Percityes catalyze endothelial cell basment membrane formation during vascular morphogenesis [abstract]
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Recent work in the lab has demonstrated the requirement of MT1-MMP in the generation of proteolytic spaces within collagen I matrices, which we have termed vascular guidance tunnels. These tunnels are formed as a consequence of EC lumen and tube formation. There is marked pericyte recruitment to the endothelium and to within tunnel spaces, allowing for direct ECpericyte interactions. Over time, these interactions lead to marked deposition of basement membrane proteins and vascular stabilization. Non-detergent immunostaining analysis, directed at revealing extracellular proteins only, has revealed significant deposition of fibronectin, laminin, collagen IV, nidogen 1/2, and perlecan only when both EC and pericytes are present within the culture. These data are consistent both with human umbilical vein ECs and human dermal microvascular ECs, as well as with both bovine and human pericytes. Furthermore, PCR analysis and integrin blocking data suggests a role for various integin-matrix interactions throughout the morphogenic assembly process. Initially, EC assembly is controlled predominantly by 2 1 with and without pericytes present, but as assembly continues in ECpericyte cocultures the requirement of 2 1 is diminished while other integrin chains, including the laminin receptors 3 1 and 6 1 and the fibronectin receptor 5 1, have marked affects of EC tube morphology suggesting matrix remodeling over time. Thus, pericytes catalyze basement membrane matrix assembly following their recruitment to EC lined tubes during vascular morphogenic events.