Modeling stretch-dependent collagen fiber density

Abstract

Collagen is a load bearing constituent in many soft tissues, which undergoes remodeling processes that are mediated by mechanical stimuli. Experiments suggest that fiber stretching tends to suppress the enzymatic degradation of the collagen fibers. This article presents a mechanical model that describes how this impacts overall collagen density. It specifically accounts for processes that involve ongoing change to the local stretch as the remodeling incorporates new fibers into the overall collagen network. The governing integral expression allows calculation of the local fiber density as determined by a specified deformation without the need to know or to specify either the stiffness or the force loading of the material under consideration. Fiber density homeostasis is disrupted by sudden changes in stretch, and regain of homeostasis is characterized by three characteristic times and hence two dimensionless groups.