in an anticoagulated swine model

Delayed bleeding following endoscopic mucosal resection or endoscopic submucosal dissection is a serious concern in patients receiving anticoagulant therapy. We previously established an experimental animal model of delayed gastric bleeding following endoscopic resection under controlled anticoagulation. In this study, we aimed to evaluate the potential preventive effect of hydrophobized microparticles (hMPs), a novel sprayable wound-covering material derived from Alaska pollock gelatin, in preventing delayed bleeding. Twelve gastric mucosal defects were created by endoscopic mucosal resection with ligation in three CLAWN miniature swine. To induce delayed bleeding, systemic heparin was administered after confirming an activated clotting time greater than 220 s. hMPs were endoscopically sprayed into each ulcer base (200 mg/ulcer). Endoscopic examination was performed 24 h later. The primary endpoint was the presence or absence of delayed bleeding. Secondary endpoints included hMP retention, ulcer coverage rate, presence of exposed vessels, and vascular coverage by hMPs. During the 24-hour observation period, no delayed bleeding was observed in any of the three CLAWN miniature swine treated with hMPs. Hemoglobin levels on Day 1 remained stable in all swine. hMPs were present in 100% of the ulcers. Complete ulcer base coverage (100%) was achieved in 55.6% (20/36) of the sections, with ≥ 50% coverage observed in all sections. Exposed vessels were identified in 36.1% (13/36) of ulcers, and all were covered with hMPs. Endoscopic spray application of hMPs demonstrated strong adhesion to gastric ulcers and was associated with the absence of delayed bleeding in this short-term experimental model. These findings suggest that hMPs may represent a promising strategy for reducing the risk of delayed bleeding after gastrointestinal endoscopic surgery.