Cellular cruise control: energy expenditure as a regulator of collective migration in epithelia

Epithelial migration is implicit in processes ranging from gastrula development to the healing of skin, and involves the coordinated motion, force production, and resulting energy expenditure of thousands of constitutive cells. However, the spatiotemporal patterning and regulation of energy expenditure during epithelial migration remains poorly understood. Here, we propose a continuum mechan-ics framework and use it to explore how energy expenditure regulates epithelial migration. We use canonical mechanical metrics such as force, work and power to define what it means for a tissue to migrate efficiently and show that freely expanding epithelia actively regulate themselves to operate within a maximally efficient regime. We then leverage electrotaxis (directed motion in response to an externally applied electric field) as a tool to study non-homeostatic migra-tion using this new framework. We show that regulation of migration is robust to external cues and acts to to attenuate a tissues response to stimuli.