Superstretching epithelial sheets

During morphogenesis, cell monolayers need to change their shape in various ways. For instance, cell monolayers undergo very large stretching during blastocyst hatching in mammalian embryos. In this talk, I will discuss a mechanism by which epithelial tissues can withstand extreme stretches without significantly increasing tissue tension, which would otherwise compromise tissue integrity [1]. I will describe how, under applied tension, epithelial cells can adopt two "metastable" states, one in a barely stretched state, and one in a superstretched state. This phase coexistence allows tissues to further stretch at constant tension by switching cells into the super-stretched phase, in close analogy with the phenomenology of superelasticity exhibited by NiTi alloys or by intermediate filaments. In epithelial monolayers, this phenomenology has an active origin that depends on cytoskeletal dynamics. I will present experimental evidence of epithelial active superelasticity, a theoretical model explaining it and bridging from cytoskeletal dynamics to emergent material behavior, and will discuss the implications during morphogenesis.

[1] Active superelasticity in three-dimensional epithelia of controlled shape, E. Latorre et al, Nature (in press),
https://doi.org/10.1038/s41586-018-0671-4