Mechanics Seminar: Professor Jennifer Mitchel

The Mechanics Seminar Series is a weekly seminar given by campus and visiting speakers on topics across the spectrum of mechanics research (solids, fluids, and dynamics). Professor Jennifer Mitchel is a professor at Wesleyan University.

Title: Moving in a crowd: Decoding solid-fluid phase transitions of cellular collectives

Abstract: The organizational unit of life is the single cell, and yet the functional unit of multicellular organisms is the tissue, which is inherently collective. This leads to a fundamental question: how do cells self-organize into coherent, coordinated collectives? Importantly, in in vitro systems where external organizing mechanisms (e.g. tissue-level morphogen gradients) are absent, individual cells spontaneously self-organize into multicellular functional units. Towards developing an understanding of cellular self-organization into coherent collectives, we focus on the dynamics and structure of the human airway epithelium. Under homeostatic conditions, human airway epithelium is differentiated, stable, and able to withstand insults including pollution, allergens, and pathogens. This epithelial collective is typically stationary but exhibits collective migration in a range of circumstances, including during differentiation, in response to a variety of pathological stimuli, and under disease states such as asthma and COPD. As airway basal cells differentiate and form a stable tissue, they transition from a collectively migratory, fluidized state to a stationary, solid-like state. The fluidized state is characterized by cell elongation and alignment into cooperative migratory flocks, but as the collective solidifies, cells adopt more regular, isotropic, and homogenous shapes, and motion slows. This stationary, differentiated cellular collective can in turn be triggered to undergo a seemingly reverse process, in which the collective fluidizes, and large-scale, coordinated motion emerges. We find that well-described biological mechanisms can only partially account for the collective dynamics in this system, and begin to develop biophysical frameworks of cellular solidification and fluidization, towards understanding emergent multicellular coordination.

Bio: Dr. Mitchel received an undergrad degree in mechanical engineering with a minor in bioengineering from MIT, followed by graduate training in biomedical engineering with a focus on nerve tissue regeneration at Brown University. She went on to study mechanobiology and epithelial biology at the Harvard School of Public Health, and now runs a research group and teaches at Wesleyan University. Prof. Mitchel’s scientific work integrates techniques from cell and tissue engineering, mechanobiology, and cell biology, to explore how biological information at the single-cell level combines with local physical forces to drive collective cellular migration in development, regeneration, and disease. Prof. Mitchel teaches courses on cell biology, bioengineering, and cell migration. Her work has been supported by the Parker B. Francis Foundation and by the NSF.