Stem cell factor is selectively secreted by arterial endothelial cells in bone marrow

Area of Science:

• Hematology
• Stem Cell Biology
• Vascular Biology

Background:

• Endothelial cells (ECs) in bone marrow support hematopoietic stem cell (HSC) maintenance.
• The specific roles of different EC subtypes, like arterial endothelial cells (AECs) and sinusoidal endothelial cells (SECs), are not well understood due to isolation challenges.

Purpose of the Study:

• To differentiate and isolate AECs from SECs.
• To investigate the distinct contributions of AECs and SECs to HSC maintenance and recovery.

Main Methods:

• Developed a method using podoplanin (PDPN) and Sca-1 expression to distinguish AECs (Sca-1^bright PDPN^-) from SECs (Sca-1^dim PDPN^+).
• Utilized genetic deletion of stem cell factor (Scf) in AECs and SECs.
• Performed lineage-tracing analyses after genotoxic insults.

Main Results:

• AECs, but not SECs, were found to secrete most EC-derived stem cell factor (SCF).
• Genetic deletion of Scf in AECs significantly reduced functional HSCs.
• AEC-derived SCF promotes HSC recovery post-myeloablation.
• AECs and SECs demonstrate independent self-regeneration after genotoxic stress.

Conclusions:

• Heterogeneity exists within bone marrow ECs regarding their function in HSC niches.
• AECs play a critical role in HSC maintenance and recovery through SCF secretion.
• Distinct EC subtypes possess unique regenerative capacities.