It is therefore proposed that enrichment the degree of vascularization in nerve scaffolds may be of significant importance in enhancing axonal regeneration and functional recovery. The omentum, the largest peritoneal fold hanging down from the stomach and covering most of the intestines, is a physiologically dynamic tissue and possesses a high vascularization capacity. Experimentally and clinically, omentum has been widely used as a vascularizing agent in ischemic extremity coverage, cardiothoracic reconstruction, brain and spinal cord revascularization, and bone healing. Also, studies have shown that omentum significantly promotes vascularization and maturation of tissue-engineered constructs to which it is applied. In addition, due to the combined ability of angiogenesis and neurotropism, omentum has been used as a viable option for the treatment of the re-operated median nerve following revision carpal tunnel surgery. Nerve defects that bridged by omentum-wrapped nerve autografts showed earlier revascularization and better axonal regeneration compared to those bridged by nerve autografts alone. However, combined application of omentum and tissue-engineered nerve scaffolds on nerve regeneration has been rarely investigated by far. In the present study, a collagen-chitosan scaffold with longitudinal oriented micro-channels was fabricated, and was then used to bridge a 15-mm-long sciatic nerve defect in rats. For supporting formation of blood vessels network and nourishing axonal outgrowth across the nerve scaffold, autologous omentum was harvested and wrapped around the scaffold, including the proximal and distal segments of the recipient nerve. The effect of omentum-wrapped scaffold on axonal regeneration and functional recovery was evaluated by both morphological analysis and functional assessment, and the expressions of vascularization and regeneration related genes were evaluated by Western blotting. In the present study, we investigated the effect of the omentumwrapped L-CCH scaffold on axonal regeneration and functional recovery in bridging a 15-mm-long sciatic nerve defect in rats. Our study showed that omentum-wrapped scaffold significantly enhanced axonal regeneration and functional recovery. In addition, application of omentum was able to support formation of blood vessels network and significantly increased the protein levels of VEGF, BDNF and NGF within the scaffold in the early weeks after surgery. These findings indicate that the omentumwrapped scaffold is capable of vascularizing nerve scaffold which might be able to nourish axonal outgrowth, hence improving axonal regeneration and motor functional recovery. Local vascular supply is essential in the regenerative environment of injured peripheral nerves, while neovascularization may further enhance axon-SC association and play an important role during the process of nerve regeneration. Therefore, vascularization of nerve scaffolds is crucial for axonal outgrowth and Nutlin-3 restoration of functional recovery. In the present study, the omentum-wrapping significantly enhanced axonal regeneration through the whole length of the L-CCH scaffold. Massive myelinated axons were exhibited with an even distribution in the proximal, middle, and distal portions of nerve grafts in the LCCH+OW group at 4, 8 and 12 weeks after surgery.