Fangyu Liu

Zhongshan Hospital Fudan University, China

Single-Cell Sequencing Reveals Hypoxia-Driven Vascular Remodeling in Hypertrophic Cardiomyopathy

Biography

Liu pursued his studies in Cardiac Surgery at Zhongshan Hospital, Fudan University, in Shanghai, China. He earned his Ph.D. in 2025 and subsequently entered the cardiac surgery residency program at the same institution. To date, he has published over ten research articles in peer-reviewed SCI(E) journals.

Abstract

Background: Hypertrophic cardiomyopathy (HCM) features myocardial hypertrophy and microvascular dysfunction, but hypoxia-driven vascular adaptation mechanisms remain undefined. This study deciphers endothelial cell (EC) and vascular smooth muscle cell (VSMC) heterogeneity in HCM using single-cell transcriptomics.

Methods: 121,176 single-cell transcriptomes from 17 human samples (11 HCM, 6 controls; sourced from 7 public repositories) were analyzed. After quality control (mitochondrial genes <20%, gene counts 200-7,500), batch correction (Seurat V4.1 reciprocal PCA), and clustering (Louvain, resolution=0.8), ECs (CDH5/PECAM1+) and VSMCs (RGS5/PDGFRB+) were subclustered. Intercellular communication (CellChat), pseudotime trajectories (Monocle2/DDRTree), and pathway enrichment (clusterProfiler, FDR<0.05, |log2FC|>1) were assessed.

Results: HCM myocardium exhibited expanded hypoxia-responsive ECs (32.1% vs. 12.4% controls) with upregulated HIF1A (log2FC=2.8), EPAS1 (log2FC=2.3), and glycolytic genes (HK2 log2FC=3.1), but downregulated angiogenesis effectors (VEGFR2 log2FC=?1.7). VSMCs showed phenotypic polarization: stressed/proliferative subtypes increased to 28.7% (vs. 8.9% controls) with inflammatory (IL6 log2FC=7.1) and cell cycle activation (MKI67 log2FC=9.3), while contractile VSMCs decreased (41.2% vs. 68.5%). Pseudotime analysis revealed 86% of stressed VSMCs in terminal states with persistent HIF1A activation and embryonic factor IRX2 overexpression (log2FC=13.2).

EC-myocyte interactions via FN1-integrin signaling increased 1.8-fold (p=2.5×10??), while macrophage-VSMC crosstalk via SPP1-CD44 rose 1.9-fold (p=1.4×10?³), correlating with fibrosis. Spatial analysis showed endocardial ECs maintained NOTCH3-mediated barrier function (NOTCH3 log2FC=7.9).

Conclusions: Chronic hypoxia drives HCM vascular ecosystem dysregulation: ECs adopt metabolically hyperactive/angiogenically inert phenotypes, while VSMCs undergo embryonic reversion via IRX2. Pathological EC-VSMC-myocyte communication (FN1-integrin, THBS4-CD36) perpetuates microvascular rarefaction. Therapeutic strategies include HIF1A stabilization (e.g., molidustat), THBS4 neutralization, and IRX2 targeting to restore vascular homeostasis.