Remotely Triggered LAD Occlusion Using a Balloon Catheter in Spontaneously Breathing Mice

Summary

This article presents a unique closed-chest technique for inducing myocardial ischemia-reperfusion injury (IRI) in mice. The presented method allows mice to breathe spontaneously while remotely inducing myocardial ischemia. This provides access to the animal for studying the dynamic processes of ischemia and reperfusion in situ and in real-time via noninvasive imaging.

Abstract

Acute myocardial infarction (AMI) is a prevalent and high-mortality cardiovascular condition. Despite advancements in revascularization strategies for AMI, it frequently leads to myocardial ischemia-reperfusion injury (IRI), amplifying cardiac damage. Murine models serve as vital tools for investigating both acute injury and chronic myocardial remodeling in vivo. This study presents a unique closed-chest technique for remotely inducing myocardial IRI in mice, enabling the investigation of the very early phase of occlusion and reperfusion using in-vivo imaging such as MRI or PET. The protocol utilizes a remote occlusion method, allowing precise control over ischemia initiation after chest closure. It reduces surgical trauma, enables spontaneous breathing, and enhances experimental consistency. What sets this technique apart is its potential for simultaneous noninvasive imaging, including ultrasound and magnetic resonance imaging (MRI), during occlusion and reperfusion events. It offers a unique opportunity to analyze tissue responses in almost real-time, providing critical insights into processes during ischemia and reperfusion. Extensive systematic testing of this innovative approach was conducted, measuring cardiac necrosis markers for infarction, assessing the area at risk using contrast-enhanced MRI, and staining infarcts at the scar maturation stage. Through these investigations, emphasis was placed on the value of the proposed tool in advancing research approaches to myocardial ischemia-reperfusion injury and accelerating the development of targeted interventions. Preliminary findings demonstrating the feasibility of combining the proposed innovative experimental protocol with noninvasive imaging techniques are presented herein. These initial results highlight the benefit of utilizing the purpose-built animal cradle to remotely induce myocardial ischemia while simultaneously conducting MRI scans.

Introduction

Acute myocardial infarction (AMI), a prevalent global cardiovascular condition, is associated with high mortality rates and morbidity¹. Despite technological advancements that enabled early and effective revascularization strategies for AMI patients, patients still experience myocardial ischemia-reperfusion injury (IRI) following these interventions². Therefore, understanding the fundamental mechanisms and formulating approaches to mitigate IRI is crucial. IRI represents a complex pathophysiological state involving a multitude of intricate biological processes. These encompass regulated cell death, oxidative stress respo....

Protocol

This animal protocol was approved by and is in accordance with the guidelines and regulations set forth by the Ethical Committee for Animal Experimentation (ECD) at The Catholic University of Leuven. All policies developed by the local ECD follow the regulations of the European Union concerning the welfare of laboratory animals as declared in Directive 2010/63/EU. All tests described below have been performed on 8-12 week-old (body weight = 20-23 g) male C57BL/6 mice. The acute experiments represent animals that were imm.......

Discussion

The novel remote occlusion technique introduced in this study offers a unique platform to advance research in the field of ischemia-reperfusion injury modeling by avoiding the need for direct vessel manipulation during the initial surgery and allowing simultaneous multi-modal imaging of the early reperfused myocardium. Comprehensive characterization, including troponin-I measurements, LGE contrast MRI, TTC, and SR staining, shows that the proposed technique is equivalent to the current golden standard (i.e., ope.......

Materials

Name	Company	Catalog Number	Comments
2-0 silk suture	Sharpoint Products	DC-2515N
5-0 polypropylene suture	Ethicon	8710H
7-0 polypropylene suture	Ethicon	8206H
ACCLARENT Balloon Inflation Device	Johnson&Johnson MedTech	BID30
Acepromazine	Kela
BD Vialon 18 G	BD	381347
BD Vialon 20 G	BD	381334
Betadine Solution	Purdue Pharma	25655-41-8
Buprenorphine (Buprenex Injectable)	Reckitt Benkiser Healthcare	NDC 12496-0757-1
Carp Zoom Styl Knijplood 2.1 g (lead fishing weights)	Visdeal.nl
Dumont #3 Forceps	Fine Science Tools	11231-30
Dumont #5 Forceps	Fine Science Tools	11251-30
Fine Scissors	Fine Science Tools	14040-10
Fucidine gel	Leo Pharma
Isoflurane	Abbott	NDC 5260-04-05
KD Mouse/Rat Eye Speculum	World Precision Instruments	501897
KD mouse/rat eye speculum	World Precision Instruments	501897
Ketamine	Dechra
Light source	Zeiss	KL 1500 LCD
MRI system	Bruker BioSpin, Ettlingen, Germany	BioSpec 70/30
NatriumChloride 0.9%	Baxter
Nocturnal Infrared Heat Lamp	Zoo Med Laboratories, Inc.	RS-75
ParaVision software	Bruker BioSpin	version 6.0.1
polyethylene tubing PE-10	SAI Infusion technologies	PE-10
polyethylene tubing PE-50	SAI Infusion technologies	PE-50
remote IRI tool (PMMA)	homemade
Rodent Surgical Monitor	Indus instruments
Segment v4.0	Medviso, segment.heiberg.se	R12067
Self-gated gradient echo sequence	Bruker BioSpin, Ettlingen, Germany	IntraGate, ParaVision 6.0.1
Slim Elongated Needle Holder	Fine Science Tools	12005-15
Sure-Seal Mouse/Rat Induction Chamber	World Precision Instruments	EZ-178
Tubing Connectors, Poly, Y Shape	Westlab	072025-0001
Ultraverse 035 PTA Dilatation Catheter: 5mm x 40mm, 17 ATM RBP balloon on 130 cm long catheter	Bard Peripheral Vascular, Inc.	00801741092671
Veet (depilatory creme)	Reckitt Benkiser Healthcare
Ventilator, MiniVent Model 845	Hugo Sachs	73-0043
Vidisic	BAUSCH & LOMB PHARMA	685313
Xylazine	Bayer