Micropatterned Structural Control Suppresses Mechanotaxis of Endothelial Cells

Abstract

Vascular endothelial cell migration is critical in many physiological processes including wound healing and stent endothelialization. To determine how preexisting 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-microm lines, cells exhibited an elongated morphology with stress fibers and focal adhesion sites aligned parallel to the lines. On 115-microm 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 the onset of shear stress in cells on micropatterned lines during the same time period, for the cases of both 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 three-cell neighborhood, and shear stress disrupted this spatially correlated migration behavior. Thus, presetting structural morphology may interfere with mechanisms of sensing local physical cues, which are critical for establishing mechanotaxis in response to hemodynamic shear stress.

Micro- and Nanotechnology in Tissue Engineering

“…Another study went deeper into the analysis of how endothelial cells respond to the shear stress caused by the blood flow. This study helped in understanding the process of endothelial mechanotransduction, suggesting that the design of new substitutes for vascular TE should not only consider the material and biological cues, but also the hemodynamic profiles, in order to improve tissue integration and regeneration [74]. An essential parameter in vascular TE is the recruitment of cells from the blood to the vascular wall in a situation of thrombosis or inflammation.…”

Regulation of Adhesion Mechanosignalling by Fibronectin Matrix Structure

“…[11,12,13] In the reorientation phase, the cell establishes planar cell polarity in the flow direction, stress fiber assembly and migration speed increase, and the cell elongates in the flow direction. [14,15] Once the cell has aligned, migration speed stabilizes and junctions are reestablished. [12,14] There is some variation in reports of how long alignment takes to complete.…”

“…[14,15] Once the cell has aligned, migration speed stabilizes and junctions are reestablished. [12,14] There is some variation in reports of how long alignment takes to complete. There is some evidence that shear stress profile variables, such as magnitude and slew rate in pulsatile flow, can regulate speed of alignment.…”

“…[14] Micropatterning can also control other cell behaviors, as evidenced by the combined effect of micropatterns and shear stress on endothelial apoptosis. Increased apoptosis is induced by limiting cell adhesion to narrow micropatterned lines; however, this effect can be countered by shear stress-dependent Rho activation and FAK phosphorylation.…”

“…To achieve sparse surface coverage, cells were plated at 5,000-10,000 cells/cm 2 and allowed to adhere overnight (14)(15)(16)(17)(18) hours) before application of shear stress. For experiments that required serum starvation, sparse BAEC were plated in complete growth media for 4-6 hours and allowed to adhere, then starved in media containing 0.5% NCS for 12 hours before application of shear stress.…”