Active tissue augmenting agents, compositions and methods for use are disclosed. In a typical embodiment, the active augmenting agents of the invention can be used to form an artificial sphincter around a lumen of a human or animal body. In one embodiment, the active augmenting agent comprises magnitizable particles which can provide occlusion of a lumen, such as the urethral lumen, by circumferential attraction of the injected material toward the center of the lumen by the inherent magnetic flux field created from the magnetic dipoles of the magnetic particles.