Topical Application of Hypothermia in a Porcine Spinal Cord Injury Model

Spinal cord injuries (SCIs) are catastrophic events in humans and animals. They often result in permanent loss of motor, sensory, and autonomic functions caudally from the site of the spinal cord (SC) lesion. The natural history of spontaneous recovery from SC trauma is disappointing and currently available therapeutic interventions fail to operate. Hence further research using bigger experimental animals or primates is necessary. The results of this study performed by the authors in 21 Göttingen-Minnesota-Liběchov female minipigs (3 sham controls, and 18 members of an experimental subgroup) showed that these animals are suitable for SCI research. All mini-pigs survived rather complex experiments carried out in general anaesthesia induced by 5 % thiopental solution administered i.v., maintained by endotracheal inhalation of 1.5 % sevoflurane with O₂ as well as a subsequent 9-week monitoring period. The experimental procedures comprised of L3 laminectomy, SCI inflicted by computer-controlled metallic piston crushing the SC with 8N, 15N, or 18N force. After the SCIs there were 9 minipigs left over during the next 5.5 hours in general anaesthesia, without application of hypothermia, then the surgical wounds were sutured, and the animals were allowed to awaken under supervision. Just 30 min following SCIs was in 6 mini-pigs started with the 5-hour application of 4 °C saline via perfusion chambers placed at the epicenter of the SCI, the chambers were removed, surgical wounds sutured, and animals were allowed to awaken. Just 30 minutes following the SCIs, there was in 3 minipigs started with a 5-hour administration of ≈24 °C saline at the epicentre of the SCIs, and then the perfusion chamber was removed, surgical wounds sutured, and the animals were allowed to awaken. The 5.5-hour local hypothermia and protracted general anaesthesia required monitoring of rectal temperature, and external warming of the minipig, if the temperature dropped below 36 °C. The currently available information on the therapeutic capacity of the method, and all technical aspects of its routine employment, needs validation in further experiments and preclinical trials.