Taking the Next Step: a Neural Coaptation Orthotopic Hind Limb Transplant Model to Maximize Functional Recovery in Rat

Feibo Zheng; Andy Tully; Kyle M Koss; Xiaomin Zhang; Longhui Qiu; Jiao-Jing Wang; Bilal A Naved; David  Z Ivancic; James M Mathew; Jason  A Wertheim; Zheng  Jenny Zhang

doi:10.3791/60777

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Method Article

Taking the Next Step: a Neural Coaptation Orthotopic Hind Limb Transplant Model to Maximize Functional Recovery in Rat

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DOI:

10.3791/60777

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August 30th, 2020

Feibo Zheng¹^,³ , Andy Tully¹^,² , Kyle M Koss¹ , Xiaomin Zhang¹ , Longhui Qiu¹ , Jiao-Jing Wang¹ , Bilal A Naved¹^,⁴ , David Z Ivancic¹ , James M Mathew¹ , Jason A Wertheim¹ , Zheng Jenny Zhang¹

¹Comprehensive Transplant Center and Department of Surgery, Feinberg School of Medicine, Northwestern University, ²Department of Surgery, University of Illinois at Chicago, ³Department of Surgery, Tianjin Occupational Diseases Precaution and Therapeutic Hospital, ⁴Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University

Summary

This protocol presents a robust, reproducible model of vascularized composite allotransplant (VCA) geared toward simultaneous study of immunology and functional recovery. The time invested in meticulous technique in a right mid-thigh hind limb orthotopic transplant with hand sewn vascular anastomoses and neural coaptation yields the ability to study functional recovery.

Abstract

Limb transplant in particular and vascularized composite allotransplant (VCA) in general have wide therapeutic promise that have been stymied by current limitations in immunosuppression and functional neuromotor recovery. Many animal models have been developed for studying unique features of VCA, but here we present a robust reproducible model of orthotopic hind limb transplant in rats designed to simultaneously investigate both aspects of current VCA limitation: immunosuppression strategies and functional neuromotor recovery. At the core of the model rests a commitment to meticulous, time-tested microsurgical techniques such as hand sewn vascular anastomoses and hand sewn neural coaptation of the femoral nerve and the sciatic nerve. This approach yields durable limb reconstructions that allow for longer lived animals capable of rehabilitation, resumption of daily activities, and functional testing. With short-term treatment of conventional immunosuppressive agents, allotransplanted animals survived up to 70 days post-transplant, and isotransplanted animals provide long lived controls beyond 200 days post-operatively. Evidence of neurologic functional recovery is present by 30 days post operatively. This model not only provides a useful platform for interrogating immunological questions unique to VCA and nerve regeneration, but also allows for in vivo testing of new therapeutic strategies specifically tailored for VCA.

Introduction

Limb transplant under the broader category of vascularized-composite allotransplant (VCA) or composite tissue allotransplant (CTA) has yet to fulfill its therapeutic promise. Since the first successful human hand transplants in Lyon, France and Louisville, Kentucky in 1998 and 1999, over 100 upper extremity transplants have been performed worldwide in carefully selected patients¹. Wider applicability has been stymied by substantial immunosuppression and limited functional neuromotor recovery. Current immunosuppression strategies result in 85% incidence of acute rejection in the face of 77% incidence of opportunistic infection^2....