Cavernous nerve reconstruction with a biodegradable conduit graft and collagen sponge in the rat

Purpose: We investigated the efficacy of a biodegradable conduit graft for axonal regeneration of the injured cavernous nerve in a rat model. Materials and Methods: Bilateral cavernous nerves were resected in 8-week-old Sprague-Dawley rats. We interposed a nerve gap with a 4 mm poly L-lactic acid and E-caprolactone copolymer conduit. The 56 rats were divided into 4 groups, namely group 1-biodegradable conduit alone, group 2-biodegradable conduit plus collagen sponge, group 3-sham operation as a positive control and group 4-unconnected conduit as a negative control. Results: Immunohistochemical study revealed that neuronal nitric oxide synthase positive nerve fibers significantly increased in all rats in the conduit graft groups at 3 months. In a retrograde tracing study with FluoroGold (Fluorochrome, Englewood, Colorado) at 3 months the conduit plus collagen group showed a significant increase in FluoroGold positive cells in major pelvic ganglia. Intracavernous pressure elicited by medial preoptic area stimulation significantly increased in all rats in the conduit graft groups, especially in the conduit plus collagen group. Conclusions: This study suggests that a biodegradable conduit is effective for axonal regeneration of the injured cavernous nerve. Moreover, a conduit with a collagen sponge facilitates axonal sprouting and re-projection to its target organ, and ensures functional recovery.