Traumatic Peripheral Nerve Injury in Mice

Summary

The present protocol describes traumatic peripheral nerve injuries (TPNIs), including precisely calibrated crush, strictly aligned and misaligned laceration, as well as grafted and non-grafted gaps of the sciatic nerve in mice. Custom-designed sensors are developed to gauge nerve trauma, induced with commonly available tools to ensure reproducible post-TPNI outcomes.

Abstract

Traumatic peripheral nerve injury (TPNI) is a common cause of morbidity following orthopedic trauma. Reproducible and precise methods of injuring nerve and denervating muscle have long been a goal in musculoskeletal research. Many traumatically injured limbs have nerve trauma that defines the long-term patient outcome. Over several years, precise methods of producing microsurgical nerve injuries have been developed, including crush, lacerations, and nerve-gap grafting, allowing for reproducible outcome assessments. Moreover, newer methods are created for calibrated crush injuries that offer clinically relevant correlations with outcomes used to assess human patients. The principles of minimal manipulation to ensure low variability in nerve injury allow for adding still more associated tissue injuries into these models. This includes direct muscle crush and other components of limb injury. Finally, atrophy assessment and precise analysis of behavioral outcomes make these methods a complete package for studying musculoskeletal trauma that realistically incorporates all the elements of human traumatic limb injury.

Introduction

Traumatic peripheral nerve injury (TPNI) is a common cause of morbidity after orthopedic trauma^1,2,3. Yearly, approximately 3% of trauma patients suffer nerve injury^1,4, at an incidence of 3,50,000 cases⁵, resulting in 50,000 surgical repairs⁶. TPNIs occur in a wide range of severity, and the functional recovery directly depends on the type and severity of these injuries^7,8,9. L....

Protocol

The experimental design and animal protocols were approved by the Institutional Animal Care and Use Committee (IACUC) at Penn State University College of Medicine. Adult C57BL/6J male mice, 10-week-old, weighing 20-25 g, were used for the studies. Animals were housed at the animal facility under sterile animal management conditions, and they were acclimatized at least 5 days before conducting the studies.

1. Animal preparation

1. Anesthetize the animals deeply using a cocktail of ketamine (100 mg/kg) and xylazine (10 mg/kg) via intraperitoneal injection using a 26 G needle.
2. Shave the animals'....

Results

The custom-made digital pressure sensor device (Figure 1D) operates by detecting the change in resistance of the FSR when a force is applied. This device senses and records the most modest pressure amounts applied to it with a response time of <5 µs, a sampling rate of 20 Hz, and a pressure range of 2.5-25 lbs³¹. The differences in the forceps (Figure 1C) induced SNCI (Figure 1A,B) pressur.......

Discussion

The history of TPNI research stretches over several decades^11,12. Early experiments with dogs and larger species established the importance of animal models in the study of TPNI outcomes^36,37,38. Over time, these models have moved into smaller rodents, with their established and commonly used validated outcomes measures^39,

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Alcohol prep	COVIDIEN	5110
Buprenorphine	ZooPharm	BSRLAB0.5-211706
C57BL/6J	Jackson Laboratories, Bar Harbor	N/A
Cotton tipped applicators	Puritan	25-8062WC
Dissecting scissor	ASSI	ASSI.SDC18R8
Fibrin glue-TISSEEL	Baxter	1501263
Force Sensitive Resistor (FSR)	N/A	FlexiForce A301
Forceps	FST-Dumont	5SF Inox, 11252-00
GraphPad Prism	GraphPad Software Inc.	Version 8.4.3.
Homeothermic heating pad	Kent Scientific	RJ1675
Ketamine/Ketaved	VEDCO	VED1220
Microsurgical Forceps	Miltex Premium instruments	BL1901
Ophthalmic lubricant ointment	Akorn Animal Health	NDC 59399-162-35
Petri dish	VWR	25384-092
Phosphate-buffered saline	Gibco	14190-144
Povidone iodine	Solimo	L0017765SA
Precision pinch pressure sensor device	Custom made	N/A
Scissor	Miltex Premium	21-536
Stereo zoom binocular microscope	World Precision Instruments	Model PZMIII
Sterile gloves	Cardinal Health	9L19E511
Surgical staples	3M-Precise	DS-25
Surgical Tape	3M-Microphore	1530-0
Sutures	Ethicon	BV130-5
Syringe	BD syringe	309597
Trimmer	Philips Electronics	MG3750
Xylazine/Anased	Akorn Animal Health, Inc.	VAM4811