A cross sectional view of a cone and plate rheometer. The cone rotates about the axis and applies a WSS to the plate surface (cultured ECs) via the rotating fluid between the cone and plate.
A schematic of the ten cellular substrates. Eight of the substrates (1–8) are exposed to WSS and a range of THS. The six double sided arrows indicate the substrate stretch directions. Two control substrates (9 and 10) are contained in two compartments in the main container of the bioreactor submerged in the same media as all the other cellular samples, but substrates 9 and 10 are subjected to no mechanical stimuli.
(A) A schematic of the bioreactor design. A cable and pulley system controls the strain applied to each of the six flexible silicone substrates. The variance in the pulleys tier diameters creates three different magnitudes of cable linear displacement and cellular substrate strain magnitude. (B) A picture of the bioreactor placed inside an incubator. The incubator controls the testing temperature, humidity, and atmosphere’s levels.
Schematic diagram of the fluid region present between the plate and cone surfaces. The cone has a flattened tip with a diameter of . The volume also includes the two sets of four indents; a set at radial position ( from the plate center point) and the second set placed at a radial position ( from the center point). Model (B), with the indent at , and model (C), with the indent at , are 45° slices of the entire model.
This image shows the control volume (the region in which the flow is modeled) to mesh all the CFD models. This control volume is represented as an inflation boundary layer. In all three models, the regions adjacent to the plate and indent surfaces were meshed with fine prismatic elements and the remaining volume was meshed with tetrahedral elements. An inflation boundary (five layers, 1.2 expansion factor, and a first layer height of ) was used to generate this mesh. Periodic boundary conditions (axisymmetry about the axis) were also applied to the inlet and outlet surfaces.
(a) The computed WSS present on the plate and inner plane ( square) of model (B). The cone surface was given a constant angular velocity of about the axis. By reducing the observation region , the flow disturbances (edge effects) have been removed and the WSS is more consistent throughout the remaining area, as shown in (b).
Plot of WSS values vs angular velocity for model (A) (plate surface WSS), the indent inner plane area averaged WSS for both models (B) and (C), and the analytical WSS solution for a range of cone angular velocities.
(Color online) This image shows a monolayer of HUVECs after in the bioreactor seeded on a fibronectin coated silicone substrate. The cells were H&E stained and photographed at magnification.
(Color online) Three images of a monolayer of HUVECs, which were grown on fibronectin coated silicone substrates. The cells were exposed to a low steady WSS and cyclical THS (0–12)%. The cells were H&E stained and photographed at three different magnifications (, , and ). Note that the white and black arrows indicate the THS and WSS directions, respectively.
Mechanical stimulus applied to each substrate (see Fig. 2).
A list of materials used in the bioreactor. All the materials are inert and nontoxic.
Alamar Blue assay results for cellular samples placed in the bioreactor for time periods up to ; the data are presented as a mean percentage of three tests and the standard deviation of these tests.
Measurement of growth medium levels during the strain experiment.
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