Tiam Mana Saffari

53 THE SUPERFICIAL INFERIOR EPIGASTRIC ARTERY FASCIA FLAP IN RATS 3 INTRODUCTION It has been postulated that the application of either vascularized nerve grafts or a vascularized flap wrapped around the nerve graft will improve outcomes of nerve grafts in severely scarred tissue beds 1-6 . A well vascularized bed becomes more critical as length and caliber of a nerve graft increase 6 . The literature regarding pedicled fascial flaps in animals is scarce. The free superficial inferior epigastric artery (SIEA) flap in rats was first described in 1967 by Strauch andMurray 7 . This free tissue transfer could be designed in various sizes and has been applied in different investigational and training models (e.g. distal flap necrosis 8-12 , ischemia reperfusion injury 13-16 , and microvascular training 17 ). In the rat, no previously described facial flaps have been described or used to wrap around the sciatic nerve 18,19 . One study had been performed elevating a SIEA flap and evaluated for short term viability after seven days 19 . While this pedicled flap was demonstrated to be safe and avoids the potential risk of free flap failure (microvascular anastomosis complications), long-term viability was never assessed 19,20 . Another study described pedicled flaps to vascularize nerve grafts in an intratemporal facial nerve defect model and focused on histological outcomes 18 . The sciatic nerve defect model is a well-established model to investigate multiple outcomes varying from functional motor outcomes to histology 21-23 . A pedicled flap model in rats to provide vascularization to the nerve wound bed has not been described and requires validation prior to measurement of other outcomes. Therefore, the purpose of this study was to describe a reproducible surgical technique and determine long-term survivability for the pedicled superficial inferior epigastric artery fascial (SIEF) flap in the rat to meet requirement for a tunneled adipofascial flap to add vascularization to the sciatic nerve bed. METHODS Animals The study was approved by our Institutional Animal Care and Use Committee (IACUC A3348-18). Twenty male adult Lewis rats, weighing 250-300 grams (Envigo, USA) had a unilateral 10 mm sciatic nerve gap repaired with an decellularized processed nerve allograft 24 . Ten Sprague-Dawley rats (Envigo, Madison, WI, USA) weighing 250-300 grams served as major histocompatibility mismatch donors 25,26 . A 15-mm segment of