Generation of a temporal, spatial, and molecular map of in situ hematopoiesis

(PLEASE KEEP IN WORD, DO NOT PDF) Enter the text here that is the new abstract information for your application. This section must be no longer than 30 lines of text. The hematopoietic system has been, arguably, the best well studied tissue from a developmental and stem cell biology perspective. Historically, the study of hematopoiesis has taken advantage of flow cytometry and cell transplantation approaches as the gold standard assays to examine functional behaviors. While these studies have provided an elegant textbook view of hematopoiesis, we argue here that our knowledge of how early blood formation works is largely incomplete. This is predominantly due to the limitations of utilizing traditional assays and readouts that disrupt the normal marrow tissue archicture and neglect the anatomical localization of cells. Thus, one key biological component missing in many studies in the field is that of spatial organization. Basic questions such as when and where hematopoietic fate commitment occurs, what the exact cellular intermediates are between a stem cell and mature daughter cells, and what the identity and role of the cellular microenvironement (niche) is in the hematopoietic process remain largely unsettled. Here, we propose an interdisciplinary approach based on state-of-the-art live microscopy manipulations in combination with novel hematopoietic fate reporters to enable a comprehensive study of hematopoiesis entirely in situ. Using novel two photon-guided collection of stem cell clones directly from the bone marrow, and longitudinal live-imaging analysis of stem cell progenies, we aim to generate a spatial, temporal and molecular map of hematopoiesis at single cell resolution. Complementary proximity-based photolabelling approaches will be taken to catalogue the cellular composition of the niche in the steady-sate, diseased, and aged settings. By moving away from tissue disruptive approaches to a system that relies on observation, manipulation, and analysis of single hematopoietic cells within the bone marrow, we hope to obtain unique insights into the cellular organization of blood production.