Effects of chondroitin sulfate supplements on regeneration of bridged sciatic nerves

Abstract

We reported increases in soluble chondroitin sulfate (CS)-containing forms in the crushed sciatic nerves of adult guinea pigs. This suggests that CS plays a role in post-traumatic tissue remodelling and axonal regrowth of the crushed nerve. To test this, defined amounts of CS from whale cartilage, shark cartilage or guinea-pig brain were supplemented to the regenerating environment via a silicone conduit that bridged a critical gap between the two ends of a transected sciatic nerve on one side of the animal. After timed periods of recovery, the animals were assessed for EMG signals at the target gastrocnemius muscle to determine the conduction veolocity across the bridged nerve. Sections of the bridge were also histologically examined for nerve fibres. Initial EMG indication of reconnection with the target was observed when myelinated axons reached 3,000 at the bridge and conduction velocity was about 30% of that in the intact contralateral nerve; this was observed by week 14 for CS-bridged nerves, in contrast to week 9 for PBS-bridged nerves. By week 20, CS-bridged nerves indicated ≥5,000 myelinated axons at the bridge; conduction velocity reached 50% of that in the intact contralateral nerve, similar to that observed in PBS-bridged nerves. The similarity suggests that the injury-induced endogenous CS forms exerted over-riding effects in the bridged nerves. It is unclear how far the endogenous forms differ from the exogenous CS supplements and how the difference affects the regenerative process. Supported by HK Research Grants Council