Effect of TGF-b1&2 antibodies on neural scarring after repair

Objective: Neutralising antibodies to TGF- b1 & TGF- b2 have been shown to significantly reduce scarring when applied to a skin wound in rats. We have investigated the effect of applying these agents to a peripheral nerve at the time of repair, as scar formation can impede recovery. Methods: The left sciatic nerve was exposed under general anaesthesia (Fentanyl/Fluanisone 0.8ml/kg & Midazolam 4mg/kg, i.p. Janissen/Roche) in 18 adult Sprague-Dawley rats. In 12 animals the nerve was sectioned and immediately re-approximated using 4 epineurial sutures, and in 6 of these neutralising antibodies to TGF-b1 & TGF-b2 (100µg of each in 100µl PBS, R & D systems) were injected into and around the proximal and distal nerve stumps. The 6 other animals acted as controls. After 7 weeks the nerves were harvested and a 4mm segment across the repair site (or an equivalent site in controls) was fixed in paraformaldehyde and prepared for light microscopy. Longitudinal 14µm cryostat sections were stained for collagen using picrosirius red, and the extent of staining quantified using image analysis. Results: In controls, the mean percentage area of staining (PAS) for collagen within the nerve (excluding the epineurium) was 1.94%. After repair the PAS had significantly increased to 5.76% (p<0.005, Student’s t-test). However, after repair with the administration of antibodies, the PAS was not significantly different from controls (3.60%, p>0.05). Conclusions: We conclude that administration of neutralising antibodies to TGF- b1 & TGF-2 b reduces scar formation after peripheral nerve repair. Supported by the Wellcome Trust.