Hyaluronic acid through a new injectable nerve guide delivery system enhances peripheral nerve regeneration in the rat.

The use of non-neural conduits to bridge gaps in peripheral nerves has been noted in the literature for many years. A logical extension of this concept is the introduction of neurotrophic or growth promoting factors into the lumen. We present here an injectable nerve guide that allows percutaneous access to the microenvironment of the regenerating peripheral nerve within the guide's lumen. Hyaluronic acid, a compound associated with decreased scarring and improved fibrin matrix formation, is added sequentially to the regenerating peripheral rat sciatic nerve via this injectable nerve guide. Assessment of nerve regeneration and reinnervation shows better conduction velocity, higher axon counts, and a trend toward earlier myelination with hyaluronic acid compared with saline. This work not only implies hyaluronic acid's role as an agent that aids nerve growth but also describes a new tool that allows percutaneous access to the milieu of a regenerating nerve.