HO-1-modified umbilical cord MSCs alleviate pulmonary arterial hypertension by reducing inflammation and endothelial dysfunction.

Abstract

Objective: To evaluate the efficacy of MSCs-HO-1 in pulmonary arterial hypertension (PAH) and explore the underlying mechanisms.

Methods: HO-1 expression and localization in lung tissues and vessels were assessed using spatial transcriptomics and single-cell RNA sequencing analyses of human PAH. MSCs-HO-1 were intravenously administered in rat and mouse PAH models (MCT-induced and SuHx). Hemodynamics (RVSP), right ventricular hypertrophy index (RVHI), survival rate, and vascular remodeling were assessed by HE staining and α-SMA immunostaining. Inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-18, IL-10, TGF-β, IL-4, IL-1Ra), ROS levels, and endothelial molecules [nitric oxide (NO) and prostaglandin I2 (PGI2)] were measured. RNA sequencing (RNA-seq) of PAECs was followed by pathway analysis and MAPK validation.

Results: HO-1 was downregulated in PAH patients and models, mainly in the vascular endothelium. MSCs-HO-1 significantly reduced RVSP, RVHI, vascular remodeling, and improved survival compared to unmodified MSCs and HO-1 alone. MSCs-HO-1 inhibited pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-18), increased anti-inflammatory factors (IL-10, TGF-β, IL-4, IL-1Ra), reduced ROS, and restored NO/PGI2. PAEC migration and proliferation abnormalities were corrected. RNA-seq revealed multiple synergistic pathways, with MAPK playing a key role in endothelial protection.

Conclusion: MSCs-HO-1 enhances endothelial function and pulmonary vascular remodeling by modulating antioxidant and immune responses, restoring NO-PGI2 signaling, and suppressing MAPK-mediated inflammation, providing more stable and significant effects than MSCs or HO-1 alone.