Development of a Multimodal Apparatus to Generate Biomechanically Reproducible Spinal Cord Injuries in Large Animals

Abstract

Rodents are widespread animal models in spinal cord injury (SCI) research. They have contributed to obtaining important information. However, some treatments only tested in rodents did not prove efficient in clinical trials. This is probably a result of significant differences in the physiology, anatomy, and complexity between humans and rodents. To bridge this gap in a better way, a few research groups use pig models for SCI. Here we report the development of an apparatus to perform biomechanically reproducible SCI in large animals, including pigs. We present the iterative process of engineering, starting with a weight-drop system to ultimately produce a spring-load impactor. This device allows a graded combination of a contusion and a compression injury. We further engineered a device to entrap the spinal cord and prevent it from escaping at the moment of the impact. In addition, it provides identical resistance around the cord, thereby, optimizing the inter-animal reproducibility. We also present other tools to straighten the vertebral column and to ease the surgery. Sensors mounted on the impactor provide information to assess the inter-animal reproducibility of the impacts. Further evaluation of the injury strength using neurophysiological recordings, MRI scans, and histology shows consistency between impacts. We conclude that this apparatus provides biomechanically reproducible spinal cord injuries in pigs.

How to generate graded spinal cord injuries in swine – tools and procedures

“…We started with five farm pigs, referred to as SCI-1 to SCI-5. Our previous study showed that an impact of 46 N with our spring-loaded impactor was creating such serious tissue damage that it was likely to be beyond any repair ( Züchner et al, 2019 ). Therefore, as a first trial, we decided to reduce the strength by half.…”

“…In a previous study, we described the development of an impacting apparatus to generate SCIs in large animals ( Züchner et al, 2019 ). We demonstrated that our spring-load impactor generates graded and reproducible impacts on gel pads.…”

“…The development of a spring-load impactor has previously been described elsewhere ( Züchner et al, 2019 ). We now provide a CAD file as ( ).…”

“…All animals underwent an acclimatization period of 5 days minimum in the animal facility. Of note, the procedure described in this article is also based on the experience gained during the generation of acute SCIs in 20 farm pigs ( Züchner et al, 2019 ).…”

“…In a previous work, we reported the development of a new impacting apparatus that is composed of a spring-load impactor, a spinal cord support system and a vertebral column suspension system attached to a pig operating table ( Züchner et al, 2019 ). Because human traumatic SCI often originates from an initial contusion followed by prolonged compression, we designed an impactor that could generate an initial impact followed by static compression.…”