Lineage tracing meets single-cell omics: opportunities and challenges

A fundamental goal of developmental and stem cell biology is to map the developmental history (ontogeny) of differentiated cell types. Recent advances in high-throughput single-cell sequencing technologies have enabled the construction of comprehensive transcriptional atlases of adult tissues and of developing embryos from measurements of up to millions of individual cells. Parallel advances in sequencing-based lineage-tracing methods now facilitate the mapping of clonal relationships onto these landscapes and enable detailed comparisons between molecular and mitotic histories. Here we review recent progress and challenges, as well as the opportunities that emerge when these two complementary representations of cellular history are synthesized into integrated models of cell differentiation. Understanding developmental trajectories has recently been enabled by progress in modern lineage-tracing methods that combine genetic lineage analysis with omics-based characterization of cell states (particularly transcriptomes). In this Review, Wagner and Klein discuss the conceptual underpinnings, experimental strategies and analytical considerations of these approaches, as well as the biological insights gained.