Mechanosensitive Stanniocalcin-1 Suppresses Smooth Muscle Cell Proliferation and Attenuates Experimental Pulmonary Hypertension

Abstract Background Idiopathic pulmonary arterial hypertension (IPAH) is driven by progressive pulmonary vascular remodeling, particularly pulmonary arterial smooth muscle cell (PASMC) proliferation. Current combination vasodilator therapies have markedly improved outcomes; however, prognosis remains poor in subgroups such as patients with respiratory comorbidities, highlighting the need for novel therapies. Elevation of intravascular hydrostatic pressure is a hallmark of IPAH, yet its direct role in PASMC pathobiology remains largely unexplored. We developed a cyclic hydrostatic pressurization culture system to model hypertensive hemodynamic stress in vitro and identify pressure-responsive mediators. Methods PASMCs from 4 patients with IPAH were exposed to high hydrostatic pressure (70/40 mmHg, 60 bpm). Transcriptomic profiling identified differentially expressed genes, validated by qPCR. Functional studies included piezo-type mechanosensitive ion channel component 1 (PIEZO1) modulation, recombinant human stanniocalcin-1 (rhSTC1) treatment, bromodeoxyuridine (BrdU) incorporation, and western blotting for cell-cycle regulators. In vivo , chronic hypoxia–induced pulmonary hypertension was assessed in wild-type and Stc1 −/− mice by hemodynamic and histological analyses, with or without intratracheal rhSTC1 administration. Results RNA sequencing revealed STC1 as a robustly pressure-induced gene in IPAH PASMCs. PIEZO1 activation upregulated STC1 , whereas knockdown blunted this response. Elevated STC1 expression was observed in PASMCs of IPAH lung tissues, and rhSTC1 reduced PASMC proliferation and increased p-p53, p21, and p27 expression. In the chronic hypoxia model, Stc1 −/− mice exhibited higher right ventricular systolic pressure (RVSP) (43.7 ± 1.3 vs. 30.6 ± 0.9 mmHg) and greater pulmonary arterial medial thickness (39.1 ± 2.5% vs. 26.5 ± 1.3%) than wild-type mice. CD68-positive macrophages were increased in Stc1 −/− mice under normoxia and further elevated with hypoxia. In wild-type and Stc1 −/− PAH models, intratracheal administration of rhSTC1 markedly reduced medial thickening, CD68-positive macrophage accumulation, and RVSP in both wild-type and Stc1 −/− mice. Conclusions We demonstrate that elevated hydrostatic pressure drives STC1 expression via PIEZO1, conferring potent anti-remodeling effects in IPAH. STC1 supplementation represents a potential therapeutic strategy that addresses an urgent medical need not fulfilled by conventional therapies. Clinical Perspective What Is New? We established a novel hydrostatic pressurization system to recapitulate idiopathic pulmonary arterial hypertension (IPAH) hemodynamic conditions in vitro . Stanniocalcin-1 ( STC1 ) is a hydrostatic pressure–responsive gene in pulmonary arterial smooth muscle cells (PASMCs) from IPAH patients, induced via the mechanosensitive receptor piezo type mechanosensitive ion channel component 1 (PIEZO1). Exogenous STC1 suppresses PASMC proliferation and attenuates pulmonary vascular remodeling in chronic hypoxia–induced PAH models. What Are the Clinical Implications? STC1 supplementation represents a potential therapeutic strategy for IPAH, acting through a non-vasodilatory mechanism. STC1 supplementation may offer benefit in patients with limited response to current vasodilator therapies or with comorbid respiratory disease. Targeting mechanotransduction pathways could expand treatment options for pulmonary hypertension.