305 Intraperitoneal cytostatic-loaded supramolecular hydrogel and intestinal anastomotic healing Bursting Pressure The median bursting pressure was 228 (200–255) mBar, 179 (55–260) mBar and 200 (86–253) mBar for saline, unloaded hydrogel and MMC-loaded hydrogel group, respectively. This was not significant different between the groups (Figure 1F). Microscopic Evaluation The anastomotic site of the rats which completed the experiment was microscopically scored by an experienced animal pathologist. No significant differences were found for fibroblast activity, inflammation and neoangiogenesis scores at the anastomotic site (Figure 2A). In all animals of the experimental groups (treated with MMC-loaded and unloaded hydrogel), we observed lymphangiectasia, oedema in the muscularis propria and vacuolated macrophages around the anastomotic site and in the surrounding peritoneal fat that contained foreign material (Figure 2C,D showing representative images). These histological observations were not seen in the control animals receiving normal saline (Figure 2B). Figure 2. (A) Histological analysis of animals at postoperative day 7: scores of fibroblast activity, inflammation and neoangiogenesis. Medians are indicated and whiskers show the Q1–Q3. (B) Hematoxylin & Eosin (H&E) staining of anastomotic site (10 × 5) of a saline-treated animal. (C) H&E staining of anastomotic site (10 × 5) of an animal that received unloaded hydrogel. (D) H&E staining of anastomotic site (10 × 5) of animal that received MMC-loaded hydrogel. Yellow dashed line indicates site of anastomosis, white arrow highlights fibroblast activity, black arrows show the lymphangiectasia and green arrows point the area with vacuolated macrophages. 13
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