ABCG2-Expressing Clonal Repopulating Endothelial Cells Serve to Form and Maintain Blood Vessels

Area of Science:

• Vascular Biology
• Stem Cell Biology
• Regenerative Medicine

Background:

• Most organs rely on resident stem/progenitor cells for lifelong maintenance.
• The regenerative potential of mature endothelial cells (ECs) is limited, and the existence of vascular stem/progenitor cells remains unclear.
• A specific marker for vascular clonal repopulating ECs (CRECs) has been lacking, hindering the study of their self-renewal and vessel-forming mechanisms.

Purpose of the Study:

• To identify and characterize vascular stem/progenitor cells with EC-repopulating potential.
• To determine if ABCG2-expressing ECs function as CRECs in human and mouse vasculature.
• To elucidate the molecular mechanisms underlying the regenerative potential of these cells.

Main Methods:

• Analysis of colony-forming, self-renewal, and vessel-forming potential of ABCG2-expressing ECs from human umbilical vessels.
• Development of Abcg2Cre^Ert2;ROSA TdTomato mice for lineage tracing during development and after myocardial infarction injury.
• RNA sequencing and ChIP-sequencing to investigate gene regulation in Abcg2-expressing ECs.

Main Results:

• Endothelial cells with higher ABCG2 expression (ABCECs) exhibit enhanced clonal proliferative and in vivo vessel-forming potential in both human and mouse vessels.
• Transplantation studies confirmed the ability of ABCECs to contribute clonally to vessel formation in recipients.
• Lineage tracing demonstrated that Abcg2-expressing CRECs (AbcCRECs) contribute to arterial, venous, and capillary development and regeneration in cardiac tissue post-myocardial infarction.
• Transcriptome and epigenetic analyses revealed an enrichment of angiogenesis and vessel development gene signatures in AbcCRECs, with specific angiogenic genes like Notch2 and Hey2 showing bivalent histone modifications.

Conclusions:

• This study identifies a prospective marker (ABCG2 expression) for vascular CRECs in both mice and humans.
• These findings establish the functional identity of ABCECs as CRECs with significant regenerative capacity.
• The identification of CRECs and their regulatory mechanisms holds promise for developing novel cell therapies for vascular repair in conditions like endothelial dysfunction.