A Rat Carotid Balloon Injury Model to Test Anti-vascular Remodeling Therapeutics

Summary

The rat carotid balloon injury model described below allows researchers to evaluate drugs or therapeutics that negate injury-induced arterial hyperplasia. Detailed pre-surgical preparation, surgical procedure, and post-surgical cares of the animal are described.

Abstract

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is also a valuable model system to test, and to evaluate therapeutics and drugs that negate maladaptive remodeling in the vessel. The injury, or barotrauma, in the vessel lumen caused by an inflated balloon via an inserted catheter induces subsequent neointimal growth, often leading to hyperplasia or thickening of the vessel wall that narrows, or obstructs the lumen. The method described here is sufficiently sensitive, and the results can be obtained in relatively short time (2 weeks after the surgery). The efficacy of the drug or therapeutic against the induced-remodeling can be evaluated either by the post-mortem pathological and histomorphological analysis, or by ultrasound sonography in live animals. In addition, this model system has also been used to determine the therapeutic window or the time course of the administered drug. These studies can leadto the development of a better administrative strategy and a better therapeutic outcome. The procedure described here provides a tool for translational studies that bring drug and therapeutic candidates from bench research to clinical applications.

Introduction

Angioplasty is an endovascular procedure used to widen the narrowed or obstructed arteries resultant from pathological conditions such as atherosclerosis. One common complication of angioplasty is the post-operational neointimal hyperplasia, or restenosis, which occurs owing to surgical injuries and the subsequent inflammation-induced vascular remodeling. These conditions lead to proliferation of vascular smooth cells, and multiple pathophysiological consequences^1-3. Neointimal hyperplasia re-thickens the vessel, and occurs in up to 60% post-angioplasty patients within the first year. Therefore, restenosis is a major setback of the widely used angioplasty p....

Protocol

NOTE: the use of rat balloon injury model and associated procedures including injection of recombinant sRAGE and ultrasound sonographic studies have been approved by the Animal Care and Use Committee (ACUC) of National Institute on Aging, NIH.

1. Pre-surgery Preparations

1. Instrument, Surgical Platform, and Personal Protection Equipment.
   1. See Materials and Equipment's Table for all the surgical instruments and reagents used in this procedure. Autoclave all surgical instruments prior to surgical procedure.
      NOTE: For multiple surgeries performed at the same day, use a pre-heat....

Results

Two weeks after the balloon injury, the rat is euthanized and the carotid arteries are isolated for histo-morphological analysis. Both operated left carotid artery and un-operated right artery are cross-sectioned, processed, and paraffin-embedded. The paraffin samples are then further thin-sectioned, and stained with hematoxylin-eosin (H & E). Histo-morphological analyses are performed using a digital imaging analysis system. The details of artery harvest and histo-morphological analy.......

Discussion

There have been two methods used to inflate the balloon in order to generate the injury that removes the mural endothelium in the carotid arterial lumen. One is to fill the attached syringe with liquid²⁰, and the other is to use air pressure²¹. We prefer to use liquid-filled syringe because the exact liquid volume (0.02 ml) will be used for each procedure. This renders a precise and reproducible inflation of the balloon, leading to a similar level of injury in each animal undergoing the procedure. U.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
2 F Fogarty balloon embolectomy catheter	Edwards Lifesciences
Standard scalpel	Fine Science Tools
Small  curved forceps (Large radius Dumont#7shanks curved)	Fine Science Tools
Large, medium and small micro-scissors	Roboz
Needles (20 G)	TycoHealthcare
Micro-surgery forceps with micro-blunted atraumatic tips	Fine Science Tools
Atraumatic straight small arterial clamps	Fine Science Tools
Retractor  with maximum spread 5.5 cm long blunt teeth	Fine Science Tools
Silk suture (4.0 and  6.0 )	Fine Science Tools
Syringe (1.0 ml)	BD
Curity gauze sponges	AllegroMedical
Cotton tip applicators sterile and non-sterile	Puritan Medical Products
Compact hot bead sterilizer	Fine Science Tools
Self-regulating heating pad	Fine Science Tools
ADS200 anesthesia system/ventilator	Paragon Medical
Isoflurane (forane), liquid form	Baxter
Sodium chloride 0.9% (Saline)	Hospira
Buprenex (buprenorphine)	Reckitt Benckiser Healthcare (UK) Ltd.
70% alcohol	Fisher
1:10 Betadine	Fisher