title: Bone marrow stromal cells stimulate an angiogenic program that requires endothelial MT1-MMP.
abstract: Bone marrow-derived stromal/stem cells (BMSCs) have recently been characterized as mediators of tissue regeneration after injury. In addition to preventing fibrosis at the wound site, BMSCs elicit an angiogenic response within the fibrin matrix. The mechanistic interactions between BMSCs and invading endothelial cells (ECs) during this process are not fully understood. Using a three-dimensional, fibrin-based angiogenesis model, we sought to investigate the proteolytic mechanisms by which BMSCs promote vessel morphogenesis. We find that BMSC-mediated vessel formation depends on the proteolytic ability of membrane type 1-matrix metalloproteinase (MT1-MMP). Knockdown of the protease results in a small network of vessels with enlarged lumens. Contrastingly, vessel morphogenesis is unaffected by the knockdown of MMP-2 and MMP-9. Furthermore, we find that BMSC-mediated vessel morphogenesis in vivo follows mechanisms similar to what we observe in vitro. Subcutaneous, cellular fibrin implants in C.B-17/SCID mice form aberrant vasculature when MMPs are inhibited with a broad-spectrum chemical inhibitor, and a very minimal amount of vessels when MT1-MMP proteolytic activity is interrupted in ECs. Other studies have debated the necessity of MT1-MMP in the context of vessel invasion in fibrin, but this study clearly demonstrates its requirement in BMSC-mediated angiogenesis.
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA.
authors.forename: Suraj
authors.initials: S
authors.lastname: Kachgal
authors.forename: Bita
authors.initials: B
authors.lastname: Carrion
authors.forename: Isaac A
authors.initials: IA
authors.lastname: Janson
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Putnam
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism / Q000502:physiology; D002450:Cell Communication; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005337:Fibrin; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000235:genetics / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology; D051379:Mice; D016513:Mice, SCID; D018919:Neovascularization, Physiologic / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D061965:Matrix Metalloproteinase Inhibitors; D005337:Fibrin; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D053511:Matrix Metalloproteinase 14