Neuroprosthetic technologies to augment the impact of neurorehabilitation after spinal cord injury.

Spinal cord injury leads to a range of disabilities, including limitations in locomotor activity, that seriously diminish the patients' autonomy and quality of life. Electrochemical neuromodulation therapies, robot-assisted rehabilitation and willpower-based training paradigms restored supraspinal control of locomotion in rodent models of severe spinal cord injury. This treatment promoted extensive and ubiquitous remodeling of spared circuits and residual neural pathways. In four chronic paraplegic individuals, electrical neuromodulation of the spinal cord resulted in the immediate recovery of voluntary leg movements, suggesting that the therapeutic concepts developed in rodent models may also apply to humans. Here, we briefly review previous work, summarize current developments, and highlight impediments to translate these interventions into medical practice to improve functional recovery of spinal-cord-injured individuals.

Multisystem neuroprosthetic training improves bladder function after severe spinal cord injury.

UNLABELLED: Severe spinal cord injury leads to neurogenic bladder dysfunction. We recently developed a multisystem neuroprosthetic training program that promotes plastic changes capable of restoring refined locomotion in rats with severe spinal cord injury. We investigated whether multisystem neuroprosthetic training would influence the development of posttraumatic bladder dysfunction. MATERIALS AND METHODS: Eight and 4 adult rats were randomly assigned to a spinal cord injury and an intact control group, respectively. Spinal cord injury consisted of 2 opposite lateral hemisections (T7 and T11), thus, interrupting all direct supraspinal input. After spinal cord injury 4 rats were subjected to a multisystem neuroprosthetic training program and 4 were not trained. At 8 weeks we performed urodynamics and evaluated kidney function using creatinine and cystatin C. Bladder investigation included morphological, histological and immunohistochemical evaluations. RESULTS: Bladder capacity increased threefold in trained and sevenfold in nontrained rats compared to intact rats. During filling we found a mean ± SEM of 2.7 ± 1.1 vs 12.6 ± 5.2 nonvoiding contractions in trained vs nontrained rats. Bladder morphology was similar in trained and intact rats. Nontrained rats showed detrusor hypertrophy, characterized by increased detrusor thickness and a decreased connective tissue-to-smooth muscle ratio. As labeled with protein gene product 9.5, general nerve density was significantly increased in trained and significantly decreased in nontrained rats. The relative proportion of neurofilament 200 positive afferent nerves was significantly lower in trained than in intact and nontrained rats. Neuropeptide Y positive fibers showed significantly lower density in nontrained rats. CONCLUSIONS: Multisystem neuroprosthetic training effectively counteracts the formation of neurogenic bladder dysfunction after severe spinal cord injury and might contribute to preserving bladder function and preventing long-term complications in patients with severe spinal cord injury.

Combinatory electrical and pharmacological neuroprosthetic interfaces to regain motor function after spinal cord injury.

Severe lesions of the rodent or human spinal cord lead to permanent paralysis of the legs. Here, we review novel evidences suggesting that interventions combining pharmacological and electrical stimulations of the spinal cord have a high potential to promote the recovery of locomotion following severe spinal cord injuries in humans. These strategies are based on the existence of webs of circuits and receptors embedded in the spinal motor infrastructure that each modulate specific aspects of locomotor movements. We show that chemical or electrical stimulations can engage specific elements of this spinal machinery, thus resulting in distinct patterns of locomotion in paralyzed spinal rats. In turn, simultaneous chemical stimulations of neural receptors and/or electrical stimulations of multiple spinal segments can synergistically facilitate locomotor movements. These preliminary results provide a strong rationale for the development of neuroprosthetic chemotrode and electrode arrays that would enable a detailed and distributed access to the different elements of the spinal motor infrastructure. Such novel biomedical technologies may offer unparalleled potential to induce multiple and flexible locomotor states in paralyzed subjects.