Seminar - Professor Yimin Luo
Ordered Materials Meet Living Cells: Engineering Alignment and Programmable Force Actuation
Professor Yimin Luo is an assistant professor in the Department of Mechanical Engineering and Materials Science at Yale University.
Conte A110/A111. Refreshments @ 3:00pm. Talk begins @ 3:35pm.
Hosted by Maria Santore
Bio: Yimin Luo has been an assistant professor in the Department of Mechanical Engineering at Yale University since Jan 2023, with a joint appointment in Chemical and Environmental Engineering. Her research aims to combine high-throughput experiment design with simulation codes and machine learning algorithms to extract system dynamics, and to study out-of-equilibrium phenomena, ranging from biophysics, phase behaviors, rheology of suspensions, to active nematics. She holds a bachelor’s degree from Rice University and a Ph.D. from the University of Pennsylvania. Prior to her current position, she was a postdoctoral scholar at the University of Delaware and an Otis William Fellow at the University of California, Santa Barbara. Yimin has received various recognitions including the NSF CAREER, the Langmuir Student Oral Presentation Award, MIT ChemE Rising Stars, and University of Washington Distinguished Young Scholars Seminar Series.
Abstract: Highly regulated cellular anisotropy is widely observed in vivo. Yet, capturing tissue anisotropy in vitro is an open challenge, as collective behaviors of cells are typically studied in isotropic settings. While considerable literature exists on engineering cell alignment, limited efforts have been directed toward emulating and predicting morphogenic pathways influenced by anisotropic cell proliferation, force generation, and modifications in the surrounding matrices, in a tightly coupled process. In 2D, we show that flat substrates with orientational order can induce global alignment on a millimeter scale. Remarkably, single cells are not sensitive to the substrate’s anisotropy. Rather, the emergence of global nematic order is a collective phenomenon that requires both steric effects and molecular-scale anisotropy of the substrate. Owing to steric interactions, these elongated cells exhibit local order; topological defects, where alignment is disrupted, have been postulated to serve as mechanical centers. We find that incorporating a slower-moving phenotype slows defect recombination. In 3D, we demonstrate the fabrication of initially flat, thin, free-standing, cell-laden matrix sheets with controllable shape-morphing capabilities. First, we fabricate hydrogels with fibrin-like morphologies. Next, we embed human dermal fibroblasts in collagen and grow them on pre-ordered hydrogels. Cells align following the anisotropic cues and remodel the collagen. These cell-laden collagen sheets spontaneously contract through the traction force of the encapsulated cells. By programming the orientation of the cells, we can control the macroscopic shape transformation of the matrix. These oriented cell sheets are modular, requiring minimal instrumentation and no special release mechanism, aiding their wide adaptation. Our work establishes the groundwork for generating matrices that can undergo orientationally directed shape transformations, paving the way for the ultimate realization of in vitro morphogenesis.