A biological cell shows not only passive behavior, but also active behavior. The behavior includes deformation, rotation, migration, division, exfoliation, differentiation, and fusion. A cell receives the mechanical stress in vivo. Several kinds of behavior of cells depend on the mechanical stress.A tissue consists of cells. Cells often make orientation in the tissue. The endothelial cells on the inner surface of the vessel wall are exposed to the blood flow. The wall shear stress is applied to the endothelial cells. The effects of shear flow on the endothelial cells are investigated in many studies. In the previous study with the vortex flow by the swinging plate in vitro, C2C12 (mouse myoblast cell line) made orientation perpendicular to the direction of the flow, although HUVEC (human umbilical vein endothelial cell) made orientation along the streamline of the flow.The orientation of each cell in the tissue depends on that of neighbor’s cell. To analyze the mechanism of making orientation of cells, the behavior of each cell in the shear flow field is quantitatively observed during cell-group formation. In the Poiseuille type of flow, the shear rate depends on the distance from the wall: highest at the wall. In the Couette type of flow, on the other hand, the shear rate is constant regardless of the distance from the wall. It takes several hours for adhesion of cells to the scaffold. The effect of the shear flow depends on the alignment of the cell. At division as well as at fusion, the alignment of the cell can change drastically. Variations can be made on the alignment of cells at the timing of division.In the present study, the effect of shear stress on myoblast has been investigated under the uniform shear flow in vitro. The culture medium was sandwiched with a constant gap between a lower stationary culture plate and an upper rotating parallel plate to make a Couette type of shear flow. The wall shear stress on the lower culture disk was controlled by the rotating speed of the upper disk. C2C12 was used in the test. After cultivation without flow for 24 hours for adhesion of cells on the lower plate, the wall shear stress was continuously applied on cells for 7 days in the incubator. The behavior of each cell was traced at the time-lapse image observed by an inverted phase contrast microscope placed in an incubator. The experimental results show that cells make both division and fusion under shear stress lower than 2 Pa. Interaction between divided cells decreases with the distance between cells. The smaller cell tends to follow the bigger cell related to the alignment. The cell with inactive migration tends to be exfoliated by the wall shear stress in the shear flow. The cell with active migration related to both the shape index and the velocity tends to be divided after rounding. The results of the experiment would be applied to control method to make engineered tissue by cells.

Tracings of Behavior of Myoblasts Cultured Under Couette Type of Shear Flow Between Parallel Disks

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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