Applying Mechanical Load to Cells in Monolayer Culture

Introduction
Stretching Cells with a Flexcell® Tension System
Fluid Flow with a Flexcell® Fluid Shear System
Equipment, Devices, & Consumables

 

Introduction
Cells are subjected to compression, tension, and shear in the body and undergo acute and adaptive biochemical changes in response to deformation. Stressing cells in culture simulates the in vivo environment causing dramatic morphologic and biochemical responses. There are both short and long term changes that occur when cells are loaded in culture, such as alterations in signaling, the rate and amount of protein synthesis, secretion, or degradation, the rate of cell division, changes in energy metabolism, and other changes in biochemistry and bioenergetics.

For these reasons, Flexcell® introduced tension and fluid shear systems for applying mechanical load to cells in monolayer culture. These systems have broad applications in the biomedical research field since strain, compression, or fluid flow have been found to induce biochemical changes in cells derived from a variety of tissues including cardiac, skeletal and smooth muscle, lung, vascular endothelium, skin, tendon, ligament, cartilage, and bone (see our Publication Database for a more complete list of research in these areas).
 

Stretching Cells with a Flexcell® Tension System
The FX-6000™ Tension System is a patented, computerized, pressure-operated instrument that applies a defined controlled, static or variable duration cyclic tension, to cells growing in vitro. This system utilizes regulated vacuum pressure to deform flexible-bottomed culture plates (Figure 1). When used with BioFlex® culture plates and cylindrical-shaped loading posts, this system applies an equibiaxial strain to the cells cultured in monolayer on the flexible-bottomed membrane of the BioFlex® culture well. Similarly, when used with UniFlex® culture plates and an Arctangle® loading post (Figure 2), this system applies a uniaxial strain. This system can apply a gradient biaxial strain of up to 33% in the absence of loading posts.

Equibiaxial Strain
Figure 1. Equibiaxial strain application to cells plated in a BioFlex® well.

Arctangle Loading Post
Figure 2. UniFlex® culture plate on Arctangle® Loading Stations™

The StageFlexer® allows users to visualize real-time cellular responses to tension. It is a single-well embodiment of a BioFlex® well that fits on a standard upright microscope stage. A StageFlexer® Membrane can be deformed 1) freely in the open chamber producing gradient biaxial strain or 2) across a cylindrical loading post producing equibiaxial strain.
 

Fluid Flow with a Flexcell® Fluid Shear System
Fluid-induced shear stress occurs in every tissue in the body as a result of interstitial fluid movement. Tissue deformation by compression, tension or shear forces results in the movement of interstitial fluid around cells. Fluid movement acts as a transport vehicle for ions, proteins, carbohydrates and other molecules capable of movement within the matrix. As the fluid moves past cell membranes, a shear stress, τ, is generated. If one assumes that laminar flow occurs through a parallel-plate flow chamber, fluid-induced shear stress values can be determined with the following formula: τ = 6μQ/bh2, where τ is the shear stress in dyne/cm2, μ is the viscosity of the fluid in dynes/cm2, Q is the flow rate in ml/s, b is the width of the flow channel in cm, and h is the height of the flow channel in cm.

The Streamer® is a parallel-plate flow system that is used to apply fluid-induced shear stress to cells grown in a monolayer. The system includes a six-chamber laminar flow device designed to hold 75 x 25 x 1 mm Culture Slips®. The Streamer® system can be used to apply laminar, pulsatile*, or oscillating* flow to cell in monolayer culture (Figure 3) and uses a computer-controlled peristaltic pump to regulate shear stress from 0-35 dynes/cm2.

*When used in conjunction with the Osci-Flow® Flow Controller.


Streamer Schematic
Figure 3. Fluid shear applied to cells in Streamer® device.


The FlexFlow™ is a parallel plate laminar flow device designed to apply fluid shear stress and/or cyclic strain to cells in culture while providing a means for viewing cell activity under a microscope in real time. Like the StageFlexer®, the FlexFlow™ fits on the stage of a standard upright microscope.


 

Equipment, Devices, & Consumables

 

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