A simple, inexpensive and easily reproducible model of spinal cord injury in mice: morphological and functional assessment.

Spinal cord injury (SCI) causes motor and sensory deficits that impair functional performance, and significantly impacts life expectancy and quality. Animal models provide a good opportunity to test therapeutic strategies in vivo. C57BL/6 mice were subjected to laminectomy at T9 and compression with a vascular clip (30g force, 1min). Two groups were analyzed: injured group (SCI, n=33) and laminectomy only (Sham, n=15). Locomotor behavior (Basso mouse scale-BMS and global mobility) was assessed weekly. Morphological analyses were performed by LM and EM. The Sham group did not show any morphofunctional alteration. All SCI animals showed flaccid paralysis 24h after injury, with subsequent improvement. The BMS score of the SCI group improved until the intermediate phase (2.037+/-1.198); the Sham animals maintained the highest BMS score (8.981+/-0.056), p<0.001 during the entire time. The locomotor speed was slower in the SCI animals (5.581+/-0.871) than in the Sham animals (15.80+/-1.166), p<0.001. Morphological analysis of the SCI group showed, in the acute phase, edema, hemorrhage, multiple cavities, fiber degeneration, cell death and demyelination. In the chronic phase we observed glial scarring, neuron death, and remyelination of spared axons by oligodendrocytes and Schwann cells. In conclusion, we established a simple, reliable, and inexpensive clip compression model in mice, with functional and morphological reproducibility and good validity. The availability of producing reliable injuries with appropriate outcome measures represents great potential for studies involving cellular mechanisms of primary injury and repair after traumatic SCI.