title: Quantification of local matrix deformations and mechanical properties during capillary morphogenesis in 3D.
abstract: Reciprocal mechanical interactions between cells and the extracellular matrix (ECM) are thought to play important instructive roles in branching morphogenesis. However, most studies to date have failed to characterize these interactions on a length scale relevant to cells, especially in three-dimensional (3D) matrices. Here we utilized two complementary methods, spatio-temporal image correlation spectroscopy (STICS) and laser optical tweezers-based active microrheology (AMR), to quantify endothelial cell (EC)-mediated deformations of individual ECM elements and the local ECM mechanical properties, respectively, during the process of capillary morphogenesis in a 3D cell culture model. In experiments in which the ECM density was systematically varied, STICS revealed that the rate at which ECs deformed individual ECM fibers on the microscale positively correlated with capillary sprouting on the macroscale. ECs expressing constitutively active V14-RhoA displaced individual matrix fibers at significantly faster rates and displayed enhanced capillary sprouting relative to wild-type cells, while those expressing dominant-negative N19-RhoA behaved in an opposite fashion. In parallel, AMR revealed a local stiffening of the ECM proximal to the tips of sprouting ECs. By quantifying the dynamic physical properties of the cell-ECM interface in both space and time, we identified a correlation linking ECM deformation rates and local ECM stiffening at the microscale with capillary morphogenesis at the macroscale.
authors.affiliation: Biomedical Engineering Department, Natural Sciences II, Room 3201, University of California, Irvine, Irvine, CA 92697-2715, USA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Kniazeva
authors.forename: John W
authors.initials: JW
authors.lastname: Weidling
authors.forename: Rahul
authors.initials: R
authors.lastname: Singh
authors.forename: Elliot L
authors.initials: EL
authors.lastname: Botvinick
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Digman
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Putnam
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D055119:Elastic Modulus / Q000502:physiology; D005109:Extracellular Matrix / Q000737:chemistry / Q000502:physiology*; D005337:Fibrin / Q000737:chemistry / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D018613:Microscopy, Confocal / Q000379:methods; D018919:Neovascularization, Physiologic / Q000502:physiology*; D052898:Optical Tweezers; D012212:Rheology / Q000379:methods; D014162:Transfection; D014783:Viscosity; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D020100:Hydrogels; C066737:RHOA protein, human; D005337:Fibrin; D020742:rhoA GTP-Binding Protein