title: Evaluating endogenous repair of focal cartilage defects in C57BL/6 and MRL/MpJ mice using 9.4T magnetic resonance imaging: A pilot study.
abstract: The use of magnetic resonance imaging (MRI) for evaluating joint injuries is often considered superior to radiography due to the capacity of MRI for visualizing both soft and hard tissues. While longitudinal studies regarding cartilage repair have been undertaken on patients and in larger animal models, a method has yet to be developed for mouse cartilage to be repeatedly and non-invasively evaluated over time. The aim of this pilot study was to investigate if morphological changes following a focal cartilage injury in mice could be measured by 9.4T magnetic resonance imaging. Focal cartilage defects were induced in the left knee of 4-6weeks old C57BL/6 and MRL/MpJ mice. At endpoints 0, 2, and 4weeks post-injury, legs were dissected out and imaged ex vivo. The defect could be detected by MRI immediately after injury, appearing as a hyperintense focal point and with size similar to that of the surgical tool used. Defects were visible in both strains up to 4weeks post-injury, although signal intensity decreased over time. One C57BL/6 in particular, displayed extensive fibrosis in the patellar tendon at 4weeks as assessed by histology, while the MR images of the same animal displayed a clear, structural distinction between the patella and the new tissue growth. Overall, our results suggest that MRI could be used for longitudinal studies in murine cartilage injury models to evaluate certain characteristics of repair not detectable through histology.
authors.affiliation: McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, AB, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Mak
authors.affiliation: McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, AB, Canada; Department of Surgery, University of Calgary, Calgary, AB, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Leonard
authors.affiliation: Experimental Imaging Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Foniok
authors.affiliation: Experimental Imaging Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Rushforth
authors.affiliation: Department of Radiology, University of Calgary, Calgary, AB, Canada; Experimental Imaging Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: J F
authors.initials: JF
authors.lastname: Dunn
authors.affiliation: McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, AB, Canada; Department of Surgery, University of Calgary, Calgary, AB, Canada; Department of Anatomy and Cell Biology, University of Calgary, Calgary, AB, Canada. Electronic address: rkrawetz@ucalgary.ca.
authors.forename: R
authors.initials: R
authors.lastname: Krawetz
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology*; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D010865:Pilot Projects
keywords: Cartilage; MRI; Mouse; Regeneration; Superhealer