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Nogo receptor deletion and multimodal exercise improve distinct aspects of recovery in cervical spinal cord injury.

ABSTRACT: We tested the ability of two plasticity-promoting approaches to enhance recovery in a mouse model of incomplete spinal cord injury (SCI). Genetically, we reduced myelin-mediated inhibition of neural plasticity through Nogo66-receptor (NgR) gene deletion. Behaviorally, we utilized a novel multimodal exercise training paradigm. Adult mice of wild-type or NgR-null genotype were subjected to partial lateral hemisection (LHx) at C3-C4 with the intent of producing anatomically and functionally mild deficits. Exercise training or control treatment proceeded for 14 weeks. Behavioral outcomes were assessed prior to tract tracing and histological analysis. Genotype and training exerted differing effects on performance; training improved performance on a test related to the training regimen (task-specific benefit), whereas genotype also improved performance on more generalized behaviors (task-non-specific benefit). There were no significant histological differences across genotype or training assignment with regard to lesion size or axonal tract staining. Thus either NgR gene deletion or exercise training benefits mice with mild cervical spinal injury. In this lesion model, the effects of NgR deletion and training were not synergistic for the tasks assessed. Further work is required to optimize the interaction between pharmacological and physical interventions for SCI.

SUBMITTER: Harel NY

PROVIDER: S-EPMC2978056 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Nogo receptor deletion and multimodal exercise improve distinct aspects of recovery in cervical spinal cord injury.

Harel Noam Y NY Song Kang-Ho KH Tang Xin X Strittmatter Stephen M SM

Journal of neurotrauma 20101101 11

We tested the ability of two plasticity-promoting approaches to enhance recovery in a mouse model of incomplete spinal cord injury (SCI). Genetically, we reduced myelin-mediated inhibition of neural plasticity through Nogo66-receptor (NgR) gene deletion. Behaviorally, we utilized a novel multimodal exercise training paradigm. Adult mice of wild-type or NgR-null genotype were subjected to partial lateral hemisection (LHx) at C3-C4 with the intent of producing anatomically and functionally mild de ...[more]

PMID: 20809785

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Project description:After CNS trauma such as spinal cord injury, the ability of surviving neural elements to sprout axons, reorganize neural networks and support recovery of function is severely restricted, contributing to chronic neurological deficits. Among limitations on neural recovery are myelin-associated inhibitors functioning as ligands for neuronal Nogo receptor 1 (NgR1). A soluble decoy (NgR1-Fc, AXER-204) blocks these ligands and provides a means to promote recovery of function in multiple preclinical rodent models of spinal cord injury. However, the safety and efficacy of this reagent in non-human primate spinal cord injury and its toxicological profile have not been described. Here, we provide evidence that chronic intrathecal and intravenous administration of NgR1-Fc to cynomolgus monkey and to rat are without evident toxicity at doses of 20 mg and greater every other day (≥2.0 mg/kg/day), and far greater than the projected human dose. Adult female African green monkeys underwent right C5/6 lateral hemisection with evidence of persistent disuse of the right forelimb during feeding and right hindlimb during locomotion. At 1 month post-injury, the animals were randomized to treatment with vehicle (n = 6) or 0.10-0.17 mg/kg/day of NgR1-Fc (n = 8) delivered via intrathecal lumbar catheter and osmotic minipump for 4 months. One animal was removed from the study because of surgical complications of the catheter, but no treatment-related adverse events were noted in either group. Animal behaviour was evaluated at 6-7 months post-injury, i.e. 1-2 months after treatment cessation. The use of the impaired forelimb during spontaneous feeding and the impaired hindlimb during locomotion were both significantly greater in the treatment group. Tissue collected at 7-12 months post-injury showed no significant differences in lesion size, fibrotic scar, gliosis or neuroinflammation between groups. Serotoninergic raphespinal fibres below the lesion showed no deficit, with equal density on the lesioned and intact side below the level of the injury in both groups. Corticospinal axons traced from biotin-dextran-amine injections in the left motor cortex were equally labelled across groups and reduced caudal to the injury. The NgR1-Fc group tissue exhibited a significant 2-3-fold increased corticospinal axon density in the cervical cord below the level of the injury relative to the vehicle group. The data show that NgR1-Fc does not have preclinical toxicological issues in healthy animals or safety concerns in spinal cord injury animals. Thus, it presents as a potential therapeutic for spinal cord injury with evidence for behavioural improvement and growth of injured pathways in non-human primate spinal cord injury.

Project description:BACKGROUND AND PURPOSE:Spared fibers after spinal cord injury (SCI) tend to consist predominantly of subcortical circuits that are not under volitional (cortical) control. We aim to improve function after SCI by using targeted physical exercises designed to simultaneously stimulate cortical and spared subcortical neural circuits. METHODS:Participants with chronic motor-incomplete SCI enrolled in a single-center, prospective interventional crossover study. Participants underwent 48 sessions each of weight-supported robotic-assisted treadmill training and a novel combination of balance and fine hand exercises, in randomized order, with a 6-week washout period. Change post-intervention was measured for lower extremity motor score, soleus H-reflex facilitation; seated balance function; ambulation; spasticity; and pain. RESULTS:Only 9 of 21 enrolled participants completed both interventions. Thirteen participants completed at least one intervention. Although there were no statistically significant differences, multimodal training tended to increase short-interval H-reflex facilitation, whereas treadmill training tended to improve dynamic seated balance. DISCUSSION:The low number of participants who completed both phases of the crossover intervention limited the power of this study to detect significant effects. Other potential explanations for the lack of significant differences with multimodal training could include insufficient engagement of lower extremity motor cortex using skilled upper extremity exercises; and lack of skill transfer from upright postural stability during multimodal training to seated dynamic balance during testing. To our knowledge, this is the first published study to report seated posturography outcomes after rehabilitation interventions in individuals with SCI. CONCLUSION:In participants with chronic incomplete SCI, a novel mix of multimodal exercises incorporating balance exercises with skilled upper extremity exercises showed no benefit compared to an active control program of body weight-supported treadmill training. To improve participant retention in long-term rehabilitation studies, subsequent trials would benefit from a parallel group rather than crossover study design.

Dataset Information

Nogo receptor deletion and multimodal exercise improve distinct aspects of recovery in cervical spinal cord injury.

Publications

Nogo receptor deletion and multimodal exercise improve distinct aspects of recovery in cervical spinal cord injury.

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