A novel nerve transection and repair method in mice: histomorphometric analysis of nerves, blood vessels, and muscles with functional recovery.

Peripheral nerve transection is associated with permanent functional deficit even after advanced microsurgical repair. While it is difficult to investigate the reasons of poor functional outcomes of microsurgical repairs in humans, we developed a novel pre-clinical nerve transection method that allows reliable evaluation of nerve regeneration, neural angiogenesis, muscle atrophy, and functional recovery. Adult male C57BL/6 mice were randomly assigned to four different types of sciatic nerve transection: Simple Transection (ST), Simple Transection & Glue (TG), Stepwise Transection and Sutures (SU), and Stepwise Transection and Glue (STG). Mice were followed for 28 days for sciatic function index (SFI), and sciatic nerves and hind limb muscles were harvested for histomorphological and cellular analyses. Immunohistochemistry revealed more directional nerve fiber growth in SU and STG groups compared with ST and TG groups. Compared to ST and TG groups, optimal neural vessel density and branching index in SU and STG groups were associated with significantly decreased muscle atrophy, increased myofiber diameter, and improved SFI. In conclusion, our novel STG method represents an easily reproducible and reliable model with close resemblance to the pathophysiological characteristics of SU model, and this can be easily reproduced by any lab.