Project Summary Cell-cell signaling maintains homeostatic functions in the presence of a dynamic environment that involves cell- derived paracrine factors, mechanical cues, and varying oxygen levels. Macrophages and fibroblasts are key cell types present in almost all mammalian tissues that integrate diverse signals from their environment and are involved in tissue homeostasis. Existing experimental models have not been able to precisely control cell-derived factors and oxygen levels while simultaneously monitoring cell migration and cell-cell communication at the single cell level in the extracellular matrix (ECM). Hence, a critical knowledge gap exists in understanding the fundamental mechanisms that control intercellular signaling in complex microenvironments. My research group will address this knowledge gap by investigating two key questions: (1) How is macrophage migration regulated by the interplay between fibroblast-secreted paracrine and mechanical cues in a 3D environment? (2) How do low oxygen levels modulate fibroblast activation, ECM remodeling, and macrophage-fibroblast crosstalk? To address the first question, we will integrate intracellular signaling biosensors with a novel microfluidic technology to control paracrine factors and cell-generated forces precisely. Results from these studies will uncover fundamental principles of cell migration. To address the second question, we will engineer multi-layer microfluidic devices with integrated imaging-based multiplexed analysis of fibroblast activation and measurement of mechanical forces. Results from the second question will provide mechanistic insights into the physiological process of multicellular oxygen-sensing and ECM remodeling. Our past studies and preliminary results using 3D microfluidic devices demonstrate the feasibility of engineering tissue microenvironments and controlling cellular responses in real-time. In summary, the proposed studies will establish a new microfluidics-based approach to studying basic mechanisms of cell migration and ECM remodeling in tissue microenvironments with spatiotemporally defined oxygen landscapes, mechanical forces, and paracrine factors.

Project Narrative Cell-cell communication plays a critical role in organ development and healing responses following injury and disease progression. Here, we employ an integrative approach of bioengineering tools, intracellular signaling reporters, and computational modeling to (1) study mechanisms that orchestrate paracrine- and mechanically induced migratory decisions in macrophages and (2) elucidate oxygen-dependent fibroblast activation and ECM remodeling via interactions with macrophages. These studies will contribute to our understanding of homeostatic macrophage-fibroblast crosstalk and lay the foundation for future studies on dysfunctional macrophage-fibroblast interactions.