Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Summary

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

Abstract

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.

Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

Introduction

Traumatic brain injury (TBI) accounts for more than two million hospital visits each year in the United States alone. Mild TBI commonly resulting from car accidents, sporting events, or falls represent approximately 80% of all TBI cases¹. Mild TBI is considered the ‘silent disease’ as patients often experience no overt symptoms in the days and months following the initial insult, but can develop serious TBI-related complications later in life². Moreover, blast-induced mild TBI is prevalent among military service-members, and has been associated with chronic CNS dysfunction^3,....

Protocol

The protocol follows the animal care guidelines of the University of Cincinnati and West Virginia University. All procedures involving animals were approved by the Institutional Animal Care and Use Committees (IACUC), and were performed according to the principles of the Guide for the Care and Use of Laboratory Animals.

1. Installation of the blast TBI setup

1. Acquire all the working parts that are required for the setup, including: shock tube consisting of steel driven- and driver section, polyester membrane, securing bolts, pressure sensors, polyvinyl chloride (PVC) pipe shield to protect peripheral organs, 9.5....

Results

The scalability of the blast wave setup was tested using three different membrane thicknesses, 25.4, 50.8 and 76.2 μm. Peak pressure levels were assessed at the head placement area and the exit of the shock tube apparatus using piezoelectric pressure sensors (see Figure 1 & Figure 2). Peak pressures increase in concordance with membrane thickness at both sensor locations (Figure 3A,B), demonstrating that th.......

Discussion

We present here a preclinical mild TBI model that is cost-effective, easy to set up and execute, and allows for high-throughput, reliable, and reproducible experimental outcomes. This model provides protective shielding to peripheral organs to allow for focused investigation into mild TBI mechanisms while limiting the confounding variables of systemic injury. In contrast, other blast models are known to inflict damage to peripheral organs^2,39,

Materials

Name	Company	Catalog Number	Comments
3/8 SAE High Pressure Hydraulic Hose	Eaton Aeroquip	R2-6-6-36M	Available from Grainger
3/8'' Quick Connect Female Plugs	Karcher	KAR 86410440
3/8'' Quick Connect Male Plugs	Karcher	KAR 86410440
ANY-maze video tracking software	Stoelting Co.	ANY-maze software
Clear Mylar membrane	ePlastics.com	POLYCLR0.003	http://www.eplastics.com/Plastic/Clear_Polyester_Film/POLYCLR0-003; Clear Mylar membrane is sold in various thicknesses. All are sold by vendor listed above.
Compound Slide Table (X2)	Grizzly Industrial	G5757
Deadman Gas Control Ball Valve	Coneraco Inc.	71-502-01	"Apollo", Available from Grainger
Driver and driven section (murine)	own design/production	n/a	For further information please contact the authors
Driver and driven section (rat)	own design/production	n/a	For further information please contact the authors
Ear Muffs	3M	37274	Available from Grainger
Gas Regulator - Hi Flow 3500-600-580	Harris	3003539
Helium Gas	AirGas	HE 300	Tanks are available in various sizes
Inhalation Anesthesia System	VetEquip	901806
Input Module	National Instruments	NI 9223
Isoflurane	Baxter	NDC 10019-360-40	Ordered by veterinarian
Laboratory Timer/Stopwatch	Fisher Scientific	50-550-352
Labview version 12.0	National Instruments		Data Acquistion Software
Magnetic Dial Indicator/Micrometer	Grizzly Industrial	G9849
MATLAB	MathWorks		Software for pressure recording analysis
Oxygen Regulator	Medline	HCS8725M
PC for Data Processing	Dell
Polyvinylchloride Tubing - 25.4 mm	FORMUFIT	P001FGP-WH-40x3
Pressure sensors	PCB Piezotronics	102A05
Receiver USB Chassis	National Instruments	DAQ-9171
Sensor Signal Conditioner	PCB Piezotronics	482C series
Stainless NSF-Rated Mounting Table	Gridmann	GR06-WT2448
T Handle Allen Wrench - 3/16''	S&K	73310