“Sea”-ing Is Believing: In Vivo Imaging of Hematopoietic Stem Cells and Cancer Using Zebrafish

Purpose of Review: Communication between cells and their environment regulates their behaviors. Like a naturalist who watches animals to understand them, visualizing cells within their native ecosystems provides clues into how they work. In this review, we discuss recent findings using in vivo imaging in zebrafish to understand the behaviors of hematopoietic stem and progenitor cells (HSPCs) and cancer. Recent Findings: Recent studies visualizing the birth and migration of HSPCs throughout development and adulthood have revealed the contributions of signals from somites, immune cells, and stromal cells in modulating HSPC fate decisions. New studies in zebrafish cancer have also revealed the earliest initiation of tumorigenesis, the complex interplay of heterogenous tumor cells with each other and their environment, and how these interactions influence tumor migration and metastasis. Summary: These insights aid our understanding of cell-cell communications that are critical for making advances in regenerative medicine and cancer therapeutics.