A Murine Model of Cervical Spinal Cord Injury to Study Post-lesional Respiratory Neuroplasticity

Summary

Respiratory failure is the leading cause of death following a cervical spinal cord injury. Having a reproducible, quantifiable, and reliable pre-clinical animal model of respiratory failure induced by a partial cervical injury will help to understand the subsequent respiratory and non-respiratory neuroplasticity and allow testing putative repair strategies.

Abstract

A cervical spinal cord injury induces permanent paralysis, and often leads to respiratory distress. To date, no efficient therapeutics have been developed to improve/ameliorate the respiratory failure following high cervical spinal cord injury (SCI). Here we propose a murine pre-clinical model of high SCI at the cervical 2 (C2) metameric level to study diverse post-lesional respiratory neuroplasticity. The technique consists of a surgical partial injury at the C2 level, which will induce a hemiparalysis of the diaphragm due to a deafferentation of the phrenic motoneurons from the respiratory centers located in the brainstem. The contralateral side of the injury remains intact and allows the animal recovery. Unlike other SCIs which affect the locomotor function (at the thoracic and lumbar level), the respiratory function does not require animal motivation and the quantification of the deficit/recovery can be easily performed (diaphragm and phrenic nerve recordings, whole body ventilation). This pre-clinical C2 SCI model is a powerful, useful, and reliable pre-clinical model to study various respiratory and non-respiratory neuroplasticity events at different levels (molecular to physiology) and to test diverse putative therapeutic strategies which might improve the respiration in SCI patients.

Introduction

Spinal cord trauma is a common injury observed in the human population with dramatic incidences, such as permanent paralysis. However, the severity of the injury depends on the level and the extent of the initial trauma. Respiratory failure is the leading cause of mortality following upper cervical spinal cord injury (SCI)¹. Currently, the only therapeutic treatment is to place the patient under ventilatory assistance. Since few patients can be weaned off the ventilatory assistance², due to spontaneous recovery which occurs with post-lesional delay, the need to develop new innovative non-invasive therapeutics is urgent³. Having a good ....

Protocol

This protocol was approved by the Ethics committee of the RBUCE-UP chair of Excellence (University of Paris Sud, grant agreement No. 246556) and the Université de Versailles Saint-Quentin-en-Yvelines.

1. Preparation of Sterilized Surgical Instruments

1. Clean the surgical instruments with laboratory detergent.
2. Autoclave the instruments prior to surgery.
3. In a surgical session, sterilize the tools by placing the tips in a hot bead sterilizer for 10 min at 180 °C between 2 surgeries.

2. Preparation of Drugs

1. Prepare 2 x 1 ml syringes for pre-anesthetic drugs c....

Results

Extent of Injury

The success and the reproducibility of this particular experimental model are dependent on the experience of each manipulator/surgeon. The subsequent amount of respiratory recovery (phrenic nerve activity and diaphragm activity) following a C2 injury is correlated with the remaining ventrolateral spared white matter²¹. Since the injury is “handmade” and requires some practice from the surgeon, the extent of each injury has to be checked by histologi.......

Discussion

Technical Difficulties of Making the C2 Injury Model

The C2 injury murine model is an interesting tool to study respiratory post-lesional neuroplasticity. However, the steps needed to produce a reproducible and reliable model are numerous and each one could impact on the outcome of the study. For example, during the intubation process, extreme care is to be taken since the orotracheal tube can produce an inflammation of the trachea, which can lead to diverse complications such.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Animal
Male Sprague Dawley Rat	Janvier		225-250 g
Surgical Instruments
Student Dumont #5 forceps	Fine Science Tool	91150-20
Student Standard Pattern Forceps	Fine Science Tool	91100-12
Mayo-Stille Scissors	Fine Science Tool	14013-15	Curved
Student Vannas Spring Scissors	Fine Science Tool	91500-09	Straight
Spring Scissors - 8 mm Blades	Fine Science Tool	15025-10	Straight Blunt/Blunt
Friedman Pearson Rongeur	Fine Science Tool	16121-14	Curved
Dissecting Knife - Fine Tip	Fine Science Tool	10055-12	Straight
Olsen-Hegar Needle Holder	Fine Science Tool	12002-14	Serrated
Weitlaner-Locktite Retractor	Fine Science Tool	17012-11	2x3 Blunt
Absorbable surgical sutures	Centravet	BYO001	Suture size 4-0
Equipment
Hot Bead Steriliser	Fine Science Tool	18000-45
Catheter	Centravet	CAT188	16 G
Laryngoscope
Guide wire
Laryngeal mirror	Centravet	MIR011
Lactated Ringers	Centravet	RIN020
Syringe	Centravet
Needle	Centravet
O2	Air Liquid	I1001M20R2A001
683 RodentT Ventilator 115/230V	Harvard Apparatus	55-0000
Stand-Alone Vaporizer	WPI	EZ-155
Thin line heated bed	WPI	EZ-211
Air canister	WPI	EZ-258
Drugs
Carprofen	Centravet
Rimadyl	Centravet	RIM011
Buprenorphine	Centravet	BUP001
Baytril	Centravet	BAY001
Dexmedetomidine	Centravet	DEX010
Atipamezole	Centravet	ANT201
Betadine solution	Centravet	VET002
Isoflurane	Centravet	VET066