Cells Under Flow
In their natural environment, endothelial cells are constantly exposed to physical and biochemical stimuli that can alter cell permeability. Laminar shear stress due to blood flow is a principal regulator of systemic endothelial cell gene expression, morphology, and the production of soluble mediators. Its importance is highlighted by pathological processes associated with reduced or absent laminar shear stress, including atherosclerosis. Endothelial transport of macromolecules has been shown to be responsive to flow shear stress, hydrostatic pressure, thermal shock, and agonists such as histamine and thrombin. The ECIS I-Flow and P-Flow solutions use combine different pump technologies with ECIS flow arrays to allow researchers to study endothelial permeability in vitro under complex shear flow conditions. Continuous or programmed pulsed pump profiles can be created. Flow arrays are available with varying channel sizes and electrode combinations. A "Y" channel flow array is also available to simulate vessel branching for arteriosclerosis research.
The I-Flow and P-Flow systems use syringe and peristaltic pumps respectively to create shear stress conditions within ECIS flow arrays. The ECIS system then monitors continuously the TEER of cell monolayers exposed the shear stress conditions. This allows for the dynamic changes in TEER to be recorded due to changes in flow rates, addition of vasoactive compounds under flow conditions, or the introduction of secondary cells. Stock ECIS flow arrays create laminar shear stress across the cells. Turbulent flow can be created by customizing the ECIS flow arrays.
Shikataa, Y., Riosa, A., Kawkitinaronga, K., DePaolab, N., Garciaa, J.G.N., Birukov, K.G., "Differential effects of shear stress and cyclic stretch on focal adhesion remodeling, site-specific FAK phosphorylation, and small GTPases in human lung endothelial cells." Experimental Cell Research Volume 304, Issue 1, 40-49 (2005).
*DePaola, N., Phelps, J.E., Florez, L., Keese, C.R., Giaever,I., Minnear, F.L., and Vincent, P. "Electrical Impedance of Cultured Endothelium Under Fluid Flow.", Annals of Biomedical Engineering 29, pp. 1-9 (2001)
Phelps, J.E., and DePaola, N. "Spatial Variation in Endothelial Barrier Function in Disturbed Flows inVitro." American Journal of Physiology: Heart and Circulatory Physiology, 278: H469-H476, (2000).
*Bovine aortic endothelial cells were grown to confluence on the ECIS array and introduced into the flow chamber. The resistive portion of the impedance (normalized to the starting value) was monitored with an ECIS system and is presented as a function of time. Flow is turned on and off as indicated by the arrows. Data was collected every minute and error bars are shown every 15 minutes.