ABSTRACT
Hematopoietic stem cells and more committed progenitors (collectively referred to as HSPCs) emerge from vessels during development, via endothelial-to-hematopoietic transition (EHT). Recently, using the zebrafish embryo, we showed that two EHT cell types emerge from the dorsal aorta, raising the question of their subsequent fate. To address this issue, we established a complex pipeline based on single-cell photoconversion and transgenic lines to characterize the abilities of EHT cell progenies to conquer hematopoietic organs and to obtain their transcriptomic profiles. We show that the two EHT cell types lead to partly differentially fated cells, with significant differences in thymus colonization and T-lymphoid lineage commitment. In addition, we investigated implantation of HSPCs in niches, with the support of HSPC signatures (gata2b and cd34/podocalyxin), retrieved from our single-cell datasets. This revealed, at unprecedented resolution, the homing of HSPCs in niches of entire early larvae, including the pronephros, the sub-aortic and caudal regions, as well as the area contacting the supra-intestinal artery. Our work provides new insights into fundamental aspects of HSPC fate acquisition, from their emergence to their homing in specific niches.
Footnotes
Author contributions
Conceptualization: L.T., A.A.S.; Data curation: L.T., A.A.S.; Formal analysis: L.T., Y.L.-M., A.A.S.; Funding acquisition: A.A.S.; Investigation: L.T., C.V., S.S., Y.L.-M., A.A.S.; Methodology: L.T., C.V., S.S., Y.L.-M., A.A.S.; Project administration: A.A.S.; Resources: L.T., S.S., A.A.S.; Software: L.T., Y.L.-M.; Supervision: A.A.S.; Validation: L.T., S.S., A.A.S.; Visualization: L.T., A.A.S.; Writing – original draft: L.T., A.A.S.; Writing – review & editing: L.T., A.A.S.
Funding
This work was supported by Institut Pasteur, Centre National de la Recherche Scientifique (CNRS), grants from Ligue Contre le Cancer Comité de Paris (RS21/75-5 and RS22/75-9 to A.A.S.), a grant from the CNRS ‘Stem cells in vivo’ (GDR3740 to L.T.). L.T. was recipient of a PhD fellowship from the Collège Doctoral, Sorbonne Université, and from LabEx Revive consortium (ANR-10-LABX-73).
Data and resource availability
Datasets for this work have been deposited in the open external repository Zenodo (https://zenodo.org/): source data for Fig. 2, https://doi.org/10.5281/zenodo.13886928; source data for Figs 3-5 and Figs S2-S8, https://doi.org/10.5281/zenodo.13904330; source data for Fig. 6, https://doi.org/10.5281/zenodo.13884530, https://doi.org/10.5281/zenodo.13884643, https://doi.org/10.5281/zenodo.13884760, https://doi.org/10.5281/zenodo.13884837 and https://doi.org/10.5281/zenodo.13884901; source data for Fig. 7, https://doi.org/10.5281/zenodo.13885925. The Source Data Table has been deposited in Zenodo at https://doi.org/10.5281/zenodo.15691107. The scRNA-sequencing datasets generated during this study have been deposited in GEO under the accession numbers GSE299770 (Chromium analysis) and GSE300039 (Mars-seq analysis).
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