The present invention involves the fabrication and use of biocompatible polymers that are injected percutaneously into the inner portion of a defective region of a spinal disc and swell or expand or subsequently cure in situ to form a disc nucleus prosthesis. The polymers may be synthetic or natural (e.g., collagen), and may be provided in forms including, but not limited to hydrogels, compressible foams, cords, balloons, etc. Subsequent to injection into a target space or void within the disc, one or more cell binding agents, growth factors, and/or drugs on or within the cured polymer then interact with the remaining portion of the disc to support tissue ingrowth and to achieve a higher probability of biological mimicking.