A hemi-contusive cervical spinal cord injury model with displacement control in rats

The present study is aimed to develop a hemi-contusive injury model of cervical spinal cord injury (SCI) with displacement control at a higher contusive speed, and demonstrates unilateral cord tissue loss and ipsilateral forelimbs impairment. Ten adult male Sprague Dawley rats were subjected to the hemi-contusion SCI. 1.5-mm-indiameter cylinder impactor 22.5 degrees laterally and 1.4 mm off-set was driven to compress unilateral C5 cord 2.2 mm at 600 mm/s. Forelimb functional assessments, including Montoya staircase task, cylinder rearing test and grooming test, were performed before and after injury. At 12 weeks post-injury, spared gray, white matter, and lesion area were calculated on a series of transverse cord sections. Average contusive displacement, speed and compressive force were 2.196 +/- 0.003 mm, 598.5 +/- 1.4 mm/s and 1.462 +/- 0.117 N respectively. The unilateral contusive injury resulted in ipsilateral tissue loss of anterior horn and lateral funiculus, while the ipsilateral dorsal funiculus and dorsal horn and contralateral cord were intact. In epicenter, average lesion area is 1.56 +/- 0.30 mm(2), and percentage of white and gray matter area accounted for 40 +/- 14% and 41 +/- 12% respectively. The ipsilateral forelimb exhibited sustained impairments in ipsilateral forelimb motor function after injury. The present study showed that the hemicontusive SCI model with displacement control achieved consistent contusive displacement and force at a higher speed. The spinal cord tissue loss was confined within ipsilateral cord. The ipsilateral forelimb exhibited sustained impairments in motor function after injury while contralateral forelimb was intact. Our study provides an alternative method to establish a contusive SCI model for neuroprotective strategies.