Provided herein are sutures for use in a procedure applied to tissue, and methods for forming such sutures. Some sutures include bi-directional retainers, each of which can be deployed in two directions, but once deployed in one direction, resist motion in the opposite direction. Other sutures include uni-directional retainers that are conical in shape, and include tissue engaging protrusions that extend from edges and/or angled walls of the conical retainers.
