3140 - Imaging Hematopoietic Stem Cells in Their Native Bone Marrow Microenvironment

Abstract

In recent years, considerable effort has been devoted to elucidating the molecular and cellular composition of the bone marrow niche and how it regulates hematopoietic stem cell (HSC) function. High-resolution confocal imaging of HSCs in the bone marrow is therefore an important tool for analyzing the three-dimensional (3D) architecture and spatial distribution of cells and structures in situ. However, this has been a major challenge owing to its encasement in the calcified bone and the lack of exclusive markers that allow the imaging and tracking of endogenous HSCs and niche cells. In the past few years, these limitations have been overcome by using whole-mount 3D confocal imaging of the mouse sternum or femur combined with computational analyses. These techniques allow us to evaluate the position and significant associations between rare endogenous HSCs and marrow constituents including other hematopoietic cells, and stromal structures such as blood vessels, perivascular cells and osteoblasts, which have been reported as candidate niche cells. Here, we will present and discuss the advantages and limitations of current and emerging technological advances for HSC and niche labelling, and bone marrow imaging techniques, including intravital microscopy, sternal whole-mount and clearing, that are elucidating the localization of HSCs in their native microenvironment.