Matrix Metalloproteinase-2 and −9 Differentially Regulate Smooth Muscle Cell Migration and Cell-Mediated Collagen Organization

Abstract

Objectives— Smooth muscle cells (SMCs) produce both matrix metalloproteinase (MMP)-2 and MMP-9, enzymes with similar in vitro matrix degrading abilities. We compared the specific contributions of these enzymes to SMC-matrix interactions in vitro and in vivo. Methods and Results— Using genetic models of deficiency, we investigated MMP-2 and MMP-9 roles in SMC migration in vivo in the formation of intimal hyperplasia and in vitro. In addition, we investigated potential effects of MMP-2 and MMP-9 genetic deficiency on compaction and assembly of collagen by SMCs. Conclusions— MMP-2 and MMP-9 genetic deficiency decreased by 81% and 65%, respectively (PPP<0.01), indicating that SMCs may use MMP-9 as a bridge between the cell surface and matrix. Furthermore, we found that the hyaluronan receptor, CD44, assists in attachment and utilization of MMP-9 by SMCs. Understanding the specific roles of these MMPs, generally thought to be similar, could improve the design of therapeutic interventions aimed at controlling vascular remodeling.