A simple and effective semi-invasive method for inducing local hypothermia in rat spinal cord

Hypothermia has been shown to be an effective treatment for spinal cord injury. Local hypothermia is advantageous because it avoids inducing systemic side effects of general hypothermia while providing the opportunity for greater temperature reduction at the site of injury, which may contribute to increased neuroprotection. We report a new semi-invasive method for inducing local hypothermia in rats' spinal cords. Our method does not require laminectomy or penetration of the dura and is more effective at cooling the cord than transcutaneous approaches. We show that we were successfully able to cool the spinal cord to 30.2±0.3°C for 2 hours with rectal temperature maintained at 37.3±0.3°C after a spinal cord contusion injury. We also validated our method in control rats that received only a laminectomy. Furthermore, this method was able to reliably cool and rewarm the cord at a steady rate (Δ5.5°C in 30 min, or 0.2°C/min). Future work will include validating long-term functional improvements of injured rats after treatment and to apply local cooling to other spinal cord injury models, such as compression injuries.