Combined single-cell and spatial transcriptomics reveal the molecular, cellular and spatial bone marrow niche organization.
Chiara Baccin, Jude Al-Sabah, Lars Velten, Patrick M Helbling, Florian Grünschläger, Pablo Hernández-Malmierca, César Nombela-Arrieta, Lars M Steinmetz, Andreas Trumpp, Simon Haas
Author Information
Chiara Baccin: Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany. ORCID
Jude Al-Sabah: Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM gGmbH), Heidelberg, Germany. ORCID
Lars Velten: Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany. lars.velten@embl.de. ORCID
Patrick M Helbling: Department of Medical Oncology and Hematology, University Hospital and University of Zürich, Zürich, Switzerland. ORCID
Florian Grünschläger: Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM gGmbH), Heidelberg, Germany. ORCID
Pablo Hernández-Malmierca: Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM gGmbH), Heidelberg, Germany. ORCID
César Nombela-Arrieta: Department of Medical Oncology and Hematology, University Hospital and University of Zürich, Zürich, Switzerland. ORCID
Lars M Steinmetz: Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany. larsms@embl.de. ORCID
Andreas Trumpp: Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM gGmbH), Heidelberg, Germany. a.trumpp@dkfz-heidelberg.de. ORCID
Simon Haas: Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM gGmbH), Heidelberg, Germany. s.haas@dkfz-heidelberg.de. ORCID
The bone marrow constitutes the primary site for life-long blood production and skeletal regeneration. However, its cellular and spatial organization remains controversial. Here, we combine single-cell and spatially resolved transcriptomics to systematically map the molecular, cellular and spatial composition of distinct bone marrow niches. This allowed us to transcriptionally profile all major bone-marrow-resident cell types, determine their localization and clarify sources of pro-haematopoietic factors. Our data demonstrate that Cxcl12-abundant-reticular (CAR) cell subsets (Adipo-CAR and Osteo-CAR) differentially localize to sinusoidal and arteriolar surfaces, act locally as 'professional cytokine-secreting cells' and thereby establish peri-vascular micro-niches. Importantly, the three-dimensional bone-marrow organization can be accurately inferred from single-cell transcriptome data using the RNA-Magnet algorithm described here. Together, our study reveals the cellular and spatial organization of bone marrow niches and offers a systematic approach to dissect the complex organization of whole organs.