189 Novel Wireless Battery-Free Fully Passive Flexible Brain/Spine Implant for Improved Recovery of Function Through Epidural Stimulation

Abstract

INTRODUCTION: Acquired motor impairment from diseases such as stroke, trauma, epilepsy, and cancer remains an important cause of disability. Current treatments provide insufficient brain/spine recovery, with most patients failing to recover adequate motor function with rehabilitation alone. Brain stimulation can lead to enhanced synaptic density and synaptic response after long-term stimulation and enhanced motor function recovery. However, non-invasive options remain inadequate and invasive approaches are associated with unacceptable risks. METHODS: A flexible and transparent silicone elastomer substrate was used through microfabrication processes, with an external antenna near the implant to control the stimulation. In vitro validation was accomplished by wireless stimulation of human-induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs). In vivo validation was performed by motor cortex stimulation on an anesthetized rat. The corresponding hindlimb motion was captured by video. To separate implant-evoked movement from spontaneous movement, we compared the peak hindlimb velocity during 0.5 sec post-stimulation periods vs. the 0.5 sec pre-stimulation periods, across a continuous series of N = 43 stimulation pulses. RESULTS: Cultured hiPSC-CMs cells demonstrated well-controlled beating behavior under 0.5, 1, and 2Hz wireless stimulation. Statistical analysis further confirmed the change in beating rate corresponded with stimulation frequency (p < 0.001). The recorded hindlimb movement under wireless motor cortex stimulation demonstrated synchronization with the delivered voltage pulse trains. Average peak hindlimb velocity during pre-stimulation periods was 0.8 ± 0.4 mm/sec (± S.D.); during post-stimulation periods, 47 ± 13 mm/sec. A two-sample t-test confirmed the applied wireless power directly evoked movement, (p < 0.001). CONCLUSIONS: We have developed a wireless, battery-less implant with demonstrated efficacy in vitro and in vivo. Efforts at long-term safety evaluation are ongoing in a smaller and larger animal model as a bridge to phase 0/1 clinical trials.