A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Summary

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Abstract

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

Introduction

The number of patients experiencing ischemic diseases due to atherosclerosis is increasing worldwide¹. Despite the current advances in medical and surgical therapies for cardiovascular diseases, ischemic heart diseases, such as myocardial infarction, remain a major cause of morbidity and mortality². Furthermore, peripheral arterial diseases characterized by reduced blood flow to the limbs induces critical limb ischemia, wherein approximately 40% of the patients lose their legs within 6 months of diagnosis, and the mortality rate is up to 20%³.

Revascularization surgerie....

Protocol

NOTE: All the surgical procedures performed on animals should be carried out in accordance with the Guide for the Care and Use of Laboratory Animals (www.nap.edu/catalog/5140.html) or other appropriate ethical guidelines. Protocols should be approved by the animal welfare committee at the appropriate institution before proceeding.

1. Preparation of animals

1. Purchase male Japanese white rabbits (or rabbits with equivalent body size) weighing 2.7–3.0 kg.
2. Acclimate the rabbits for 1 week in a 12 hour light–dark cycle and feed a regular rabbit chow diet before the procedure.

2. A....

Results

Figure 1A shows a representative image of successful intimal hyperplasia at 2 weeks after venous interposition surgery (upper panel). The lower panel shows the therapeutic effects of microRNA-145-loaded poly(lactic-co-glycolic acid) nanoparticles that attenuated the intimal hyperplasia (lower panel). Figure 1B shows the comparison of intimal hyperplasia between the control group using phosphate buffered saline control (PBS), control microRNA (Cont-miR), and micr.......

Discussion

The present protocol is designed to provide an experimental platform to test various molecular or genetic interventions for VSMCs to control the phenotype from the proliferative to the contractile state and subsequently attenuate the progression of venous intimal hyperplasia in vivo. Using this model, we successfully prepared intimal hyperplasia at 2 weeks after surgery (Figure 1A) and indicated the therapeutic potential of microRNA-145 to control the VSMC phenotype²⁶.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
10% Povidone-iodine solution	Nakakita	872612	Surgical expendables
2-0 VICRYL Plus	Johnson and Johnson	VCP316H	Surgical expendables
4-0 Silk suture	Alfresa pharma	GA04SB	Surgical expendables
8-0 polypropylene suture	Ethicon	8741H	Surgical expendables
Cefazorin sodium	Nichi-Iko Pharmaceutical	6132401D3196	Antibiotics
Fogarty Catheter (2Fr)	Edwards Lifesciences LLC	E-060-2F	Surgical expendables
Heparin	Nipro	873334	Anticoagulant
Intravenous catheter (20G)	Terumo	SR-OT2051C	Surgical expendables
Isoflurane	Fujifilm	095-06573	Anesthesia
Lidocaine hydrochloride	MP Biomedicals	193917	Anesthesia
Pentobarbital sodium	Tokyo Chemical Industry	P0776	Anesthesia