Micropatterned Structural Control Suppresses Mechanotaxis of Endothelial Cells
Xiefan Lin 1 and Brian P. Helmke 1*
1 University of Virginia
* To whom correspondence should be addressed. E-mail: helmke{at}virginia.edu.
Submitted on December 12, 2007
Revised on January 30, 2008
Accepted on 9 June 2008
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Abstract |
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Vascular endothelial cell migration is critical in many physiological processes including wound healing and stent endothelialization. To determine how pre-existing cell morphology influences cell migration under fluid shear stress, endothelial cells were preset in an elongated morphology on micropatterned substrates, and unidirectional shear stress was applied either parallel or perpendicular to the cell elongation axis. On micropatterned 20-µm lines, cells exhibited an elongated morphology with stress fibers and focal adhesion sites aligned parallel to the lines. On 115-µm lines, cell morphology varied as a function of distance from the line edge. Unidirectional shear stress caused unpatterned cells in a confluent monolayer to exhibit triphasic mechanotaxis behavior. During the first 3 h, cell migration speed increased in a direction antiparallel to the shear stress direction. Migration speed then slowed and direction became spatially heterogeneous. Starting 11-12 h after the onset of shear stress, the unpatterned cells migrated primarily in the downstream direction, and migration speed increased significantly. In contrast, mechanotaxis was suppressed after onset of shear stress in cells on micropatterned lines during the same time period, both for cases of parallel and perpendicular flow. The directional persistence time was much longer for cells on the micropatterned lines, and it decreased significantly after flow onset. Migration trajectories were highly correlated among micropatterned cells within a 3-cell neighborhood, and shear stress disrupted this spatially correlated migration behavior. Thus, presetting structural morphology may interfere with mechanisms of sensing local physical cues, critical for establishing mechanotaxis in response to hemodynamic shear stress.
Key Words:
cell migration, directional persistence, mechanotransduction, shear stress
