Profile and Localization of Matrix Metalloproteinases (MMPs) and their Tissue Inhibitors (TIMPs) in Human Heart Valves
Sally A. Dreger PhD, Patricia M. Taylor PhD, Sean P. Allen PhD, Magdi H. Yacoub FRS

Tissue turnover is one of many factors involved in the operational longevity of heart valves. Matrix metalloproteinases (MMPs) are proteolytic enzymes involved in matrix remodeling in several tissues. The study aim was to determine the expression of MMPs and their tissue inhibitors (TIMPs) in healthy human heart valve leaflets, to show the topographical location of these enzymes, and examine the role of MMPs and TIMPs in tissue regeneration. Immunohistochemical staining was performed on paraffin sections of human valve leaflets using a panel of antibodies against MMPs, TIMPs and phenotypic markers CD31 (endothelial cells), smooth muscle alpha-actin and CD68 (macrophages). Human cardiac valves were shown to have a specific pattern of expression of MMPs and TIMPs that appears to vary in different heart valves.