Imaging tissue remodeling during Endothelial to Hematopoietic Transition (EHT) in the zebrafish embryo

International audience; Using the Danio Rerio embryo as a model, we demonstrated that hematopoietic stem cells (HSCs) emerge directly from the aorta floor through a process we named the endothelial haematopoietic transition (EHT). However, the molecular and cellular events driving this process still have to be addressed. In particular, we aim to characterize how tissue remodelling occurring during in EHT is linked to the underlying genetic reorganization. This interdisciplinary project capitalizes on the specific assets of the zebrafish model together with our expertise in 4D microscopy, 3D-image rendering and biophysical modeling. We focus on deciphering the sequence of events that govern EHT. Analysis of high resolution 4D confocal microscopy in collaboration with a team of biophysicists provides us with physico-mathematical models. This modelling integrates the role of the different mechanical forces applied to the vessel (shear stress, stretching, bending) as well as the cytoskeleton dynamics. The coordination of these key players allows the emergence of HSC without compromising the vessel integrity. Using new microscopy techniques, we also characterize the cellular environment of the AGM and assess the role of each cell component in the initiation and mobilization of the HSCs.This project will shed light on a critical biological process and may have direct applications in tissue engineering and regenerative therapies.