Impact of IKCa Channels on CD34+ Cells in Arteriole Remodeling in Angiotensin II-Induced Hypertension Model Mice.

Abstract

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 IKCa 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 IKCa 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, IKCa channel activation facilitated CD34+ cell migration, and TRAM-34-based inhibition of IKCa channels reduced migration. Mechanistic studies revealed that Ang II enhanced CD34+ cell migration via IKCa-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, IKCa channel upregulation facilitates CD34+ cell migration via ERK/P38 signaling, suggesting potential therapeutic targets for hypertension.