Vascularized Brachial Plexus Allotransplantation – An Experimental Study in Brown Norway and Lewis Rats

Background Brachial plexus injuries are devastating. Current reconstructive treatments achieve limited partial functionality. Vascularized brachial plexus allotransplantation could offer the best nerve graft fulfilling the like-with-like principle. In this experimental study, we assessed the feasibility of rat brachial plexus allotransplantation and analyzed its functional outcomes. Methods A free vascularized brachial plexus with a chimeric compound skin paddle flap based on the subclavian vessels was transplanted from a Brown Norway rat to a Lewis rat. This study has 2 parts. Protocol I aimed to develop the vascularized brachial plexus allotransplantation-model (VBP-allo). Four groups are compared: no reconstruction, VBP-allo with and without Cyclosporine-A (CsA) immunosuppression, VBP autotransplantation (VBP-auto). Protocol II compared the recovery of the biceps muscle and forearm flexors when using all 5, 2 (C5+C6) or 1 (isolated C6) spinal nerve as the donor nerves. The assessment was performed on week 16 and included muscle weight, functionality (grooming tests, muscle strength), electrophysiology and histomorphology of the targeted muscles. Results Protocol I showed, the VBP-allo with CsA immunosuppression was electrophysiologically and functionally comparable to VBP-auto and significantly superior to negative controls and absent immunosuppression. In Protocol II, all groups had a comparable functional recovery in the biceps muscle. Only with 5 donor nerves did the forearm show good results compared with only 1 or 2 donor nerves. Conclusions This study demonstrated a useful vascularized complete brachial plexus allotransplantation rodent model with successful forelimb function restoration under immunosuppression. Only the allotransplantation including all 5 roots as donor nerves achieved a forearm recovery. Corresponding Author: David Chwei-Chin Chuang, M.D., Professor, Department of Plastic Surgery, Chang Gung Memorial Hospital, No.5, Fu-Shing St., Taoyuan, Taiwan, Tel.: 886-3-3281200, Ext 3355, Fax: 886-3-3972681, E-mail: dccchuang@gmail.com Authorship Author's specific contributions 1. Participated in research design: David Chwei-Chin Chuang 2. Participated in the writing of the paper: Tommy Nai-Jen Chang, Bassem W Daniel, Kuang-Te Chen, Johhny Chuieng-Yi Lu 3. Participated in the performance of the operation and the sample collection: Tommy Nai-Jen Chang, Kuang-Te Chen, Catherine Hernon 4. Contributed new reagents or analytic tools: Bassem W Daniel, David Chwei-Chin Chuang 5. Participated in data analysis: Tommy Nai-Jen Chang, Catherine Hernon, Mark Shafarenko, Yen-Lin Huang Disclosure The authors hereby declare that they have no conflict of interest in any products used/tested in this study and have nothing to declare. Financial Disclosure: This study was supported by a grant from the Ministry of Science and Technology Taiwan (NSC94-2314-B-182A-176) and the Chang Gung Memorial Hospital, Linkou, Taiwan (CMRPG3A0441-3). None of the authors have a financial interest in any of the products, devices, or drugs mentioned in this article. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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