title: Endothelial cell migration in stable gradients of vascular endothelial growth factor A and fibroblast growth factor 2: effects on chemotaxis and chemokinesis.
abstract: Gradients of secreted signaling proteins guide growing blood vessels during both normal and pathological angiogenesis. However, the mechanisms by which endothelial cells integrate and respond to graded distributions of chemotactic factors are still poorly understood. We have in this study investigated endothelial cell migration in response to hill-shaped gradients of vascular endothelial growth factor A (VEGFA) and fibroblast growth factor 2 (FGF2) using a novel microfluidic chemotaxis chamber (MCC). Cell migration was scored at the level of individual cells using time-lapse microscopy. A stable gradient of VEGFA165 ranging from 0 to 50 ng/ml over a distance of 400 microm was shown to strongly induce chemotaxis of endothelial cells of different vascular origin. VEGFA121, unable to bind proteoglycan and neuropilin coreceptors, was also shown to induce chemotaxis in this setup. Furthermore, a gradient of FGF2 was able to attract venular but not arterial endothelial cells, albeit less efficiently than VEGFA165. Notably, constant levels of VEGFA165, but not of FGF2, were shown to efficiently reduce chemokinesis. Systematic exploration of different gradient shapes led to the identification of a minimal gradient steepness required for efficient cell guidance. Finally, analysis of cell migration in different regions of the applied gradients showed that chemotaxis is reduced when cells reach the high end of the gradient. Our findings suggest that chemotactic growth factor gradients may instruct endothelial cells to shift toward a nonmigratory phenotype when approaching the growth factor source.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
authors.forename: Irmeli
authors.initials: I
authors.lastname: Barkefors
authors.forename: Sébastien
authors.initials: S
authors.lastname: Le Jan
authors.forename: Lars
authors.initials: L
authors.lastname: Jakobsson
authors.forename: Eduar
authors.initials: E
authors.lastname: Hejll
authors.forename: Gustav
authors.initials: G
authors.lastname: Carlson
authors.forename: Henrik
authors.initials: H
authors.lastname: Johansson
authors.forename: Jonas
authors.initials: J
authors.lastname: Jarvius
authors.forename: Jeong Won
authors.initials: JW
authors.lastname: Park
authors.forename: Noo
authors.initials: N
authors.lastname: Li Jeon
authors.forename: Johan
authors.initials: J
authors.lastname: Kreuger
mesh_terms: D001158:Arteries / Q000166:cytology; D002465:Cell Movement; D002478:Cells, Cultured; D002633:Chemotaxis; D042783:Endothelial Cells / Q000166:cytology*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008853:Microscopy; D008954:Models, Biological; D010641:Phenotype; D020033:Protein Isoforms; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D020033:Protein Isoforms; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2