Comparison of Potential Nerve Scar Agents in the Rat Model

Abstract

Abstract Background An animal nerve scar model that can be used to identify potential therapies in the treatment of nerve scarring in patients has yet to be defined. The purpose of this study was to create an inexpensive, reproducible, and reliable nerve scar model in the rat. Methods Thirty rats underwent left tibial nerve transection and repair and were divided into three groups: 10 controls with transection and repair alone, 10 receiving topical application of talc powder onto the repair, and 10 receiving topical application of tetracycline onto the repair. Outcome measures included weekly extensor postural thrust (EPT) testing for 12 weeks, endpoint gastrocnemius weight ratios (left vs right), and histological analysis. Results The tetracycline group showed a significant difference in EPT testing at week 6 postoperatively (p = 0.007) and had the lowest average EPT value at each time point over 12 weeks. Each group displayed a plateau in recovery, with the control and talc groups reaching plateau 1 week earlier (week 6) than the tetracycline group (week 7). At 12 weeks postoperatively, there was no significant difference in EPT testing (p = 0.301) or gastrocnemius weight ratios (p = 0.802). Histological analysis showed substantial nerve regeneration in the control group, an inflammatory response in the epineurium of the talc and tetracycline groups, but no migration of inflammation or interference of nerve regeneration in the endoneurial compartment. Conclusion These agents, and more importantly, this animal model are inadequate for developing a nerve scar. Identifying a better animal with more connective tissue should be further explored.

Keywords

• nerve
• rat model
• scar