A method for inducing equi-biaxial and uniform strains in elastomeric membranes used as cell substrates

A device is described which is designed to bring about uniform and equi-biaxial strains of 0.04-0.4% on a circular elastomeric sheet upon which cells are grown in a monolayer. Strain measurements at six different radii of the well provide evidence of the uniformity of the strain field over the 2.54 cm diameter of the well with a mean strain of 0.15% and a standard deviation of 0.01% strain. Major advantages of the system over those previously described are that (1) the substrate remains in the same plane throughout the application of stretch, (2) the device is designed to provide a state of uniform equi-biaxial strain to the entire substrate of the cells and (3) all cells 'see' the same strain field, no matter what their orientation. This allows for real-time optical monitoring of the cells throughout the stretching cycle of the cell substrate. In this way, changes in the cell membrane, cell nucleus, cytoskeleton and in fluorescently labelled calcium can be monitored microscopically during application of an equi-biaxial mechanical stretch.