Search in the Abstract Database

Search Abstracts 2011

* = Presenting author

P037. Bench-top-MR-imaging as a method to monitor acute experimental colitis in a mouse model

M. Hermann1, J. Walldorf2, M. Porzner2, S. Ebensing2, P. Stock2, H. Metz3, K. Mäder3, M.M. Dollinger2, T. Seufferlein2, B. Christ2

1Martin-Luther-University, Halle, Germany; 2Department of Internal Medicine I, Martin-Luther-University, Halle-Wittenberg, Germany; 3Department of Pharmacy, Martin-Luther-University, Halle-Wittenberg, Germany

Introduction: The standard procedure to study experimental colitis is determination of colon length and thickness as well as histological examination. As these parameters are determined post mortem, they are not useful to follow up colitis in individual animals. While repeated MR-imaging of individual animals is possible, it is typically a time and space consuming method with high costs. The aim of this study was to evaluate bench-top-MR-Imaging, using a small and potentially cost and time efficient MR-analyzer in a model of acute experimental colitis.

Methods: 27 male balb/c mice were treated with 4% dextran-sulfate-sodium p.o. for 9 days to induce acute colitis. Of these, 6 mice were treated daily with a neurotrophic compound (NC) and 5 mice with 1 mg of infliximab (INF) i.p. on day 3. Clinical scoring was performed every day of the treatment. To allow reassessment of identical colonic segments by bench-top-MRI, the distal colon was labeled endoscopically injecting a suspension of ink and iron oxide using a micro colonoscope (Karl Storz, Image 1®). Colon wall thickness was measured in cross sectional areas by bench-top-MRI (MARAN-DI by Oxford-Instruments, 0.5 Tesla permanent magnetic system) using a bentonit-enema to improve the demarcation of the colonic wall in vivo. On day 9 the animals were sacrificed and colon length and thickness was determined.

Results: Endoscopic labeling of a specific colonic segment allowed repeated measurements of the wall thickness of identical colonic segments at predefined time points. At the end of the learning curve, MR-scan time was approximately 10 min. per mouse. The NC and INF treated groups showed a more modest increase of mean colon wall thickness (NC 138±51%; INF 201±44%) compared to the DSS treated control group with a peak increase on day 6 (DSS 228±55%, NC vs. DSS p < 0.05). This correlated to the weight loss (DSS 19±5% of body weight, NC 14±9%, INF 16±11%), the clinical colitis score on day 9 (DSS 2.8±0.43 of total 3 points; NC 1.6±0.9; INF 2.2±0.8) and the macroscopic colon length (DSS 54±5 mm, NC 69±6, INF 71±4, p < 0.05) as determined after termination of the mice on day 9.

Conclusions: Determination of the wall thickness of the distal colon at a predefined segment by bench-top-MR-imaging, the development of experimental colitis can be adequately monitored. It is possible to detect relevant differences between the experimental groups as confirmed by clinical scores and macroscopic findings. Our results show that bench-top-MR-Imaging is a reliable tool in in-vivo evaluating of experimental colitis in mice. Luminal colonic labeling via colonoscopy increased the precision of the MR-Imaging. Short examination time, sufficient image quality and low technical effort make this method attractive for further investigation.