Conservative Safety Assessment of a Nitinol Microhook Coaptation Device on Intact Nerve

INTRODUCTION/AIMS: Nerve Tape is a novel nerve coaptation device that eliminates the technical challenges of microsuturing. The device incorporates tissue-engaging Nitinol microhooks within a flexible backing of decellularized porcine small intestine submucosa (SIS). Preclinical nerve injury models have demonstrated device safety and effective promotion of regeneration and recovery. Here, we further assess the impact of the device's components on nerve tissue and function, using a highly conservative model in which the device is applied to intact nerves.

METHODS: Nerve Tape, sutures, or SIS were applied to rabbit tibial nerves in a manner simulating transection repairs but leaving the nerves intact. After three months, "repaired" nerves and target gastrocnemius muscles along with contralateral control nerves and muscles were evaluated for perineural scarring, inflammation, and function utilizing gross inspection, morphology measurements, electrophysiology, and histology.

RESULTS: Analysis of endpoint data, including muscle mass/girth, nerve compound action potential (NCAP) amplitude, conduction velocity, axon counts, and g-ratio revealed no significant differences between experimental or control groups (distal axon count/g-ratio: Nerve Tape 6546 ± 2300, 0.647 ± 0.04; Suture 7979 ± 666, 0.664 ± 0.033; SIS 7537 ± 2117, 0.689 ± 0.02; control 6158 ± 1958, 0.631 ± 0.02). Gross adhesion thickness at the treatment site was higher in the Suture group versus the Nerve Tape group. Granulomas and neovascularization were most pronounced in the Suture group. Macrophage/lymphocyte/plasma cell presence was associated with SIS material. No additional tissue response was observed in response to Nitinol components.

DISCUSSION: Nerve Tape's SIS and Nitinol microhook design maintained the health of an intact nerve with sequelae comparable to sutures or SIS without microhooks.