This study investigated the neuroprotective efficacy of local hypothermia in a minipig model of spinal cord injury (SCI) induced by a computer-controlled impactor device. The tissue integrity observed at the injury epicenter, and up to 3 cm cranially and caudally from the lesion site correlated with motor function. A computer-controlled device produced contusion lesions at L3 level with two different degrees of tissue sparing, depending upon pre-set impact parameters (8N- and 15N-force impact). Hypothermia with cold (4°C) saline or Dulbecco's modified Eagle's medium (DMEM)/F12 culture medium was applied 30 min after SCI (for 5 h) via a perfusion chamber (flow 2 ml/min). After saline hypothermia, the 8N-SCI group achieved faster recovery of hind limb function and the ability to walk from one to three steps at nine weeks in comparison with non-treated animals. Such improvements were not observed in saline-treated animals subjected to more severe 15N-SCI or in the group treated with DMEM/F12 medium. It was demonstrated that the tissue preservation in the cranial and caudal segments immediately adjacent to the lesion, and neurofilament protection in the lateral columns may be essential for modulation of the key spinal microcircuits leading to a functional outcome. Tissue sparing observed only in the caudal sections, even though significant, was not sufficient for functional improvement in the 15N-SCI model.

According to previous opinion, the derivation of neurons and glia from the central canal (CC) lining of the spinal cord in rodents should occur in the embryonic period. Reports of the mitotic activity observed in the lining during postnatal development have often been contradictory, and proliferation was ascribed to the generation of ependymocytes, which are necessary for the elongation of CC walls. Our study quantifies the intensity of proliferation and determines the cellularity of the CC lining in reference to lumbar spinal segment L4 during the postnatal development of rats. The presence of dividing cells peaks in the CC lining on postnatal day 8 (P8), with division occurring in 19.2% ± 3.2% of cells. In adult rats, 3.6% ± 0.9% of cells still proliferate, whereas, in mice, 10.3% ± 2.3% of cells at P8 and only 0.6% ± 0.2% of cells in the CC lining in adulthood are proliferating. In the rat, the length of the cell cycle increases from 100.3 ± 35.7 hours at P1 to 401.4 ± 80.6 hours at P43, with a sudden extension between P15 and P22. Despite the intensive proliferation, the total cellularity of the CC lining at the L4 spinal segment significantly descended in from P8 to P15. According to our calculations, the estimated cellularity was significantly higher compared with the measured cellularity of the CC lining at P15. Our results indicate that CC lining serves as a source of cells beyond ependymal cells during the first postnatal weeks of the rat. J. Comp. Neurol. 525:693-707, 2017. © 2016 Wiley Periodicals, Inc.

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