The present invention discloses use of one or more MicroRNA genes selected from miRNAs of Family Let-7, miR-21 or miR-222 in the construction of tissue engineered nerves and in the repair of peripheral nerve defects. An outer and/or internal surface or pores of a tissue engineered nerve graft are coated or adsorbed with polymeric nanomicrospheres carrying a Let-7 family miRNA inhibitor, miR-21, or miR-222, or a mimetic thereof, wherein the polymeric material is composed of biocompatible fibronectin and heparin. In the present invention, the regeneration of peripheral nerves and the construction of tissue engineered nerves are promoted by regulating the expression of MicroRNA genes which can effectively promote the proliferation of primary Schwann cells cultured in vitro and have an anti-apoptotic effect on neuronal cells. In-vivo test proves that bridging of the tissue engineered nerve graft can facilitate the regeneration of peripheral nerves, thus being useful in the treatment of peripheral nerve injury.
