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. 2018 Feb 8;118(4):2042–2079. doi: 10.1021/acs.chemrev.7b00317

Figure 5.

Figure 5

Using hydrodynamics to modulate the shear stress on cells. (A) Flow stimulation of bone cells with steady flow resulting in a wall shear stress of 2 N m–2, oscillating flow (−2 to 2 N m–2) and pulsatile flow (0 to 2 N m–2). Dynamic flows were applied with sinusoidal profiles of 0.5, 1.0, and 2.0 Hz. The stimulation of cells with pulsatile and steady flow (Pls, S) was significantly stronger than with oscillating (Osc) flow. (B) Multishear device containing ten channels of varying lengths (top). HUVECs were immunostained for intracellular and extracellular vWF factor (red), rhodamine phalloidon (green), and Hoechst (blue) after 20 h of perfusion under different shear flows. For shear stresses above 5 dyn cm–2 (0.5 Pa), cells exhibited significantly higher vWF secretion and were at least 30% smaller in size. (Scale bar: 50 μm). (C) A multishear microfluidic device for quantitative analysis of calcium dynamics in osteoblasts. (i) Four different shear levels (0.3, 0.6, 1.2, and 3 dyn cm–2) were exerted on osteoblasts to study the cytosolic calcium concentration Ca2+ dynamics. (ii and iii) The cytosolic calcium concentration increased with shear stress from 0.3 to 3 dyn cm–2 (0.03 to 0.30 Pa); the response to shear was delayed with an activation threshold between 0.3 and 0.6 dyn cm–2 (0.03 and 0.06 Pa). (D) Effect of flow rate and shear level on the shape and orientation of endothelial cells in a straight microfluidic channel. At high flow rates (large pump, high shear) and flow exposure times, the HDMECs tend to align and elongate significantly (decreasing Supporting Information) in the direction of flow (decreased angle of alignment). In contrast, at low flow rates (small pump, low shear), the flow and flow exposure time do not affect the cell shape and orientation. (A) Adapted with permission from ref (83). Copyright 1998 Elsevier. (B) Adapted with permission from ref (85). Copyright 2009 the Royal Society of Chemistry. (C) Adapted with permission from ref (87). Copyright 2011 Elsevier. (D) Adapted from ref (88). Copyright 2005 the American Chemical Society.