Non-fibrillar collagens: key mediators of post-infarction cardiac remodeling?

Cardiac remodeling is accelerated during pathological conditions and several anabolic and catabolic regulators work in concert to repair the myocardium and maintain its functionality. The fibroblasts play a major role in this process via collagen deposition as well as supplying the degradative matrix metalloproteinases. During the more acute responses to a myocardial infarction (MI) the heart relies on a more aggressive wound healing sequence that includes the myofibroblasts, specialized secretory cells necessary for infarct scar formation and thus, rescue of the myocardium. The activated fibroblasts and myofibroblasts deposit large amounts of fibrillar collagen during the post-MI wound healing phase, type I and III collagen are the most abundant collagens in the heart and they maintain the structural integrity under normal and disease states. While collagen I and III have been the traditional focus of the myocardial matrix, recent studies have suggested that the non-fibrillar collagens (types IV and VI) are also deposited during pathological wound healing and may play key roles in myofibroblast differentiation and organization of the fibrillar collagen network. This review highlights the potential roles of the non-fibrillar collagens and how they work in concert with the fibrillar collagens in mediating myocardial remodeling.