An Easy-to-Fabricate Cell Stretching System Reveals Density-Dependent Mechanical Regulation of Collective Cell Movements in Epithelial Homeostasis

AO_SCPLOWBSTRACTC_SCPLOWMechanical forces regulate many facets of tissue biology. Studying the effects of forces on cells requires real-time observations of single- and multi-cell dynamics in tissue models during controlled external mechanical input. Many of the existing devices used to conduct these studies are costly and complicated to fabricate, which reduces the availability of these devices to many laboratories. In this report, we show how to fabricate a simple, low-cost uniaxial stretching device with readily available materials and instruments that is compatible with high-resolution time-lapse microscopy of adherent cell monolayers. In addition, we show how to construct a pressure controller that induces a repeatable degree of stretch in monolayers, and a custom MATLAB code to quantify individual cell strains. Finally, as an application note using this device, we show that uniaxial stretch slows down cellular movements in an epithelial monolayer in a cell density-dependent manner that involves the relocalization of myosin downstream of Rho-associated protein kinase (ROCK). This mechanical device provides a platform for broader involvement of engineers and biologists in this important area of tissue biology.