Deciphering Cellular Heterogeneity and Inheritability in Migration

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The overarching goal of our lab is to decipher cellular heterogeneity, dynamics, and inheritability using high- throughput and longitudinal single-cell analysis. Specifically, we will focus on chemotaxis toward CXCL12 as a model. Cell migration is an essential process in embryogenesis, angiogenesis, wound healing, inflammation, and cancer metastasis. Failure of cell migration can lead to defective inflammatory responses and poor repair of injured tissues. At the same time, fast migration of cancer cells is associated metastasis. Although many environmental cues, physiological processes, transcription factors, and organelle features have been discovered to regulate cell migration, we have limited understanding about why individual cells respond differently. Given the limitations of long-standing migration assays in tracking and selectively isolating individual cells, we developed a high-throughput single-cell migration platform that coordinates robotic liquid handling and autonomous image processing for rapidly quantifying motility of thousands of cells. Based on the observed cellular heterogeneity in our preliminary studies, we hypothesize that distinct mechanisms are used to enhance motility in different cells, including CXCL12 dependent signals as well as intrinsic motility drivers. We will isolate and profile fast-moving cell populations with single-cell molecular and functional analysis to test this hypothesis. We will inhibit individual and combination of multiple motility drivers to examine whether the movement of all cells can be stopped. We will further examine whether elevated cellular motility can be maintained over time and pinpoint key molecular features, focusing on copy number alterations and skewed expression of transcription factors. Compared to cellular characteristics driven by transient randomness, inheritable and stable alterations will be valuable biomarkers and therapeutic targets. Moreover, emerging evidence suggests the importance of molecular dynamics in signal transduction to determine cellular responses. Based on the preliminary data, we expect that sharp increase of the stimulus concentration rather than the duration of treatment is the key to induce cell movement. With the cutting-edge single-cell tracking capability, we will collect time-varying and quantitative information of thousands of cells, including cellular speed and persistence and fluorescent reporters of key migratory regulators. The dynamic cell data will reveal unique temporal patterns in fast- and slow- moving cells, which cannot be revealed with conventional one-time measurements. In addition to in vitro studies, we will track cell movement in the mouse ear skin with multiphoton intravital microscopy. We expect that without treatment, most cells move slowly yet a small number of cells move rapidly in vivo. Furthermore, the treatments that suppress in vitro cell movement will function in the same way in vivo. The proposed multi-dimensional cell migration studies will change how we understand cellular decision in migration and heterogeneity between cells. While we focus on chemotaxis toward CXCL12, we envision the technology and paradigm we establish will be widely applied to regulate heterogeneous cell populations in other contexts.