Experimental spinal cord injury models:: protective and repair strategies

While spinal cord injury leads to permanent neurological deficits, experimental data now suggest that a combination of different neuroprotective and reparative measures may eventually help us to decrease the final degree of handicap suffered. Here we review the expression of neurotrophic factors and their receptors in the spinal cord and their regulations in response to different forms of injury. While the spinal cord is less prone than the brain to upregulate these proteins, GDNF and NGF are upregulated in the meninges following weight-drop injury. GFR-alpha1, BDNF, p75 and truncated trkB are also upregulated. Vascular endothelial growth factor (VEGF) is shown to offer neuroprotection if delivered immediately after impact injury. Olfactory ensheathing glial cells express a limited number of neurotrophic molecules, but are able to improve the final outcome of a weight-drop injury following transplantation to the spinal cord. Transplantation of cells containing neurotrophic factors, such as those found in developing dental pulp, offers additional neuroprotective alternatives. Cyst formation is an important clinical problem which can be modeled in rats to further our understanding of factors that cause their development. To monitor sensory deficits and sensory recovery, we have developed fMRI techniques and find that full recovery of hindlimb walking as determined by the BBB scale can occur in the absence of sensory-evoked fMRI signals in the brain. Preliminary data suggest that the implantation of biodegradable tubes containing olfactory ensheathing cells may be beneficial in partial spinal cord injury. Finally, bone marrow stromal cells, proliferated in vitro, survive grafting to the spinal cord and differentiate.