Suspended monolayers
Most mechanical tests on cells are done on single cells or on layers stuck to a dish, which hides how a tissue carries load. Our collaborators, Guillaume Charras (UCL) and his team, developed a way to grow a monolayer of epithelial cells between two parallel glass capillaries, free of any substrate, so that it can be stretched while it is imaged (Harris et al., PNAS 2012; Nature Protocols 2013). We contributed to the design of the set-up and to the processing of the data. When stretched, the tissue relaxes its stress within about a minute, following a power law, and this response is controlled by the actomyosin cortex of the cells (Khalilgharibi et al., Nature Physics 2019). Fractional viscoelastic models captured this behaviour with few parameters (Bonfanti et al., Royal Society Open Science 2020), and a review sets it in the wider context of cellularised materials (Khalilgharibi et al., 2016). The platform is the basis of the projects on tissue integrity and on epithelial bending.