Matrix metalloproteinase regulation of sphingosine-1-phosphate-induced angiogenic properties of bone marrow stromal cells

Abstract

Bone marrow-derived stromal cells (MSC) are able to acquire histological and immunophenotypic characteristics consistent with endothelial cells (EC). In this study we examined the effect of sphingosine-1-phosphate (S1P), a platelet-derived bioactive lysophospholipid that is believed to specifically stimulate EC migration and tube formation, on the angiogenic properties of MSC. MSC were isolated from murine bone marrow and cultured in the presence of diverse angiogenic growth factors. Using a chemotaxis chamber and Matrigel tubulogenesis assay, we measured the extent of MSC migration and capillary-like structure formation. Western blots and zymography were used to assess the levels and activation states of soluble and membrane-bound matrix metalloproteinase (MMP). We found that S1P strongly induced MSC migration and in vitro capillary-like structure formation. Ilomastat, a broad-spectrum MMP inhibitor, antagonized several angiogenic and S1P-mediated events in MSC. These included 1) the inhibition of S1P-induced tube formation, 2) the inhibition of concanavalin-A (Con-A)-mediated proMMP-2 activation, and 3) the inhibition of S1P- and Con-A-induced caspase-3 activity. Moreover, S1P induced membrane type-1 (MT1)-MMP mRNA and protein expression, but paradoxically antagonized its cell surface proteolytic processing. In addition, anti-angiogenic agents such as Ilomastat, Neovastat, and green tea polyphenol epigallocatechin-3-gallate antagonized the S1P-induced migration of MSC as well as that of transfected COS-7 cells overexpressing the recombinant receptor for S1P, EDG-1. Collectively, our results indicate a crucial role for S1P/EDG-1-mediated angiogenic and survival events in the regulation of microvascular network remodeling by MSC, and may provide a new molecular link between hemostasis and angiogenesis processes.