Vitamin D improves endothelial barrier integrity and counteracts inflammatory effects on endothelial progenitor cells

Endothelial colony-forming cells (ECFCs), a proliferative subpopulation of endothelial progenitor cells, are involved in angiogenesis and endothelial repair. In this study, we investigated endothelial barrier characteristics of ECFCs, whether vitamin D supports cell-cell adhesion and barrier integrity, and how it affects ECFC mobilization and actin dynamics. Although ECFC barrier was disrupted under inflammatory conditions, this effect was rescued by vitamin D treatment, leading to higher stability of an ECFC monolayer. Furthermore, vitamin D enhanced ECFC mobilization toward directional migration. In addition, immunocytochemistry, quantitative real-time PCR, and immunoblotting analysis showed that vitamin D increased endothelial interconnections through vascular endothelial cadherin (VE-cadherin) junctions and by impacting cell dynamics through cofilin and VE-cadherin phosphorylation. Our results suggest that vitamin D treatment efficiently counteracts inflammation in an ECFC monolayer, resulting in higher ECFC barrier integrity. This study provides evidence of a new beneficial effect of vitamin D for ECFC homeostasis.-Schroder-Heurich, B., von Hardenberg, S., Brodowski, L., Kipke, B., Meyer, N., Borns, K., von Kaisenberg, C. S., Brinkmann, H., Claus, P., von Versen-Hoynck, F. Vitamin D improves endothelial barrier integrity and counteracts inflammatory effects on endothelial progenitor cells.