title: Monocyte recruitment to endothelial cells in response to oscillatory shear stress.
abstract: Leukocyte recruitment to endothelial cells is a critical event in inflammatory responses. The spatial, temporal gradients of shear stress, topology, and outcome of cellular interactions that underlie these responses have so far been inferred from static imaging of tissue sections or studies of statically cultured cells. In this report, we developed micro-electromechanical systems (MEMS) sensors, comparable to a single endothelial cell (EC) in size, to link real-time shear stress with monocyte/EC binding kinetics in a complex flow environment, simulating the moving and unsteady separation point at the arterial bifurcation with high spatial and temporal resolution. In response to oscillatory shear stress (tau) at +/- 2.6 dyn/cm2 at a time-averaged shear stress (tau(ave))=0 and 0.5 Hz, individual monocytes displayed unique to-and-fro trajectories undergoing rolling, binding, and dissociation with other monocyte, followed by solid adhesion on EC. Our study quantified individual monocyte/EC binding kinetics in terms of displacement and velocity profiles. Oscillatory flow induces up-regulation of adhesion molecules and cytokines to mediate monocyte/EC interactions over a dynamic range of shear stress +/- 2.6 dyn/cm2 (P=0.50, n=10).
authors.affiliation: Department of Biomedical Engineering and Division of Cardiovascular Medicine, USC School of Engineering and Keck School of Medicine, Los Angeles 90089-1451, USA. hsiai@usc.edu
authors.forename: Tzung K
authors.initials: TK
authors.lastname: Hsiai
authors.forename: Sung K
authors.initials: SK
authors.lastname: Cho
authors.forename: Pak K
authors.initials: PK
authors.lastname: Wong
authors.forename: Mike
authors.initials: M
authors.lastname: Ing
authors.forename: Adler
authors.initials: A
authors.lastname: Salazar
authors.forename: Alex
authors.initials: A
authors.lastname: Sevanian
authors.forename: Mohamad
authors.initials: M
authors.lastname: Navab
authors.forename: Linda L
authors.initials: LL
authors.lastname: Demer
authors.forename: Chih-Ming
authors.initials: CM
authors.lastname: Ho
mesh_terms: D015374:Biosensing Techniques; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D009000:Monocytes / Q000166:cytology / Q000276:immunology*; D019007:P-Selectin / Q000235:genetics / Q000378:metabolism; D010507:Periodicity; D012333:RNA, Messenger / Q000378:metabolism; D012212:Rheology; D013314:Stress, Mechanical
chemical_list: D018932:Chemokine CCL2; D019007:P-Selectin; D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1