Stress-Induced Changes in Bone Marrow Stromal Cell Populations Revealed through Single-Cell Protein Expression Mapping

Abstract

Stromal cell populations that maintain hematopoietic stem and progenitor cells (HSPCs) are generally characterized in steady-state conditions. Here, we report a comprehensive atlas of bone marrow stromal cell subpopulations under homeostatic and stress conditions using mass cytometry (CyTOF)-based single-cell protein analysis. We identified 28 subsets of non-hematopoietic cells during homeostasis, 14 of which expressed hematopoietic regulatory factors. Irradiation-based conditioning for HSPC transplantation led to the loss of most of these populations, including the LeptinR⁺ and Nestin⁺ subsets. In contrast, a subset expressing Ecto-5'-nucleotidase (CD73) was retained and a specific CD73⁺NGFR^high population expresses high levels of cytokines during homeostasis and stress. Genetic ablation of CD73 compromised HSPC transplantation in an acute setting without long-term changes in bone marrow HSPCs. Thus, this protein-based expression mapping reveals distinct sets of stromal cells in the bone marrow and how they change in clinically relevant stress settings to contribute to early stages of hematopoietic regeneration.

Keywords: acute blood regeneration; bone marrow stromal cells; bone marrow transplantation; ecto-5′-nucleotidase; hematopoietic stress; mass cytometry; stem cell niche; stromal heterogeneity.