Morphological And Electrophysiological Study Of Spinal Cord Injury In Adult Mammals

There are two parts in the present studies: (1) the axonal regeneration enhanced by fibrin glue (FG)-enwrapped olfactory ensheathing cells (OECs) following spinal cord transection in adult rats and (2) the correlation between the changes of tibia-somatosensory evoked potentials (T-SEPs) and locomotor function of paraplegic hindlimbs following spinal cord hemisection in adult monkeys.Transplantation of OECs into the spinal cord parenchyma has been successfully used to enhance the regrowth of injured spinal nerve fibers in previous studies. However, such transplanting method may result in an extra damage to the spinal cord, such as severe cavitations caused by the micropipettes used and transplanted cell suspensions in huge volume. Furthermore, disconnection of the two stumps is often encountered after spinal cord transection. FG was used in some previous studies as an adhesive agent to repair the central nervous system injury. It does not prevent the neurites from outgrowing or cause any adverse reactions to nerve tissues. In the present study, the intra-slit transplantation of FG enwrapped-OECs was used to see whether OECs survived in situ and migrated into the two stumps after spinal cord transection. The regrowth of transected spinal nerve fibers through the slit and effect of FG on the connection of the two stumps were also investigated.Sixteen adult Sprague-Dawley rats underwent spinal cord transection at Til. Four of these animals received intra-slit transplantation of Hoechst-labeled OECs enwrapped in FG, the others served as control with a similar transplantation of the same volume of FG or DF12-OECs or nothing, respectively. All animals werekilled after a survival period of 2 weeks. The lesioned segments were removed, sectioned horizontally, immunostained with antibodies against neurofllament (NF) or growth associated protein-43 (GAP-43). The survival and migration of transplanted OECs, together with the regrowth of immunoreactive nerve fibers, were observed under a fluorecent microscope or light microscope.Large numbers of transplanted OECs survived in the slit and migrated into both the rostral and caudal stumps. Numerous NF and GAP-43-positive regenerating fibers were detected crossing the slit. Meanwhile, the problem of cavitation formation was much milder. In control group there were only a few NF or GAP-43-immunoreactive fibers in the lesion site. Intra-slit transplantation of either FG-enwraped OECs or FG only resulted in a tight connection of the two stumps. In the animals without any FG transplantation, however, many cavities were found in the lesion, or the two stumps were disconnected. The transplanted OECs enwrapped in FG can survive in the spinal cord lesion and migrate into both the rostral and caudal cord stumps. The regenerating nerve fibers can successfully traverse the lesion along the ensheating glia bridges. FG is conducive to the connection of the two stumps.In the second part, the correlation between the changes of T-SEPs and locomotor function of paraplegic hindlimbs was investigated following spinal cord hemisection in adult monkeys to evaluate the usefulness of T-SEPs in the study of spinal cord injury (SCI) and regeneration.Two adult monkeys (El and E2) received an initial spinal cord hemisection at right LI, and a second hemisection at Til either contralateral (El) or ipsilateral (E2) to the initial lesion 5 months later. T-SEPs was recorded 1 day, 3 and 5 months after the initial surgery, and 1 day after the second hemisection. The change of motor function of the hindlimbs was assessed simultaneously in correlation with the T-SEPs recordings. The initial spinal cord hemisection at right LI resulted in complete paraplegia of the right hind limb in both animals. T-SEPs showed disappearance of N2 and P2 waves in the right side as well as increased N2and ?2 potential latencies (PL) and decreased amplitudes in the left side. When themotor function recovered with time, the lost T-SEPs recurred with increased PL and decreased amplitudes in the right side. The...