Shear-flow cytometry

Cone-and-Plate Viscometery under Shear-Flow Cytometry... 

Fig. 1. Quantification of shear-induced platelet aggregation by flow cytometry. Panel A corresponds to an unsheared blood specimen. Panel B corresponds to a blood specimen that has been subjected to a pathologically high level of shear stress for 30 sec. As can be seen in the figure there are three distinct cell populations. The upper population consists of platelets and platelet aggregates. The rbcs-plts population corresponds to platelets associated with erythrocytes and leukocytes. The wbcs population consists of some leukocytes that have elevated levels of FITC autofluorescence. The left vertical line separates single platelets (<4.5 xm in diameter) from platelet aggregates, whereas the right vertical line separates small from large platelet aggregates. The latter were defined to be larger than 10 xm in equivalent sphere diameter.

Fig. 15.2 Schematic diagram of an in vitro perfusion system for laminar shear stress conditions. Flow chamber contains the biomaterial with cultivated cells (e.g. HUVECs). Perfusion with full blood, isolated leukocytes, platelets or cell culture media. Rolling pump applies various volume rates. After perfusion, the perfused cells on the biomaterial (e.g. proliferation, vitality, PCR, Western blotting) and the supernatant (e.g. flow cytometry, ELISA) should be analyzed...

Yet the observation and measurement of cell adhesion are difficult because the cells have small diameters, between 1-10 pm, and the adhesion force is generally low, typically 0.1-100 nN. Usually, cell adhesion must be studied in a microscope. Attachment of cells may then be observed in relation to the chemical environment, and the cells may be pulled apart and sensed by various techniques including direct mechanical probing, shearing with a flow, or cytometry (cell counting) to determine the adhesion quantitatively. 

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