Generating suspended cell monolayers for mechanobiological studies

Cell monolayers line most of the surfaces and cavities in the human body. During development and normal physiology, monolayers sustain, detect and generate mechanical stresses, yet little is known about their mechanical properties. We describe a cell culture and mechanical testing protocol for generating freely suspended cell monolayers and examining their mechanical and biological response to uniaxial stretch. Cells are cultured on temporary collagen scaffolds polymerized between two parallel glass capillaries. Once cells form a monolayer covering the collagen and the capillaries, the scaffold is removed with collagenase, leaving the monolayer suspended between the test rods. The suspended monolayers are subjected to stretching by prying the capillaries apart with a micromanipulator. The applied force can be measured for the characterization of monolayer mechanics. Monolayers can be imaged with standard optical microscopy to examine changes in cell morphology and subcellular organization concomitant with stretch. The entire preparation and testing protocol requires 3-4 d.