A KLF2-BMPER-Smad1/5 checkpoint regulates high fluid shear stress-mediated artery remodeling

Fluid Shear Stress-Regulated Vascular Remodeling: Past, Present, and Future

The vascular system remodels throughout life to ensure adequate perfusion of tissues as they grow, regress, or change metabolic activity. Angiogenesis, the sprouting of new blood vessels to expand the capillary network, versus regression, in which endothelial cells die or migrate away to remove unneeded capillaries, controls capillary density. In addition, upstream arteries adjust their diameters to optimize blood flow to downstream vascular beds, which is controlled primarily by vascular endothelial cells sensing fluid shear stress (FSS) from blood flow. Changes in capillary density and small artery tone lead to changes in the resistance of the vascular bed, which leads to changes in flow through the arteries that feed these small vessels. The resultant decreases or increases in FSS through these vessels then stimulate their inward or outward remodeling, respectively. This review summarizes our knowledge of endothelial FSS-dependent vascular remodeling, offering insights into potential therapeutic interventions. We first provide a historical overview, then discuss the concept of set point and mechanisms of low-FSS-mediated and high-FSS-mediated inward and outward remodeling. We then cover in vivo animal models, molecular mechanisms, and clinical implications. Understanding the mechanisms underlying physiological endothelial FSS-mediated vascular remodeling and their failure due to mutations or chronic inflammatory and metabolic stresses may lead to new therapeutic strategies to prevent or treat vascular diseases.

Artery regeneration: Molecules, mechanisms and impact on organ function

Replenishment of artery cells to repair or create new arteries is a promising strategy to re-vascularize ischemic tissue. However, limited understanding of cellular and molecular programs associated with artery (re-)growth impedes our efforts towards designing optimal therapeutic approaches. In this review, we summarize different cellular mechanisms that drive injury-induced artery regeneration in distinct organs and organisms. Artery formation during embryogenesis includes migration, self-amplification, and changes in cell fates. These processes are coordinated by multiple signaling pathways, like Vegf, Wnt, Notch, Cxcr4; many of which, also involved in injury-induced vascular responses. We also highlight how physiological and environmental factors determine the extent of arterial re-vascularization. Finally, we discuss different in vitro cellular reprogramming and tissue engineering approaches to promote artery regeneration, in vivo. This review provides the current understanding of endothelial cell fate reprogramming and explores avenues for regenerating arteries to restore organ function through efficient revascularization.

cSTAR analysis identifies endothelial cell cycle as a key regulator of flow-dependent artery remodeling

Fluid shear stress (FSS) from blood flow sensed by vascular endothelial cells (ECs) determines vessel behavior, but regulatory mechanisms are only partially understood. We used cell state transition assessment and regulation (cSTAR), a powerful computational method, to elucidate EC transcriptomic states under low shear stress (LSS), physiological shear stress (PSS), high shear stress (HSS), and oscillatory shear stress (OSS) that induce vessel inward remodeling, stabilization, outward remodeling, or disease susceptibility, respectively. Combined with a publicly available database on EC transcriptomic responses to drug treatments, this approach inferred a regulatory network controlling EC states and made several notable predictions. Particularly, inhibiting cell cycle-dependent kinase (CDK) 2 was predicted to initiate inward remodeling and promote atherogenesis. In vitro, PSS activated CDK2 and induced late G1 cell cycle arrest. In mice, EC deletion of CDK2 triggered inward artery remodeling, pulmonary and systemic hypertension, and accelerated atherosclerosis. These results validate use of cSTAR and identify key determinants of normal and pathological artery remodeling.