3051 – SEQUENTIAL SPECIFICATION OF EMBRYO-LIKE HEMATOPOIETIC WAVES IN A HEMOGENIC GASTRULOID MODEL ABLE TO ENGRAFT HEMATOPOIETIC TISSUES

• Published in: Experimental hematology 2024-08, Vol.137, p.104373, Article 104373
• Main Authors: Cicirò, Ylenia, Ragusa, Denise, Suen, Chun-Wai, Cortès, Gabriel Torregrosa, Pastorino, Fabio, Johns, Ayona, van den Brink, Susanne, Cerveira, Joana, Kranc, Kamil, Hernandez-Hernandez, Victor, Ponzoni, Mirco, Bigas, Anna, Garcia-Ojalvo, Jordi, Arias, Alfonso Martinez, Pina, Cristina
• Format: Article
• Language: English
• ISSN: 0301-472X
• DOI: 10.1016/j.exphem.2024.104373

Hematopoietic development in the embryo is a complex process of sequential specification of different progenitors in different topographies, and late emergence of hematopoietic stem cells (HSC) in the aorta-gonad-mesonephros (AGM). Dissection of mechanisms governing progenitor and HSC specification is key to (1) robust lab production of HSC and blood cells for clinical use, and (2) therapeutic targeting of developmental leukemias. Despite proof-of-principle successes in HSC generation from pluripotent stem cells (PSC), a robust in vitro model of hemogenic development that recapitulates successive hematopoietic niches is still lacking. Recently, self-organising 3D PSC aggregates named gastruloids were shown to recapitulate key developmental processes of gastrulation, somitogenesis and early organogenesis with temporal and spatial accuracy. We sought to explore their potential in reconstructing hematopoiesis. Herein, we describe a hemogenic gastruloid (hGx) initiated from mouse embryonic SC. Through sequential use of a minimum set of growth factors that modulate key hemogenic events, we captured time-dependent specification of: (1) lateral plate mesoderm; (2) venous and arterial endothelium, (3) two waves of HE formation with associated production of (4) first, yolk sac-like erythroid-myeloid progenitors and later, AGM-like myelo-lymphoid progenitors and multipotent progenitors/pre-HSC. AGM-like hematopoiesis was accompanied by generation of mesenchymal cells and incipient specification of autonomic neurons required for HSC development. Through hGx implantation in a mature adrenal niche, we obtained hematopoietic engraftment of the bone marrow and spleen of immunodeficient mice at 4 weeks and are currently analysing long-term potential. Altogether, hGx show promise as self-organising models of hematopoiesis easily accessible for clinical scaling and mechanistic studies.