A carrier matrix may be delivered to a target position within a patient in a minimally invasive manner by first cutting a collagen sponge sheet into a plurality of relatively small pieces. These pieces are sized so that, when wet, they are capable of flowing through a cannula and/or reduced-diameter syringe tip. The pieces are placed into a syringe and wetted, say with a morphogenic solution, and optionally mixed with a bulking material, which is similarly sized to fit through the cannula. The thoroughly mixed and wetted product forms a viscous aggregate which may then be injected into the patient at the target site.