A human pathophysiological 3D-bone marrow model reveals immune and stromal cell heterogeneity.

The bone marrow niche is a complex microenvironment composed of stromal, endothelial, immune and hematopoietic cells. Dysregulated interactions within this niche can contribute to hematological malignancies and also occur in the context of solid cancer metastases. Here, we present a standardized three-dimensional human bone marrow (3D-BOM) model that recapitulates key features of the human niche. Indeed, we show that monocytes/macrophages from different sources acquire enhanced pro-inflammatory phenotype in 3D compared to 2D cultures. Hematopoietic progenitor cells are also influenced by this 3D niche while maintaining stemness characteristics over extended serial culture. Single-cell transcriptomics analysis highlighted human-like stromal and endothelial cells heterogeneity. In addition, we observed monocyte/macrophage and endothelial cell remodeling in the context of acute myeloid leukemia, suggesting dynamic interactions within the 3D-BOM. These findings highlight the potential of this model to investigate cellular dynamics underlying human bone marrow physiology and pathology.