Validation of a Precise Impactor in a Rodent Cervical Spinal Cord Injury Hemi-Contusion Model

• Published in: BioMed 2024-11, Vol.4 (4), p.524-540
• Main Authors: Castillo, Jose A., Le, Michael Nhien, Pivetti, Christopher, Jackson, Jordan E., Kulubya, Edwin, Paxton, Zachary, Reed, Camille, Soufi, Khadija, Rafi, Arash Ghaffari, Martin, Allan, Price, Richard, Kim, Kee, Farmer, Diana, Wang, Aijun, Russo, Rachel
• Format: Article
• Language: English
• Subjects: cervical spinal cord injuries; pre-clinical model; precise impactor; spinal cord contusion
• ISSN: 2673-8430; 2673-8430
• DOI: 10.3390/biomed4040039

Background: Cervical spinal cord injuries (SCIs) are the most common type of human SCI. Although various animal SCI contusion models have been developed to mirror human pathology, few have described cervical-level injuries. This study aims to validate and establish optimal impact parameters to produce consistent incomplete cervical SCIs for testing novel therapies. Methods: Using a precise impactor, 3 cervical spinal cord hemi-contusions of varying severities were induced by modifying penetration depths and controlling dwell times. Penetration depths of 2.11 mm (n = 4), 2.24 mm (n = 4), and 2.36 mm (n = 3) were used with a dwell time of 0.05 s to create mild, moderate, and severe injuries. Behavioral assessments in weeks 1, 2, 5, and 8 included grooming test, forelimb asymmetry test, and the Irvine, Beatties, and Bresnahan forelimb scale (IBB). After 8 weeks, rats were euthanized, and spinal cord histology was performed. Results: Within each group, animals exhibited consistent motor deficits and functional recovery. Mean IBB scores varied significantly between each group at week 8 (p < 0.0001). Ipsilateral forelimb usage significantly improved throughout the study period in the mild (2.11 mm) and moderate (2.24 mm) groups, while the severely (2.36 mm) injured group continued to exhibit 100% asymmetrical forelimb usage. Conclusions: This study demonstrates that a precise impactor can create reproducible models of incomplete cervical SCIs. A penetration depth of 2.24 mm resulted in moderate injury with significant motor deficits that slowly improved over time, permitting future therapeutic studies in functional recovery.