Tiam Mana Saffari

214 CHAPTER 10 MATERIALS AND METHODS Animal experiments were approved by the Mayo Clinic Institutional Animal Care and Use Committee (IACUC A3348-18). Experimental design Twenty-five male Lewis rats, weighing between 250-300 grams (Envigo, USA), were randomly divided into five groups to reconstruct unilateral sciatic nerve gaps, depicted in Table 1. In group I, a unilateral 10-mm sciatic nerve gap was repaired with an ipsilateral reversed autologous graft to create a mismatch in the alignment of nerve fibers (gold standard). For group II-V, decellularized allograft nerves were used to reconstruct the nerve gap. In group II, a 10-mm allograft was used to reconstruct the nerve gap. In group III-V, these nerve allografts were placed in a vascularized bed using a pedicled superficial inferior epigastric artery fascia (SIEF) flap to provide surgical angiogenesis 6 . Prior to surgery of group IV and V, allografts were dynamically seeded with undifferentiated MSCs and MSCs differentiated into Schwann cell-like cells, respectively, combining stem cells and surgical angiogenesis. After survival of two weeks, Microfil® was injected to preserve vasculature and microcomputed tomography (micro CT) analysis of blood vessel morphology and distribution was performed 12 . Results were compared to non-operated sciatic nerve (control) samples (N=10). Table 1. Experimental design. dMSC: differentiated mesenchymal stem cells, SIEF: superficial inferior epigastric artery fascial (SIEF) flap, uMSC: undifferentiated mesenchymal stem cells. Groups Description Survival time 2 weeks (N) Outcome measurements I Autograft Autograft 5 Micro computed analysis • Vascular volume • Volume of vessels (mm 3 ) • Percentage of vessels (%) II Allograft Decellularized allograft 5 III SIEF Decellularized allograft + SIEF flap 5 IV uMSCs + SIEF Decellularized allograft + undifferentiated MSCs + SIEF flap 5 V dMSCs + SIEF Decellularized allograft + differentiated MSCs + SIEF flap 5