A Modified Model Preparation for Middle Cerebral Artery Occlusion Reperfusion

Published: May 31, 2024

doi:

Rong Ma, Hongyan Yang, Jianlong Liang, Danni Lu, Qian Xie, Xuxin Zeng, Jialiang Guo

¹School of Medicine,Foshan University, ²School of Medicine,Shaanxi University of International Trade and Commerce

Summary

This protocol describes the process of preparing for middle cerebral artery occlusion reperfusion via the common carotid artery.

Abstract

The middle cerebral artery occlusion reperfusion (MCAO/R) model is crucial for understanding the pathological mechanisms of stroke and for drug development.However, among the commonly used modeling methods, the Koizumi method often faces scrutiny due to its ligation of the common carotid artery (CCA) and its inability to achieve adequate reperfusion. Similarly, the Longa method has been criticized for disconnecting and ligating the external carotid artery (ECA). This study aims to introduce a modified model preparation method that preserves the integrity of the ECA, involves inserting a monofilament nylon suture through the CCA, repairing the ligated CCA incision, and maintaining reperfusion from the CCA. Reperfusion of blood flow was confirmed using laser speckle flow imaging. Evaluation methods such as the Longa scale, Modified Neurological Severity Score, triphenyltetrazolium chloride (TTC) staining, and immunofluorescence labeling of neurons demonstrated that this approach could induce stable ischemic nerve damage. This modified MCAO/R model protocol is simple and stable, providing valuable guidance for practitioners in the field of cerebral ischemia.

Introduction

According to the World Health Organization, stroke has remained the second leading cause of death worldwide for the past decade, with a high incidence rate, high mortality, and high disability rate¹^,². As the global population ages, the incidence of stroke is expected to increase in developing countries, potentially becoming the leading cause of premature death and disability in adults. Additionally, there is a trend for strokes to occur at a younger age³. The loss of the labor force after a stroke also places a heavy burden on families and society⁴. Therefore, the development of safe and effective treatments poses a major challenge in stroke research.

Animal models serve as crucial tools for studying the prevention and treatment of human diseases. The successful translation of stroke treatment strategies relies on the reproducibility and reliability of stroke animal models⁵^,⁶. The middle cerebral artery (MCA) is a common site for clinical stroke, making the MCAO model the closest model to human ischemic stroke. The MCAO model, prepared using the suture method, has been favored by researchers due to advantages such as no craniotomy and easy control of ischemic time. It has been utilized in over 40% of neuroprotective experiments⁷. However, despite its numerous advantages, the operational details of this model remain a controversial topic for many researchers.

For the suture-induced middle cerebral artery occlusion (MCAO) model, reperfusion occurs by withdrawing the suture. Currently, two main methods are used for suture insertion: Koizumi’s method⁸ and Longa’s method⁹. In Koizumi’s method, the suture enters the internal carotid artery (ICA) mainly through the common carotid artery (CCA) incision, while in Longa’s method, it passes through the severed external carotid artery (ECA) into the ICA. During reperfusion, the Koizumi method requires permanently ligating the CCA incision and relies on the circle of Willis for reperfusion¹⁰. However, some studies suggest that effective reperfusion cannot be achieved solely through the compensatory supply of the circle of Willis after losing the CCA supply. Moreover, the circle of Willis exhibits high anatomical variability, especially in C57Bl/6 mice, increasing infarction variability and reducing experimental data reliability. Consequently, this method has been increasingly questioned by researchers¹¹.

Longa’s method involves inserting a suture through the severed ECA and then permanently ligating the internal carotid artery (ICA) once the suture is withdrawn. This preserves CCA patency, allowing blood perfusion up to 100% of baseline values. However, this method necessitates separating the external carotid artery and small arterial branches, cutting them off, or electrocoagulating them, making the procedure challenging. It also disrupts the brain’s complete blood flow structure, which differs from the clinical patient’s state¹². Importantly, studies indicate that cutting or ligating the ECA can cause ischemic lesions in the muscles controlling chewing and swallowing, affecting animal diet and leading to postoperative animal death and severe sensory and motor damage in rats¹³^,¹⁴.

