U-46619

Vasoreactivity of pulmonary arteries regulates blood flow through the lungs. Excessive constriction of these vessels contributes to pulmonary arterial hypertension (PAH), a progressive and incurable condition, resulting in right heart failure. The search for new and improved drug treatments is hampered by laboratory models that do not reproduce the vasoactive behaviour of healthy and diseased human arteries.

We have developed an innovative technique for producing miniature, three‐dimensional arterial structures that allow proxy evaluation of human pulmonary artery contractility. These “engineered pulmonary artery tissues” or “EPATs” are fabricated by suspending human pulmonary artery vascular smooth muscle cells (VSMCs) in fibrin hydrogels between pairs of silicone posts, located on custom‐made racks, in 24‐well culture plates.

EPATs exhibit rapid, robust and reproducible contraction responses to vasoconstrictors (KCl, ET‐1, U46619) as well as relaxation responses to clinically approved PAH vasodilatory drugs that target several signalling pathways, such as bosentan, epoprostenol, selexipag and imatinib. EPATs composed of pulmonary artery VSMCs from PAH patients exhibit enhanced contraction to vasoconstrictors and relaxation in response to vasodilators. We also demonstrate the incorporation of endothelial cells into EPATs for the measurement of endothelium‐dependent dilatory responses.

We demonstrate the capacity and suitability of EPATs for studying the contractile behaviour of human arterial cells and preclinical drug testing. This novel biomimetic platform has the potential to dramatically improve our understanding and treatment of cardiovascular disease.

Hypertension plays a critical role in the development of vascular remodeling and atherosclerosis. STIM/Orai1 proteins mediate store‐operated Ca2+ entry (SOCE), which is one of the cellular Ca2+ signaling machinery involved in the pathological process of cardiovascular remodeling. However, the role and mechanism of Orai1/Orai1 mediated SOCE in coronary artery dysfunction caused by hypertension remain incompletely elucidated. The present study aimed to investigate the role of the Orai1/NFAT/calcineurin signaling pathway in hypertension‐induced coronary vasoconstriction impairment utilizing spontaneous hypertension rats (SHRs) and coronary arterial smooth muscle cells (CASMCs) exposed to high hydrostatic pressure (180 mmHg). Here, we found that agonists (5‐HT, U46619, and ET‐1) induced coronary artery constriction that was significantly reduced in SHRs compared with Wistar rats. The SOCE inhibitors SKF96365 and 2‐APB also significantly inhibited coronary artery constriction in both SHRs and Wistar rats; only the inhibitory effect of low concentrations (50 μM) of 2‐APB on SHRs was weaker than that of Wistar rats. Hypertension/high hydrostatic pressure (180 mmHg) induced phenotypic transformation of CASMCs, with an increase in the expression of STIM1/Orai1, Calcineurin‐NFAT2, and the synthetic phenotypic marker protein OPN, and a decrease in the contractile phenotypic marker protein SMMHC. The intervention of Orai1/Orai1 mediated SOCE (overexpression with ad‐Orai1, inhibition of SOCE channel with BTP2 or downregulation with Orai1 siRNA) regulated STIM1, Calcineurin‐NFAT2 expression, and contraction/synthesis phenotypic markers. Together, these findings suggest that hypertension leads to coronary vascular dysfunction via the upregulation of Orai1, which is required for the phenotypic transformation of VSMCs by activating the Calcineurin‐NFAT signaling pathway.