Functional and morphological repair of rat sciatic nerve with a Hyaff11(,,Y)-based nerve guide

Summary form only given. Biodegradable nerve guides are a good alternative for the use of autologous grafts in peripheral nerve repair. We investigated the use of a Hyaff11-based nerve guide for bridging a 1 cm gap in the rat sciatic nerve. After 7, 15, and 21 weeks, the rats were subjected to walking track analysis and withdrawal reflex tests, and the regenerated nerve tissue with surroundings was explanted and processed. Seven weeks after implantation gait analysis showed functional recovery of the hindleg. Parameters like "walking on plantair side" and "absence of dragging" already scored 100% recovery. Scoring percentage of other parameters such as "alternating steps", "normal swing phase", "hindfeet within body contour" and "fluent walking" increased in the period afterwards. The stimulus strength to evoke a pain withdrawal was 0.42 mA for the regenerated side at week 7, and this values did not decrease until 21 weeks. The control leg needed only a 0.1 mA stimulus to evoke a pain withdrawal at 7, 15, and 21 weeks. At week 7, a thin bundle of nerve tissue was formed. This bundle was however completely surrounded by (collapsed) biomaterial and a chronic foreign body reaction. The diameter of the bundle was increased at week 15 and later, but still a large amount of biomaterial was present. The Hyaff11-based nerve guide restores nerve outgrowth and function but the amount of biomaterial induces a chronic foreign body reaction which hampers the nerve repair process. A more flexible and thinner tube wall might improve the capacity of the nerve guide.