title: A novel in vitro model for microvasculature reveals regulation of circumferential ECM organization by curvature.
abstract: In microvascular vessels, endothelial cells are aligned longitudinally whereas several components of the extracellular matrix (ECM) are organized circumferentially. While current three-dimensional (3D) in vitro models for microvasculature have allowed the study of ECM-regulated tubulogenesis, they have limited control over topographical cues presented by the ECM and impart a barrier for the high-resolution and dynamic study of multicellular and extracellular organization. Here we exploit a 3D fibrin microfiber scaffold to develop a novel in vitro model of the microvasculature that recapitulates endothelial alignment and ECM deposition in a setting that also allows the sequential co-culture of mural cells. We show that the microfibers' nanotopography induces longitudinal adhesion and alignment of endothelial colony-forming cells (ECFCs), and that these deposit circumferentially organized ECM. We found that ECM wrapping on the microfibers is independent of ECFCs' actin and microtubule organization, but it is dependent on the curvature of the microfiber. Microfibers with smaller diameters (100-400 µm) guided circumferential ECM deposition, whereas microfibers with larger diameters (450 µm) failed to support wrapping ECM. Finally, we demonstrate that vascular smooth muscle cells attached on ECFC-seeded microfibers, depositing collagen I and elastin. Collectively, we establish a novel in vitro model for the sequential control and study of microvasculature development and reveal the unprecedented role of the endothelium in organized ECM deposition regulated by the microfiber curvature.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Johns Hopkins Physical Sciences-Oncology Center and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Sebastian F
authors.initials: SF
authors.lastname: Barreto-Ortiz
authors.forename: Shuming
authors.initials: S
authors.lastname: Zhang
authors.forename: Matthew
authors.initials: M
authors.lastname: Davenport
authors.forename: Jamie
authors.initials: J
authors.lastname: Fradkin
authors.forename: Brian
authors.initials: B
authors.lastname: Ginn
authors.forename: Hai-Quan
authors.initials: HQ
authors.lastname: Mao
authors.forename: Sharon
authors.initials: S
authors.lastname: Gerecht
mesh_terms: D002448:Cell Adhesion; D018929:Cell Culture Techniques; D042783:Endothelial Cells / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D005337:Fibrin; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D066298:In Vitro Techniques; D055806:Microvessels / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism; D054457:Tissue Scaffolds
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005337:Fibrin