Figure 1 from Human Bone Marrow Organoids for Disease Modeling, Discovery, and Validation of Therapeutic Targets in Hematologic Malignancies
Khan AO., Rodriguez-Romera A., Reyat JS., Olijnik A-A., Colombo M., Wang G., Wen WX., Sousos N., Murphy LC., Grygielska B., Perrella G., Mahony CB., Ling RE., Elliott NE., Karali CS., Stone AP., Kemble S., Cutler EA., Fielding AK., Croft AP., Bassett D., Poologasundarampillai G., Roy A., Gooding S., Rayes J., Machlus KR., Psaila B.
<p>Mixed-matrix hydrogels containing Matrigel and type I and IV collagens are optimal for production of vascularized, myelopoietic organoids. <b>A,</b> (i) Central bone marrow is a complex tissue including MSC, endothelial, hematopoietic stem and progenitor cell (HSC/HSPCs), and myeloid and lymphoid subsets. (ii) Hematoxylin and eosin–stained section and (iii) model of human bone marrow highlighting the diverse hematopoietic and stromal cell types (created using <a href="https://BioRender.com" target="_blank">BioRender.com</a>). <b>B,</b> Differentiation workflow, in which iPSC aggregates undergo mesodermal induction (days 0–3) and commitment to hematopoietic and vascular lineages (days 3–5). Cell aggregates are then embedded in mixed-matrix hydrogels comprised of Matrigel and collagen I, collagen IV, or collagen I + IV mix at a 40:60 ratio to support vascular sprouting. Key media components are listed for each phase. Gating strategy (<b>C</b>) and quantification (<b>D</b>) of stromal and hematopoietic cell types in day 18 organoids supported by Matrigel + collagen type I–only, collagen IV–only, and collagen I + IV hydrogels. MK, megakaryocyte. <b>E,</b> Distribution of lineages as fractions of the whole organoid population. <b>F,</b> Radius of endothelial sprouts. <b>G,</b> Sprouting day 12 organoids immunostained for nuclei (DAPI), CD34, and CD144 (VE-cadherin). <b>H–J,</b> Whole organoid Z-stack imaging acquired at day 18 showing CD34<sup>+</sup> HSPCs and UEA1<sup>+</sup> vessels that are negative for CD34 (<b>H</b>), CD41<sup>+</sup> megakaryocytes (<b>I</b>), and CD71<sup>+</sup> erythroid cells dispersed throughout the organoids and associating with CD144<sup>+</sup>/UEA1<sup>+</sup> vasculature (<b>J</b>). *, <i>P</i> < 0.05; ***, <i>P</i> < 0.001 for one-way ANOVA with multiple comparisons [Fisher least significant difference (LSD)]; <i>n</i> = 3 for endothelial sprout radius measurements. Two-way ANOVA with multiple comparisons (Fisher LSD); <i>n</i> = 3 (3 independent differentiations, 15 pooled organoids each) for flow cytometry analysis. Representative images are shown. See also Supplementary Fig. S1.</p>