A novel neuroprosthetic interface with the peripheral nervous system using artificially engineered axonal tracts.

OBJECTIVE: We have previously described a technique developed in our laboratory to create transplantable living axon tracts of several centimeters in length. In this paper, we describe how these engineered neural tissue constructs can be used to create a novel neuroelectrical interface with the regenerating peripheral nervous system, to potentially enable afferent and efferent communications with prosthetic devices. METHODS: Using continuous mechanical tension, we have generated axon tracts of up to 10 cm in length, spanning two populations of neurons in vitro. We have now adapted this stretch-growth paradigm to include a mechanically compliant multi-electrode array that is attached to one of the neuron populations. Once the desired axon length has been reached, the neuroelectrode construct is completely embedded in a supportive hydrogel matrix and affixed to the transected sciatic nerve. RESULTS: Building upon our previous work with peripheral nerve repair, we have designed our neural interface to ensure transplant stability and firm attachment to the electrode array substrate. DISCUSSION: Our preliminary findings indicate that the interface not only maintains its orientation, but also is conducive to host nerve ingrowth. Our ongoing analysis seeks to characterize transplanted neuronal survival, synaptic integration, and functional connectivity. This research provides an opportunity to evaluate an entirely new approach in restoring motor and sensory functions of patients with peripheral nerve damage.

Neural engineering to produce in vitro nerve constructs and neurointerface.

OBJECTIVE: Recently, our laboratory recapitulated a natural form of axon growth that occurs between late embryogenesis and early adulthood. In this article, we describe how this novel neural engineering approach may be used to produce a nervous tissue interface to integrate disconnected motor and sensory functions for external control. METHODS: For nervous system repair, we recently developed a unique method to engineer nervous tissue constructs in vitro consisting of bundles of axons spanning two populations of neuronal somata. To integrate electronics and nervous tissue to transform electrophysiological signals into electronic signals, we have designed a nervous tissue interface. RESULTS: Our nervous tissue interface consists of stretch-grown nervous tissue with one end interfaced with a multiple electrode array, enabling us to detect and record real-time efferent signals conducted down the nerve and stimulate afferent sensory signaling. CONCLUSION: Our ultimate goal is to develop a neurally controlled prosthesis and a nervous system interface that could be linked to the patient's thoughts, providing two-way signaling for motor control and feedback from multiple external stimuli.