Methods: Regeneration of the sciatic nerve was assessed in C57-black-6 mice. Under general anaesthesia (Fentanyl/Fluanisone 0.8ml/kg [Janssen] & Midazolam 4mg/kg [Roche], i.p.) the nerve was sectioned and repaired using 4 epineurial sutures. In two groups (8 animals/group) TGFβ-3 (50ng or 500ng in 100µl of saline carrier) was injected into and around the proximal and distal nerve stumps. A third group had 100µl of phosphate buffered saline injected alone, and comparisons were also made with a sham-operated control group. After 6 weeks the extent of regeneration was assessed electrophysiologically by determining the ratio of the compound action potential (CAP) modulus evoked by electrical stimulation of the nerve 2mm distal or proximal to the repair site. The percentage area of collagen staining (PAS) at the repair site was analysed using picrosirius red and image analysis.
Results: The median PAS for collagen in the saline group was 5.35%, which was not significantly different from either TGFβ-3 group (50ng: median 5.83%, 500ng: 6.12%, p>0.05 Kruskal-Wallis test). All three injury groups had a significantly higher PAS than the sham-operated controls (1.7%, p<0.05). The median CAP ratio in the saline group was 0.34, which was not significantly different from either TGFβ-3 group (50ng: median 0.49, 500ng: 0.45, p>0.05). All three injury groups had a significantly smaller CAP ratio than the sham-operated controls (0.92, p<0.05).
Conclusion: Our method and dosage for administration of TGFβ-3 did not reduce intraneural scarring or enhance regeneration of sectioned axons in the mouse sciatic nerve.
Supported by the Wellcome Trust (074500).