Impact of IK Channel on CD34 Cells in Angiotensin II-Induced Arteriole Remodeling of Hypertensive Mice.

Background: Mechanisms of endothelial repair in hypertension remain unclear. CD34 cells are reported to contribute to vascular regeneration; however, their origin and regulation in hypertension are poorly understood. We investigated the role of IK channels in CD34 cell-mediated endothelial repair during Ang II (angiotensin II)-induced arteriole remodeling.

Methods: Using inducible lineage tracing (Cd34-CreERT2; R26-tdTomato), we tracked nonbone marrow-derived CD34 cells in hypertensive mice. Single-cell RNA sequencing, immunofluorescence, transwell migration assays, and patch-clamp techniques were used to analyze phenotypic transitions, ion channel activity, and signaling pathways. Bone marrow transplantation, the IK channel inhibitor TRAM-34, and the ERK (extracellular signal-regulated kinase) inhibitor PD98059 were used to validate functional mechanisms.

Results: Lineage tracing revealed that nonbone marrow-derived CD34 cells contributed to endothelial repair under hypertensive conditions. Immunofluorescence analysis showed an increase in CD31-tdTomato cells in the arterioles of Ang II-treated mice after 6 weeks, indicating improved endothelial integrity. Single-cell RNA sequencing revealed 2 subgroups of endothelial cells, one of which expressed stem cell markers such as CD34 (cluster of differentiation 34), Flk-1 (fetal liver kinase 1), and Sca-1 (stem cell antigen-1). Gene expression analysis showed that CD34 cells are involved in endothelial repair through the regulation of cell migration. Importantly, IK channel activation facilitated CD34 cell migration, and TRAM-34-based inhibition of IK channels reduced migration. Mechanistic studies revealed that Ang II enhanced CD34 cell migration via IK-mediated activation of the ERK/P38 signaling pathway, promoting cytoskeletal reorganization and increased intracellular calcium levels.

Conclusions: Arteriole-resident CD34 cells contribute to endothelial repair in Ang II-induced hypertension. Moreover, IK channel upregulation facilitates CD34 cell migration via ERK/P38 signaling, suggesting potential therapeutic targets for hypertension.