Combinational Spinal GAD65 Gene Delivery and Systemic GABA-Mimetic Treatment for Modulation of Spasticity

receptor agonist), while effective in modulating spasticity is associated with major side effects such as general sedation and progressive tolerance development. The goal of the present study was to assess if a combined therapy composed of spinal segment-specific upregulation of GAD65 (glutamate decarboxylase) gene once combined with systemic treatment with tiagabine (GABA uptake inhibitor) will lead to an antispasticity effect and whether such an effect will only be present in GAD65 gene over-expressing spinal segments.Adult Sprague-Dawley (SD) rats were exposed to transient spinal ischemia (10 min) to induce muscle spasticity. Animals then received lumbar injection of HIV1-CMV-GAD65 lentivirus (LVs) targeting ventral α-motoneuronal pools. At 2–3 weeks after lentivirus delivery animals were treated systemically with tiagabine (4, 10, 20 or 40 mg/kg or vehicle) and the degree of spasticity response measured. In a separate experiment the expression of GAD65 gene after spinal parenchymal delivery of GAD65-lentivirus in naive minipigs was studied. Spastic SD rats receiving spinal injections of the GAD65 gene and treated with systemic tiagabine showed potent and tiagabine-dose-dependent alleviation of spasticity. Neither treatment alone (i.e., GAD65-LVs injection only or tiagabine treatment only) had any significant antispasticity effect nor had any detectable side effect. Measured antispasticity effect correlated with increase in spinal parenchymal GABA synthesis and was restricted to spinal segments overexpressing GAD65 gene.These data show that treatment with orally bioavailable GABA-mimetic drugs if combined with spinal-segment-specific GAD65 gene overexpression can represent a novel and highly effective anti-spasticity treatment which is associated with minimal side effects and is restricted to GAD65-gene over-expressing spinal segments

Thoracic 9 Spinal Transection-Induced Model of Muscle Spasticity in the Rat: A Systematic Electrophysiological and Histopathological Characterization.

The development of spinal hyper-reflexia as part of the spasticity syndrome represents one of the major complications associated with chronic spinal traumatic injury (SCI). The primary mechanism leading to progressive appearance of muscle spasticity is multimodal and may include loss of descending inhibitory tone, alteration of segmental interneuron-mediated inhibition and/or increased reflex activity to sensory input. Here, we characterized a chronic thoracic (Th 9) complete transection model of muscle spasticity in Sprague-Dawley (SD) rats. Isoflurane-anesthetized rats received a Th9 laminectomy and the spinal cord was transected using a scalpel blade. After the transection the presence of muscle spasticity quantified as stretch and cutaneous hyper-reflexia was identified and quantified as time-dependent changes in: i) ankle-rotation-evoked peripheral muscle resistance (PMR) and corresponding electromyography (EMG) activity, ii) Hoffmann reflex, and iii) EMG responses in gastrocnemius muscle after paw tactile stimulation for up to 8 months after injury. To validate the clinical relevance of this model, the treatment potency after systemic treatment with the clinically established anti-spastic agents baclofen (GABAB receptor agonist), tizanidine (α2-adrenergic agonist) and NGX424 (AMPA receptor antagonist) was also tested. During the first 3 months post spinal transection, a progressive increase in ankle rotation-evoked muscle resistance, Hoffmann reflex amplitude and increased EMG responses to peripherally applied tactile stimuli were consistently measured. These changes, indicative of the spasticity syndrome, then remained relatively stable for up to 8 months post injury. Systemic treatment with baclofen, tizanidine and NGX424 led to a significant but transient suppression of spinal hyper-reflexia. These data demonstrate that a chronic Th9 spinal transection model in adult SD rat represents a reliable experimental platform to be used in studying the pathophysiology of chronic spinal injury-induced spasticity. In addition a consistent anti-spastic effect measured after treatment with clinically effective anti-spastic agents indicate that this model can effectively be used in screening new anti-spasticity compounds or procedures aimed at modulating chronic spinal trauma-associated muscle spasticity

Amelioration of motor/sensory dysfunction and spasticity in a rat model of acute lumbar spinal cord injury by human neural stem cell transplantation

INTRODUCTION: Intraspinal grafting of human neural stem cells represents a promising approach to promote recovery of function after spinal trauma. Such a treatment may serve to: I) provide trophic support to improve survival of host neurons; II) improve the structural integrity of the spinal parenchyma by reducing syringomyelia and scarring in trauma-injured regions; and III) provide neuronal populations to potentially form relays with host axons, segmental interneurons, and/or α-motoneurons. Here we characterized the effect of intraspinal grafting of clinical grade human fetal spinal cord-derived neural stem cells (HSSC) on the recovery of neurological function in a rat model of acute lumbar (L3) compression injury. METHODS: Three-month-old female Sprague–Dawley rats received L3 spinal compression injury. Three days post-injury, animals were randomized and received intraspinal injections of either HSSC, media-only, or no injections. All animals were immunosuppressed with tacrolimus, mycophenolate mofetil, and methylprednisolone acetate from the day of cell grafting and survived for eight weeks. Motor and sensory dysfunction were periodically assessed using open field locomotion scoring, thermal/tactile pain/escape thresholds and myogenic motor evoked potentials. The presence of spasticity was measured by gastrocnemius muscle resistance and electromyography response during computer-controlled ankle rotation. At the end-point, gait (CatWalk), ladder climbing, and single frame analyses were also assessed. Syrinx size, spinal cord dimensions, and extent of scarring were measured by magnetic resonance imaging. Differentiation and integration of grafted cells in the host tissue were validated with immunofluorescence staining using human-specific antibodies. RESULTS: Intraspinal grafting of HSSC led to a progressive and significant improvement in lower extremity paw placement, amelioration of spasticity, and normalization in thermal and tactile pain/escape thresholds at eight weeks post-grafting. No significant differences were detected in other CatWalk parameters, motor evoked potentials, open field locomotor (Basso, Beattie, and Bresnahan locomotion score (BBB)) score or ladder climbing test. Magnetic resonance imaging volume reconstruction and immunofluorescence analysis of grafted cell survival showed near complete injury-cavity-filling by grafted cells and development of putative GABA-ergic synapses between grafted and host neurons. CONCLUSIONS: Peri-acute intraspinal grafting of HSSC can represent an effective therapy which ameliorates motor and sensory deficits after traumatic spinal cord injury