Acute Spinal Cord Injury In Vitro: Insight into Basic Mechanisms

Spinal injury is produced by traumatic and nontraumatic causes that often induce long-term disability. In order to limit tissue damage and functional impairment, it is important to intervene at an early stage after the primary insult to restrain damage extension. This objective is difficult to achieve since the mechanisms underlying cell death in the spinal cord are complex and incompletely understood. We discuss how to set up a simple in vitro preparation of the neonatal rat spinal cord that retains full activity of locomotor networks and allows detailed investigations into the elementary pathological processes after inducing an experimental injury in vitro. We report different methods for producing an in vitro lesion: one is based on the excitotoxic action of the glutamate analogue kainate; one on the application of dysmetabolic conditions comprising hypoxia, aglycemia, and free oxygen radicals; and finally one due to the combination of both methods. Furthermore, the toxic insult can be applied to the entire in vitro preparation or to a few spinal segments isolated from the rest of the spinal cord by placing transverse barriers that limit toxic solutions to preselected regions only. In all tests, the end point (24 h after the transient application of the experimental insult) is the ability to express locomotor-like rhythmic patterns recorded electrophysiologically from lumbar ventral roots and to correlate this function with cell survival, cell type identification, and demonstration of pathological processes responsible for cell loss. This approach can be useful to investigate the basic mechanisms of action of drugs designed to exert early neuroprotection and the time course of effectiveness against distinct cell types.