Stimulation and repair of peripheral nerves using a bioadhesive graft-antenna (Conference Presentation)

Peripheral nerve injuries are difficult to treat because axon regeneration is limited and functional recovery is often unsatisfactory in patients. Brief electrical stimulation of injured nerves is emerging as a new promising therapy that can relieve pain or induce better axon regeneration and functional recovery than untreated nerves. In this study, we report an innovative wireless and biocompatible stimulator that is also a scaffold for injured nerves when an autograft is applied to bridge a gap in rat sciatic nerves. We have named this device “graft-antenna” to highlight the double functionality of the implant. The scaffold is made of chitosan and incorporates a gold loop antenna (diameter ~1.3 mm, thickness ~70 nm) powered wirelessly by a transcranial magnetic stimulator (TMS). The device is bonded to tissue non-invasively and without sutures, exploiting the photo-adhesion properties of the chitosan scaffold. The stimulator did not migrate after implantation on healthy sciatic nerves in rats and was able to trigger a steady compound muscle action potential for 12 weeks (CMAP ~1.3 mV). No CMAP was elicited by the TMS when the wireless stimulator was not implanted on nerves. Axon regeneration was facilitated in sciatic nerves that were grafted with the graft-antenna and stimulated for 1 hour, once a week (magnetic field magnitude~0.72 T, pulse duration ~350 μs, repetition rate=1 pulse/sec). Eight weeks post-operatively, myelinated axon count, CMAP and nerve conduction velocity were statistically higher in the graft-antenna group (n=5) than in nerves grafted with the chitosan scaffold without antenna.