A formulation including injectable biodegradable nanospheres and/or microspheres as a delivery system for chondroitinase ABC (cABC) or a functional derivative of cABC to treat acute and chronic spinal chord injury in a mammal having the same is provided. The biodegradable nanosphere/microsphere formulation releases cABC or a functional derivative of cABC in a time-released manner at the site of the spinal cord injury. cABC infusion can promote axon regrowth and some behavioral recovery. The nanospheres and/or microspheres provided herein include cABC or a functional derivative of cABC loaded within and/or on a biodegradable polymer matrix. In some embodiments of the present invention, the surface of the biodegradable polymer matrix can be modified to target a specific scar site. In addition to providing a nanosphere formulation that include polymeric incorporated cABC, a method of treating a mammal having a spinal cord injury is also provided.