title: Endothelial Surface Protrusion by a Point Force.
abstract: During leukocyte rolling on the endothelium, surface protrusion and membrane tether extraction occur consecutively on leukocytes. Both surface protrusion and tether extraction of leukocytes stabilize leukocyte rolling. Tethers can also be extracted from endothelial cells (ECs), but surface protrusion of ECs has never been confirmed to exist. In this study, we examined EC surface protrusion with the micropipette aspiration technique. We found that, like leukocytes, surface protrusion on an EC did exist when a point force was imposed. Both the protrusional stiffness and the crossover force of EC surface protrusion were dependent on the force loading rate and the cytoskeletal integrity, but neither of them was dependent on tumor necrosis factor α stimulation. Temperature (37°C) affected the protrusional stiffness only at small force loading rates. When a neutrophil was employed to directly impose the pulling force on the EC, simultaneous surface protrusion from both cells occurred, and it can be modeled as two springs connected in series, although the spring constants should be adjusted according to the force loading rate. Therefore, EC surface protrusion is an important aspect of leukocyte rolling, and it should not be ignored when leukocyte rolling stability is studied systematically.
authors.affiliation: Department of Biomedical Engineering, Washington University, Saint Louis, Missouri.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, Washington University, Saint Louis, Missouri.
authors.forename: Lan
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Biomedical Engineering, Washington University, Saint Louis, Missouri. Electronic address: shao@wustl.edu.
authors.forename: Jin-Yu
authors.initials: JY
authors.lastname: Shao
mesh_terms: D001696:Biomechanical Phenomena / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008863:Microspheres; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011312:Pressure; D013696:Temperature; D053778:Thiazolidines / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014741:Video Recording
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D053778:Thiazolidines; D014409:Tumor Necrosis Factor-alpha; C037068:latrunculin B