Hence, a modified model preparation method is urgently needed to address these issues. This study introduces a modified MCAO modeling method that repairs the CCA insertion incision and achieves effective reperfusion. The procedure is simple, practical, and feasible, inducing significant neurological damage and replicable infarct lesions and providing valuable guidance for stroke researchers.

Protocol

The experimental protocol was conducted in compliance with the Use of Laboratory Animals and Institutional Animal Care and Use Committee guidelines at Chengdu University of Traditional Chinese Medicine (Record number: 2019-DL-002). All animal research data have been documented following the ARRIVE (Animal Research: Reporting In Vivo Experiments) guidelines. Male Sprague Dawley (SD) rats weighing 250 g ± 20 g and aged 6-8 weeks were utilized for this study. The specifics regarding the animals, reagents, and …

Representative Results

Laser speckle flow imaging demonstrated that prior to the occlusion of the monofilament nylon suture, there was abundant blood flow in the middle cerebral artery (MCA) area, and the baseline blood flow values of the rats were recorded. Following the occlusion of the MCA, the blood flow value on the ischemic side of the brain rapidly decreased. Before withdrawing the suture, the blood flow values on the ischemic side were rechecked to confirm whether the suture was occluding the MCA. The results indicated only a slight ch…

Discussion

The middle cerebral artery occlusion (MCAO) model induced by a monofilament nylon suture is the most common method used for preparing MCAO models. This approach is widely adopted in preclinical studies and has gained recognition from many practitioners due to its simplicity, lack of need for craniotomy, minimal surgical trauma, and ability to achieve reperfusion.

There are two classical surgical techniques for intraluminal filament MCAO: the Koizumi method⁸ and the Long…

Divulgazioni

The authors have nothing to disclose.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (82173781 and 82373835), Postdoctoral research project (BKS212055), Science and Technology Innovation Project of Foshan Science and Technology Bureau (2320001007331), Guangdong Basic and Applied Basic Research Foundation (2019A1515010806), Key Field Projects (Intelligent Manufacturing) of General Universities in Guangdong Province (2020ZDZX2057), and the Scientific Research Projects (Characteristic Innovation) of General Universities in Guangdong Province (2019KTSCX195).

Materials

Animal anesthesia system	Rayward Life Technology Co., Ltd	R500IE
Animal temperature maintainer	Rayward Life Technology Co., Ltd	69020
Cy3 secondary antibody	Wuhan Saiweier Biotechnology Co., Ltd	GB21303
DAP1 antibody	Wuhan Saiweier Biotechnology Co., Ltd	G1012
DCX antibody	Wuhan Saiweier Biotechnology Co., Ltd	GB13434
Goat serum	Beyotime Biotechnology Co., LTD	C0265
GraphPad Prism	GraphPad Software	GraphPad Prism 8.0
ImageJ	National Institutes of Health	ImageJ software
Isofluran	Rayward Life Technology Co., Ltd	R510-22
Laser speckle blood flow imaging system	Rayward Life Technology Co., Ltd	PeriCam PSI NR
MAP-2 antibody	Wuhan Saiweier Biotechnology Co., Ltd	GB11128
Miniature hand-held skull drill	Rayward Life Technology Co., Ltd	87001
monofilament suture	Rayward Life Technology Co., Ltd	250-280g
NeuN antibody	Wuhan Saiweier Biotechnology Co., Ltd	GB11138
OCT embedding agent	BIOSHARP	BL557A
Penicillin sodium	Chengdu Kelong Chemical Co., Ltd.	17121709-2
Quick Antigen Retrieval Solution for Frozen Sections	Beyotime Biotechnology Co., LTD	P0090
SD rats	SPF ( Beijing ) Biotechnology Co.,Ltd.	250-280g
Triton X-100	Beyotime Biotechnology Co., LTD	ST795
TTC	Chengdu Kelong Chemical Co., Ltd.	2019030101

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