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Neuroma-In-Continuity Model in Mice - A Pilot Study
Daniel Umansky, MD, Kathleen Hagen, BSc, Tak Ho Chu, PhD, Shalina S. Ousman, PhD and Rajiv Midha, MD, MSc, University of Calgary, Calgary, AB, Canada

Title: Neuroma-In-Continuity Model in Mice - A Pilot Study

 

Introduction: Creating the optimal neuroma-in-continuity (NIC) model has been a long sought-after goal in experimental peripheral nerve surgery research. Our group has previously created a verified traumatic NIC model in rats. We present our current work of NIC in a mouse model to facilitate future drug targeted therapies to the regenerating nerve. 

 

Materials & Methods: Unilateral sciatic nerves of nineteen C57BL/6 (N=8) and 129S6/SvEvTac (N=11) adult mice were surgically exposed and underwent a uniformly combined crush and stretch injury using a custom designed spacer. Injury specifications were done in preliminary work to achieve a Sunderland grade 4 injury and then replicated for consistency. Nerves were harvested at 6 days (+/- 1 day post-injury; N=14) for histological serial longitudinal evaluation of microarchitecture and compared to acutely (0 days post-injury; N=5) injured nerves and uninjured contralateral nerves. 

 

Results: At one week following injury, histological studies confirmed both a grade 3 axonotmetic injury with endoneurium disruption but fascicular sparing and a grade 4 axonotmetic injury with a severe NIC while the epineurium remained intact (Fig.1). Ongoing work is evaluating the electrophysiological and behavioural consequences in a cohort of serially assessed mice receiving NIC versus simple crush injuries.   

 

Conclusion: This is the first report of a reproducible crush-stretch injury in a mouse model. Graded controlled injury is achievable through different biomechanical applied forces. Ongoing work encompassing behavioral and functional studies of a larger group of animals will be available for presentation at the conference. 

 

Fig.1

Fig1. Longitudinal immunohistochemistry sciatic nerve stretch-crush injury at day 6 neuroma-in-continuity (NIC)

Top panel single nerve following stretch-crush injury. Left to right: proximal (Prox), injury site (NIC) and distal site (Dist). Lower panel proximal and NIC site of stretch-crushed nerve. Lower right is control- crush only injury site.  

Markers key-code: Red- Neurofilament, Green- Glut1 to demonstrate perineurium and its disruption in NIC, Blue- DAPI


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