Introduction: Although many tubular systems for peripheral nerve repair have been reported, a successful reconstruction utilizing adult Schwann cells (SCs) without conduit systems has not been reported. The use of artificial conduits results in inflammatory reactions and avascular environments thus induces the low survivability of donated SCs. The purpose of this study is to promote nerve regeneration across a nerve gap, using a tissue-engineered matrix guide containing a high density of viable SCs without foreign tubular materials in vivo. Materials and Methods: SCs were isolated from adult Fisher rat sciatic nerves and cultured for 4 weeks. The isolated SCs were labeled with GFP adenovirus system and seeded into the synthetic constructs of Polyglycolic acid-Pluronic F127. This construct was implanted into the back of a nude mouse to create a tissue-engineered matrix guide for 6 weeks and was harvested for implantation. Next, these tissue-engineered guides with viable SCs were implanted into one-centimeter gaps of sciatic nerve lesions in Fisher rats (N=4), and compared to the autograft group (N=4), and to the use of silicone conduit group (N=4). All rats were injected with the immunosuppressive drug daily for 4 weeks to prevent inflammatory reactions. After 8 weeks, motor function of the leg was evaluated. Fluorogold axon tracer was injected at a distal site to the lesion before cross and sagittal sections were analyzed. Results: The implants retained their structure with some adhesion formation. Histological study demonstrated large numbers of viable SCs with no identifiable remnants of scaffold within the tissue-engineered matrix guides and GFP positive SCs through the implants in vivo. Fluorogold were detected along the axons in the sagittal sections. No significant difference was observed in motor function compared to the autograft. Discussion: The use of a number of SCs within their own extracellular matrix is sufficient to enable neuronal growth across a nerve gap in the absence of a conduit. This may be dependent upon a good vascular supply from the surrounding tissues as well as neurotrophic factors from the implanted SCs. Nevertheless of the problem regarding to a long-term cell-culture, this novel strategy represents a potential insight into the peripheral nerve reconstruction for future clinical applications.