A Model for Encephalomyosynangiosis Treatment after Middle Cerebral Artery Occlusion-Induced Stroke in Mice

Summary

The protocol aims to provide methods for encephalomyosynangiosis-grafting of a vascular temporalis muscle flap on the pial surface of ischemic brain tissue-for the treatment of non-moyamoya acute ischemic stroke. The approach's efficacy in increasing angiogenesis is evaluated using a transient middle cerebral artery occlusion model in mice.

Abstract

There is no effective treatment available for most patients suffering with ischemic stroke, making development of novel therapeutics imperative. The brain's ability to self-heal after ischemic stroke is limited by inadequate blood supply in the impacted area. Encephalomyosynangiosis (EMS) is a neurosurgical procedure that achieves angiogenesis in patients with moyamoya disease. It involves craniotomy with placement of a vascular temporalis muscle graft on the ischemic brain surface. EMS has never been studied in the setting of acute ischemic stroke in mice. The hypothesis driving this study is that EMS enhances cerebral angiogenesis at the cortical surface surrounding the muscle graft. The protocol shown here describes the procedure and provides initial data supporting the feasibility and efficacy of the EMS approach. In this protocol, after 60 min of transient middle cerebral artery occlusion (MCAo), mice were randomized to either MCAo or MCAo + EMS treatment. The EMS was performed 3-4 h after occlusion. The mice were sacrificed 7 or 21 days after MCAo or MCAo + EMS treatment. Temporalis graft viability was measured using nicotinamide adenine dinucleotide reduced-tetrazolium reductase assay. A mouse angiogenesis array quantified angiogenic and neuromodulating protein expression. Immunohistochemistry was used to visualize graft bonding with brain cortex and change in vessel density. The preliminary data here suggest that grafted muscle remained viable 21 days after EMS. Immunostaining showed successful graft implantation and increase in vessel density near the muscle graft, indicating increased angiogenesis. Data show that EMS increases fibroblast growth factor (FGF) and decreases osteopontin levels after stroke. Additionally, EMS after stroke did not increase mortality suggesting that protocol is safe and reliable. This novel procedure is effective and well-tolerated and has the potential to provide information of novel interventions for enhanced angiogenesis after acute ischemic stroke.

Introduction

Ischemic stroke is an acute neurovascular injury with devastating chronic sequelae. Most of the stroke survivors, 650,000 per year, in the US suffer from permanent functional disability¹. None of the available treatments confer neuroprotection and functional recovery after the acute phase of ischemic stroke. After an acute ischemic stroke, both direct and collateral blood supplies are diminished which leads to dysfunction of brain cells and networks, resulting in sudden neurological deficits^2,3. Restoration of blood supply to the ischemic region remains the foremost goal of stroke thera....

Protocol

All experiments were approved by the Institutional Animal Care and Use Committee of UConn Health and conducted in accordance with US guidelines. The following protocol should work in any species or strain of rodent. Here, 8- to 12-week-old, age- and weight-matched C57BL/6 wild-type male mice were used. Mice were fed standard chow diet and water ad libitum. Standard housing conditions were maintained at 72.3 °F and 30%-70% relative humidity with a 12 h light/dark cycle.

Discussion

This protocol describes a successful EMS procedure in a mouse model of MCAo-induced stroke. The data show that grafted tissue remains viable and can form bonds with brain cortex long after EMS surgery. These findings support the rationale for using a cerebral muscle graft to gradually develop a richly vascular trophic environment at the site of stroke. EMS is a promising therapy for potentially repairing infarcted cerebral tissue in the same environment.

The critical steps of the protocol incl.......

Materials

Name	Company	Catalog Number	Comments
6-0 monocryl suture	Ethilon	697G
70% ethanol to sanitize operating surface	Walgreen
Bupivacaine 0.25% solution	Midwest Vet
Clamps for tissue retraction	Roboz
Doccal suture with Nylon coating	Doccal corporation Sharon MA	602145PK10Re
Electric heating pad for operating surface
Isoflurane anesthesia	Piramal Critical Care Inc
Isoflurane delivery apparatus	--B6Surgivet (Isotech 4)
Micro drill	Harvard Apparatus
Microdissecting tweezers, curved x2	Piramal Critical Care Inc
mouse angiogenesis panel arrat	R& D biotech	ARY015
Needle driver	Ethilon
Ointment for eye protection	walgreen
Operating microscope	Olympus
Operating surface	Olympus
Povidone iodine solution	walgreen
Rectal thermometer	world precison instrument
Saline or 70% ethanol for irrigation	walgreen
Small electric razor to shave operative site	generic
Surgical scissors	Roboz