Induction of Complete Transection-Type Spinal Cord Injury in Mice

Summary

This protocol describes how to create a precise laminectomy for induction of stable transection-type spinal cord injury in the mouse model, with minimal collateral damage for spinal cord injury research.

Abstract

Spinal cord injury (SCI) largely leads to irreversible and permanent loss of function, most commonly as a result of trauma. Several treatment options, such as cell transplantation methods, are being researched to overcome the debilitating disabilities arising from SCI. Most pre-clinical animal trials are conducted in rodent models of SCI. While rat models of SCI have been widely used, mouse models have received less attention, even though mouse models can have significant advantages over rat models. The small size of mice equates to lower animal maintenance costs than for rats, and the availability of numerous transgenic mouse models is advantageous for many types of studies. Inducing repeatable and precise injury in the animals is the primary challenge for SCI research, which in small rodents requires high-precision surgery. The transection-type injury model has been a commonly used injury model over the last decade for transplantation-based therapeutic research, however a standardized method for inducing a complete transection-type injury in mice does not exist. We have developed a surgical protocol for inducing a complete transection type injury in C57BL/6 mice at thoracic vertebral level 10 (T10). The procedure uses a small tip drill instead of rongeurs to precisely remove the lamina, after which a thin blade with rounded cutting edge is used to induce the spinal cord transection. This method leads to reproducible transection-type injury in small rodents with minimal collateral muscle and bone damage and therefore minimizes confounding factors, specifically where behavioral functional outcomes are analyzed.

Introduction

Spinal cord injury (SCI) is a complex medical problem that results in drastic changes in health and lifestyle. There is no cure for SCI, and the pathophysiology of SCI is not thoroughly understood. Animal SCI models, in particular rodent models, offer an invaluable tool for trialing new treatments, and have been used to explore SCI for decades. To date, over 72% of pre-clinical SCI studies have employed rat models, as compared to a mere 16% that have used mice¹. Although rats, due to their larger size and tendency to form cavities akin to human SCIs, have traditionally been the preferred model animals for studying novel therapeutic approaches, ....

Protocol

All procedures were carried out with the approval of the Griffith University Animal Ethics Committee (ESK/04/16 AEC and MSC/04/18 AEC) under the guidelines of the National Health and Medical Research Council of Australia.

1. Animal set-up procedure for the surgery

1. Anesthetize and stabilize the animal.
   1. Use 8–10-week old female C57BL/6 mice. Use 5% isoflurane in 1 L/min oxygen for induction of anesthesia. For maintenance of anesthesia, use 1.5–2% isoflurane in.......

Discussion

This method induces a complete transection type injury at the T10 vertebral level in mice, which results in complete paraplegia of the animal, below the level of injury. Overall, this method results in minimal bleeding, negligible collateral damage and a stable, reproducible injury. As compared to previously published methods of transection without laminectomy¹⁰, this method offers the benefits in terms of direct visualization without manipulating the curvature of the spine, better control over co.......

Materials

Name	Company	Catalog Number	Comments
Baytril injectable 50 mg/mL, 50 mL	Provet	BAYT I	Post-operative care drug
Betadine 500 mL	Provet	BETA AS	Consumable
Castroviejo needle holder, locking	ProSciTech	T149C	Reusable
Ceramic zirconia blade, round with sharp sides, single edge, angled	ProSciTech	TXD101A-X	Reusable
Cotton swabs (5pcs)	Multigate	21-893	Consumable
Dremel Micro	DREMEL	8050-N/18	Cordless rotary tool
Dressing forceps fine	Multigate	06-306	Single use disposable
Drill bits	Kemmer Präzision	SM 32 M 0550 070	Reusable
Dumont #7b forceps	Fine Science Tools	11270-20	Reusable
Dumont tweezers, style 5	ProSciTech	T05-822	Reusable
Fur trimmer	WAHL	WA9884-312	Zero Overlap Hair Trimmer
Iris scissors, Ti, sharp tips, straight, 90mm	ProSciTech	TY-3032	Reusable
Isoflurane isothesia NXT 250	Provet	ISOF 00 HS	Anaesthetic agent
Colibri Retractor - 4cm	Fine Science Tools	17000-04	Reusable
Scalpel handle	ProSciTech	T133	Reusable
Signature latex surgical gloves size 7.5	Medline	MSG5475	Consumable
Sodium Chloride 0.9%	STS	PHA19042005	Consumable
Sterile Dressing Pack	Multigate	08-709	Single use disposable
Sterile Fluid Impervious Drape 60x60 cm	Multigate	29-220	Single use disposable
Surgical spirit 100 mL	Provet	# SURG SP	Consumable
Suture Material - SILK BLK 45CM 5/0 FS-2	Johnson & Johnson Medical	682G	Silk Suture
Suture Material - Vicryl 70CM 5-0 S/A FS-2	Johnson & Johnson Medical	VCP421H	Vicryl Suture
Temgesic 0.3 mg in 1 mL, x 5 ampoules (class S8 drug)	Provet	TEMG I	Post-operative care drug