Improved reperfusion following alternative surgical approach for experimental stroke in mice

Trotman-Lucas, Melissa; Wong, Raymond; Allan, Stuart M.; Gibson, Claire L.

Abstract

Background: Following ischemic stroke, recanalisation and restoration of blood flow to the affected area of the brain is critical and directly correlates with patient recovery. In vivo models of ischemic stroke show high variability in outcomes which may be due to variability in reperfusion. We previously reported that a surgical refinement in the middle cerebral artery occlusion (MCAO) model of stroke, via repair of the common carotid artery (CCA), removes the reliance on the Circle of Willis for reperfusion and reduced infarct variability. Here we further assess this refined surgical approach on reperfusion characteristics following transient MCAO in mice.

Methods: Mice underwent 60 min of MCAO, followed by either CCA repair or ligation at reperfusion. All mice underwent laser speckle contrast imaging at baseline, 24h and 48h post-MCAO.

Results: CCA ligation reduced cerebral perfusion in the ipsilateral hemisphere compared to baseline (102.3 ± 4.57 %) at 24h (85.13 ± 16.09 %; P [less than] 0.01) and 48h (75.04 ± 12.954 %; P [less than] 0.001) post-MCAO. Repair of the CCA returned perfusion to baseline (94.152 ± 2.44 %) levels and perfusion was significantly improved compared to CCA ligation at both 24h (102.83 ± 8.41 %; P [less than] 0.05) and 48h (102.13 ± 9.34 %; P [less than] 0.001) post-MCAO.

Conclusions: Our findings show CCA repair, an alternative surgical approach for MCAO, results in improved ischemic hemisphere perfusion during the acute phase.

Citation

Trotman-Lucas, M., Wong, R., Allan, S. M., & Gibson, C. L. (2020). Improved reperfusion following alternative surgical approach for experimental stroke in mice. F1000Research, 9, https://doi.org/10.12688/f1000research.22594.1

• Journal Article Type: Article
• Acceptance Date: Feb 26, 2020
• Online Publication Date: Mar 13, 2020
• Publication Date: Mar 13, 2020
• Deposit Date: Mar 5, 2020
• Publicly Available Date: Mar 13, 2020
• Journal: F1000Research
• Electronic ISSN: 2046-1402
• Publisher: F1000Research
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Article Number: 188
• DOI: https://doi.org/10.12688/f1000research.22594.1
• Keywords: Ischemia, Cerebral stroke, Reperfusion, Cerebral blood flow
• Public URL: https://nottingham-repository.worktribe.com/output/4094319
• Publisher URL: https://f1000research.com/articles/9-188/v1
• Additional Information: Referee status: Approved, Approved with reservations; Referee Report: 10.5256/f1000research.24941.r61343, Arshad Majid, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK, 30 Mar 2020, version 1, 1 approved, 1 approved with reservations; Referee Comment: claire gibson; Posted: 30 Mar 2020; Thank you for this review. In response to the specific point about lesion volume - we did not investigate that within this study as we have previously (Trotman-Lucas M, Kelly ME, Janus J, et al.: An alternative surgical approach reduces variability following filament induction of experimental stroke in mice. Dis Model Mech. 2017; 10(7): 931–938) demonstrated the impact of this refined surgical approach on lesion volume.; Referee Comment: Arshad Majid; Posted: 05 May 2020; Thank you for your response.; Referee Report: 10.5256/f1000research.24941.r61345, Brad Sutherland, School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia, 07 Apr 2020, version 1, 1 approved, 1 approved with reservations; Referee Comment: claire gibson; Posted: 29 Apr 2020; The Laser Speckle Contrast Imaging method has great spatial and temporal resolution but does not provide any depth assessment of CBF changes in the brain. It only provides a measurement of CBF on the surface of the brain. Therefore, all that can be stated from this study is that pial CBF can be improved post-MCA during CCA repair compared to the CCA ligated method, as we do not know from this imaging technique whether the underlying brain is fully reperfused. Some discussion around this would be useful. Response: Please see added section into discussion. The Laser Speckle Contrast Imaging was conducted at baseline (prior to MCAO), 24h post-MCAO and 48h post-MCAO. However, there was no apparent assessment during MCAO to show that a stroke had actually occurred. How can you confirm that these animals actually had a stroke with no CBF assessment during MCAO? Response: As now stated in the methods section of the paper the drop in CBF during MCAO was confirmed using laser doppler flowmetry. The sustained (48h) changes shown in Figure 1 are interesting. It would have been excellent to have shown how these CBF values are associated with changes in neurological deficit (could be done by a neuroscore) or infarct volume at 48 hours. Were the brains assessed for this? Response: We would agree that any further analysis under these experimental conditions would be useful. However, that was beyond the remit of this current study which was powered to answer the specific research question. We have previously reported the effect of this modified surgical approach on lesion volume (see Trotman et al., 2017, Disease Models & Mechanisms). The CCA ligated results show sustained hypoperfusion on the surface of the brain for 48 hours. Some extended discussion on how this could impact the development of the lesion and chronic injury would be useful, particularly since chronic occlusion of the CCA is used in vascular dementia studies with chronic neurodegeneration and impaired cognition present. Response: Please see amended section in discussion. There are many studies showing that CBF in the contralateral hemisphere can be altered during MCAO and during reperfusion (e.g. Lavy et al 1975 Stroke 6:160-31; Taheri et al 2019 Transl Neurosci Res Rev 2:27-372; Premilovac et al 2020 JCBFM 271678X209054933 and others). Given that the quantification of the ipsilateral CBF is a % of the contralateral, any changes in CBF in the contralateral hemisphere in response to MCAO or reperfusion could alter the reference point for this analysis. Some discussion should be added about this as a limitation. Response: Please see amended section in discussion. The second last sentence of the discussion “Validating the use of CCA repair…” is an incomplete sentence and will need rewritten. Response: This sentence has been amended.; Grant Information: The author(s) declared that no grants were involved in supporting this work; Copyright: This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Data associated with the article are available under the terms of the Creative Commons Zero "No rights reserved" data waiver (CC0 1.0 Public domain dedication).