Role and function of matrix metalloproteinases in the differentiation and biological characterization of mesenchymal stem cells

Matrix metalloproteinases, known as matrixins, are Ca/Zn-dependent endoproteinases involved in a wide variety of developmental and disease-associated processes, proving to be crucial protagonists in many physiological and pathological mechanisms. The ability of MMPs to alter, by limited proteolysis and through the fine control of tissue specific inhibitors, the activity or function of numerous proteins, enzymes and receptors suggests their involvement in various important cellular functions also during development. In this review we focus on the differentiation of mesenchymal stem cells (such as the myoblastic, osteoblastic, chondroblastic, neural and apidoblastic lineages) and the possible if unexpected biological significance of MMPs in its regulation. The MMP system has been implicated in several differentiation events suggesting it in mediating the proliferative and pro-differentiating effect of matrixin proteolytic cascade. We summarize these regulatory effects of MMPs on the differentiation of mesenchymal stem cells and hypothesize on the function of MMPs in stem cell differentiation processes.