Integration of single-cell transcriptomes and biological function reveals distinct behavioral patterns in bone marrow...

Area of Science:

• Endothelial cell biology
• Hematopoiesis
• Tissue homeostasis

Background:

• Endothelial cell (EC) heterogeneity underlies diverse tissue functions.
• Comprehensive mapping of EC phenotypic, molecular, and functional properties remains incomplete.
• Understanding EC diversity is crucial for tissue homeostasis and disease research.

Purpose of the Study:

• To develop and validate a platform for tracing, profiling, and culturing primary ECs from different organs.
• To characterize the diversity and molecular signatures of bone marrow endothelial cells (BMECs) ex vivo.
• To investigate the role of macrophages in maintaining BMEC diversity and function in culture.

Main Methods:

• Utilized Tie2-CreERT2;Rosa26-tdTomato reporter mice for EC tracing.
• Performed single-cell mRNA sequencing on primary BMECs.
• Cultured primary BMECs ex vivo, assessing cell-cell interactions and macrophage influence.

Main Results:

• Ex vivo culture of BMECs transiently preserves molecular signatures and cell-cell interactions.
• Macrophages promote BMEC diversity, expansion, and maintain sinusoidal-like BMECs ex vivo.
• Endomucin expression identifies distinct BMEC populations with sinusoidal/arterial and tip/stalk signatures.
• Sinusoidal-like BMECs are short-lived, form 2D networks, contribute to angiogenesis, and support hematopoietic stem/progenitor cells.

Conclusions:

• The developed platform effectively preserves EC diversity and function ex vivo.
• Macrophages play a critical role in sustaining BMEC heterogeneity and function in culture.
• Distinct BMEC populations possess unique functional properties relevant to angiogenesis and hematopoiesis.
• This platform offers a valuable tool for studying ECs from various organs and exploring therapeutic strategies.