Determining the source of variability within experimental stroke models

Efficacy of stroke interventions are tested using rodent middle cerebral artery occlusion (MCAO) models of focal brain ischemia but these have a poor record of translating into clinically effective treatments. The majority of experimental stroke studies use lesion volume as the primary outcome measure. However, variability in MCAO lesion volume is high with significant differences generally tested using parametric analyses requiring a normal data distribution. Data from my laboratory over the last ten years (and confirmed by others) shows that MCAO lesion volume data is not normally distributed and results in a bimodal distribution of small (purely striatal) and large (striato-cortical) lesions. We aim to determine (i) whether variability in MCAO lesion data is due to differences in cerebrovascular anatomy and, (ii) whether refinement of the surgical technique can improve outcome reproducibility. Rodents show a large variability in the Circle of Willis and studies have shown this to produce variability in lesion volume thus, requiring increased animal numbers to achieve statistical significance. However, traditional methods to assess the Circle of Willis anatomy are conducted post-mortem following the induction of MCAO. Firstly, we will assess, using MRI, whether the reported variability in outcome following MCAO is dependent upon the anatomy of the Circle of Willis and if so, can we develop a screening technique to identify 'suitable' mice to undergo MCAO and therefore reduce the number of animals undergoing MCAO.  In addition, we will assess whether a refinement in the surgical approach used to permit reperfusion followng MCAO can be applied in mice.  This will allow reperfusion to occur irrespective of the completeness of the Circle of Willis which is currently the main limitation in determining the effectiveness of reperfusion. This should reduce the variability in reperfusion associated experimental stroke models and reduce the number of animals used.

Trotman-Lucas M et al. (2019). Middle Cerebral Artery Occlusion Allowing Reperfusion via Common Carotid Artery Repair in Mice. Journal of Visualized Experiments 143: e58191. doi:10.3791/58191

Trotman-Lucas M et al. (2017).  An alternative surgical approach reduces variability following filament induction of experimental stroke in mice. Disease Models & Mechanisms 10: 931-938. doi:10.1242/dmm.029108

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Pilot study grant



Principal investigator

Dr Claire Gibson


University of Leicester


Dr Michael Kelly

Grant reference number


Award date

Nov 2014 - Nov 2015

Grant amount