Coloview endoscopic system

Murine endoscopy and grading of inflammatory changes were performed as previously described [15 (link),23 (link)]. Briefly, endoscopy was performed in vivo prior to FMT scanning using a rigid murine colonoscope with a diameter of 1.9 mm and 10 cm length (Coloview Endoscopic System^®, KARL STORZ GmbH & Co. KG, Tuttlingen, Germany). Examinations were performed under sedation with isoflurane (0.3 l O₂/min; 1.5–2.0% isoflurane). To quantify the inflammation induced mucosal damage, the murine endoscopic index of colitis severity (MEICS) was used, which consists of five parameters to assess inflammation: Thickening of the colon wall, changes of the vascular pattern, presence of fibrin, granularity of the mucosal surface, and stool consistence [24 (link)].

Mice 6- to 8-week-old were fed ad libitum for one cycle with water containing 2% (wt/vol) DSS (MW 40,000 kDa; MP Biomedicals Inc.) for 7 days followed by 8 days with regular water without DSS (68 (link)). Mice were monitored daily for changes in body weight, stool consistency and rectal bleeding. These values were used to calculate the Disease Activity Index (DAI). Endoscopy was performed using Coloview endoscopic system (Karl Storz, Germany) at day 8. Colonic inflammation was scored according to MEICS (Murine Endoscopic Index of Colitis Severity) as described (69 (link)). Mice were sacrificed at indicated time points or at the end of the protocol for the isolation of colonic tissue. Histological scoring was performed on hematoxylin and eosin (H&E) stained colon sections as previously described (70 (link)). Scores of inflammation and epithelial damage were summed to produce the overall histological score. All histological assessments were performed in a blinded fashion, by two independent investigators.

Prior to sacrificing the mice on the respective days of analysis (POD1, 3 and 5), anastomotic healing was evaluated in vivo using a murine colonoscope (Coloview Endoscopic System^®, KARL STORZ GmbH & Co. KG, Tuttlingen, Germany). Endoscopic assessment of the anastomosis was performed under sedation with isoflurane. To quantify the severity of anastomotic leakage, the dehiscence of the anastomosis was measured using the imaging software ImageJ^® 1.49 (Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA). Dehiscence was defined as the length of the gap between the proximal and distal end of the anastomosis. Furthermore an endoscopic score was developed to assess the healing process of the anastomosis using visible criteria of anastomotic leakage. For this purpose the following parameters were analyzed and scored: 1 point: signs of inflammation without dehiscence, 3 points: dehiscence with signs of bleeding or fibrin formation involving less than 50% of the anastomosis, 6 points: dehiscence with signs of bleeding or fibrin formation involving > 50% of the anastomosis.