In Vivo Imaging of Single Mammalian Cells in Development and Disease

Live imaging has transformed biomedical sciences by enabling visualization and analysis of dynamic cellular processes as they occur in their native contexts. Here, we review key recent efforts applying in vivo optical imaging with single-cell resolution to mammalian systems ranging from embryos to adult tissues and organs. We highlight insights into active processes regulating cell fate and morphogenesis during embryonic development, how neuronal circuitry and non-neuronal cell types contribute to neurological functions, and how novel imaging-based approaches enable the dissection of neurological disorders and cancer with high spatio-temporal resolution. The convergence of technical advancements in accessing, visualizing, and manipulating individual cells provides an unprecedented lens to probe mammalian cellular dynamics in vivo in both physiological and pathological states. In vivo imaging enables visualization and analysis of dynamic processes in single mammalian cells as they occur within their physiological contexts. Live imaging of developing embryos has revealed dynamic cellular structures that regulate morphogenesis and allowed quantification of transcription factor dynamics as they interact with DNA to direct cell fate. Live imaging of single cells within the brain enables the coupling of cellular responses to sensory input and behavioral output. In vivo imaging has revealed critical mechanistic insights into the genesis and progression of diverse human diseases, ranging from neurological disorders to cancer. Emerging approaches such as intravital flow cytometry, light-sheet microscopy, adaptive optics, and label-free imaging techniques are transforming our ability to probe mammalian systems in vivo at the single-cell level.