Development and Exploitation of a Fully Human and Modular Organotypic Bone Marrow Niche Model to Study the Role of Stroma-Produced Factors in Human MDS

• Published in: Blood 2020-11, Vol.136 (Supplement 1), p.23-23
• Main Authors: Schaeffer, Alexander, Czlonka, Ewelina, Tirado-González, Irene, Böse, Thomas, Beauvarlet, Jennifer, Kur, Ivan, Bözec, Aline, Bönig, Halvard, Brandts, Christian H., Platzbecker, Uwe, Götze, Katharina S., Medyouf, Hind
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2020-142782

Background: Myelodysplastic syndromes (MDS) are a heterogenous group of stem cell driven disorders primarily affecting the elderly and characterized by inefficient production of mature blood cells and a high risk (30%) of evolution to secondary acute myeloid leukemia. Despite tremendous progress in the past decade, treatment options for MDS patients remain limited, and primarily address disease symptoms, rather than altering disease course. This points to the urgent need to better understand the pathogenesis of this heterogenous group of syndromes to develop new therapies that address disease vulnerabilities. However, this effort has been largely hampered by the limited availability of model systems that allow the exploration of MDS biology in a fully humanized setting. In recent years, studies from our lab and others, have highlighted the crucial role niche cells play in human MDS, hence reinforcing the notion that MDS is a disease of a tissue rather than hematopoietic cells alone. Therefore, exploration of MDS biology requires the further development of fully human MDS models in which both constituents of the disease, namely hematopoietic and niche cells, are present. Methods: To address this issue we successfully isolated endothelial cells (ECs) and mesenchymal stromal cells (MSC) from bone marrow biopsies obtained from MDS patients or healthy age matched controls, and subsequently utilized them to develop fully human 2D and 3D organotypic niche models, which were successfully used to support normal and MDS HSPCs expansion ex-vivo. The 3D system makes use of a collagen scaffold, as this protein makes up for 90% of the matrix proteins in the bone. Importantly, MSC and EC cultures could be successfully established from several independent donors and immortalized to generate primary cell lines that can be used to reproducibly establish these ex-vivo systems in a robust manner. Moreover, we could show that these niche cells were easily amenable to genetic editing using CRISPR-Cas9 technology as well as modified to carry fluorescent reporter proteins for tracking cellular interactions using live cell imaging and confocal microscopy. Results: In this work, we successfully isolated human mesenchymal and endothelial cells, from primary bone marrow biopsies (MDS and healthy) and established fully human 2D and 3D organotypic co-cultures ex-vivo. Of note, although bone marrow ECs represent an essential component of the hematopoietic niche, they have so far been om