A Mouse Abdominal Aortic Aneurysm Model by Periadventitial Calcium Chloride and Elastase Infiltration

Summary

This manuscript presents a protocol for establishing a mouse abdominal aortic aneurysm model using calcium chloride and elastase, combining the advantages of previous modeling methods. This model can be utilized to investigate the pathophysiological mechanisms underlying abdominal aortic aneurysms.

Abstract

Abdominal aortic aneurysm (AAA) is a life-threatening disease associated with high mortality rates. It is characterized by the permanent dilation of the abdominal aorta with at least a 50% increase in arterial diameter. Various animal models of AAA have been introduced to mimic the pathophysiological changes and study the underlying mechanisms of AAA. Among these models, the calcium chloride (CaCl₂)- and elastase-induced AAA models are commonly used in mice. However, these methods have certain limitations. Traditional intraluminal porcine pancreatic elastase (PPE) perfusion is associated with high technical difficulty and a high rupture rate, while periadventitial administration of PPE yields inconsistent results. In addition, the CaCl₂-induced AAA model lacks human AAA features, such as atherothrombosis and aneurysm rupture. Therefore, the combined application of CaCl₂ and PPE has been proposed as an approach to enhance success rates and induce greater diameter increases in AAA animal models. This manuscript presents a comprehensive protocol for establishing a mouse AAA model through periaortic infiltration of PPE and CaCl₂ in the infrarenal segment of the abdominal aorta. By following this protocol, we can achieve an AAA formation rate of approximately 90% with technical simplicity and reproducibility. Further ultrasound and histological experiments confirm that this model effectively replicates the morphological and pathological changes observed in human AAA.

Introduction

Abdominal aortic aneurysm (AAA) is defined as a diameter increase of more than 50% or a maximum aortic diameter exceeding 3 cm in the abdominal aorta. This condition poses a significant threat to life, with around a 90% mortality rate upon aneurysm rupture^1,2,3. Currently, open surgical repair and endovascular aortic repair (EVAR) are the only available interventions for AAA patients^4,5,6. However, there is insufficient evidence to support the effectiveness of medical treatments in i....

Protocol

The animal experiment protocol complied with the National Institute of Health Guide for the Care and Use of Laboratory Animals (NIH Pub No. 86/23, 1985) and was approved by the Institutional Animal Care and Use Committee of West China Hospital, Sichuan University (Approval Number 202311300012). Eight to ten-week-old C57/B6J male mice were used for this study. The details of the reagents and equipment used are listed in the Table of Materials.

1. Preoperative preparation<.......

Discussion

Research into the molecular mechanisms of AAA requires a stable animal model. Consequently, numerous AAA animal models have been established since its initial development by Economou et al. in the 1960s²⁹. Among these models, CaCl₂ is frequently employed in rodents due to its cost-effectiveness, technical simplicity, and reliable reproducibility. However, perivascular CaCl₂ infiltration has been shown to be unstable in establishing AAA. Bi et al. and Freestone et al. reported.......

Materials

Name	Company	Catalog Number	Comments
Anesthesia Machine	RWD	R550
Butorphanol	Jiangsu Hengrui Pharmaceutical Co., Ltd	220608BP	1ml: 1mg
C57BL/6JGpt Male Mice	GemPharmatech	N000013
Calcium Chloride	Sigma Aldrich	C4901	100 g
Carprofen	MCE	HY-B1227	100 mg
Chow Diet	Dossy Experimental Animals Co.Ltd
Digital Caliper	Greener	IP54
Ethanol	Jinhe Pharmaceutical Co.Ltd	539682	75%/500 mL
EVG Staining Kit	Solarbio	G1597
GraphPad Prism	Graphpad		Ver 9.0.0
H&E Staining Kit	Servicebio	G1076
Insulin Syringe	BD	2143420
Isoflurane	RWD	R510-22-4	100 mL
Masson Staining Kit	Servicebio	G1006
Normal Saline	Servicebio	G4702	500 mL
Paraformaldehyde	Biosharp	BL539A	4%/500 mL
PBS, 1x	Servicebio	G4202	500 mL
Porcine Pancreatic Elastase	Sigma Aldrich	E1250	100 mg
Povidine Iodine	Yongan Pharmaceutical Co.Ltd		5%/100 mg
Prolene Polypropylene Suture	Ethicon LLC	8709H
Rodent Ultrasound System	Fujifilm	Vevo 3100LT
Stereo Microscope	Olympus	SZ61
Ultrasonic Couplant	Keppler	KL-250	250 g