Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous clinical syndrome linked to metabolic stress, systemic inflammation, hypertension, and microvascular dysfunction. Early, cell-type–specific events and the evolving intercellular signaling networks that accompany the onset and progression of HFpEF are not fully defined. This study applied time-resolved single-cell transcriptomics and complementary functional assays to map stage-dependent remodeling of the cardiac microenvironment during HFpEF progression in mouse models and to compare findings with human HFpEF data.
The authors used a longitudinal mouse model combining a high-fat diet and L-NAME (HFD+L-NAME) and sampled animals at control/baseline (0 weeks), early (1 week), intermediate (4 weeks), and established (8 weeks) stages. Comprehensive phenotyping included metabolic measurements, hemodynamics, exercise tolerance, echocardiography assessing diastolic filling with preserved ejection fraction, and single-cardiomyocyte functional assays focusing on calcium handling. Key physiologic and cellular dysfunctions—metabolic abnormalities, hypertension, reduced exercise capacity, abnormal diastolic filling with preserved EF, and altered cardiomyocyte calcium handling—were detectable by 1 week and persisted through 8 weeks.
Bulk RNA sequencing of cardiac tissue documented progressive remodeling across disease stages and showed limited additional change between 8 and 12 weeks. Those bulk transcriptional trajectories were used to inform selection of scRNA-seq timepoints for higher-resolution cell-type analyses.
Single-cell RNA sequencing was performed on cardiac non-cardiomyocyte populations, yielding transcriptional profiles for 94,848 cells. The analysis resolved nine major cell populations and demonstrated stage-dependent remodeling across cell types. Endothelial cells (ECs) were recovered at relatively high proportion and exhibited pronounced transcriptional dynamics early in disease. Other non-CM lineages, including fibroblasts and macrophages, showed progressive and temporally distinct activation programs.
By 1 week after HFpEF induction, endothelial cells showed a robust transcriptional response. The emergent programs included inflammatory signaling, increased expression of adhesion molecules, interferon-response pathways, migratory signatures, and vascular remodeling-associated transcripts. These early endothelial changes preceded large-scale fibroblast extracellular matrix remodeling and the progressive shift of macrophages toward inflammatory states.
Endothelial activation signatures identified in the HFD+L-NAME model were similarly observed in an L-NAME–independent model combining high-fat diet with mild transverse aortic constriction (HFD+mTAC). The authors also compared their endothelial signatures with a published human HFpEF single-nucleus RNA-seq cohort and reported related activation patterns, suggesting aspects of endothelial remodeling may translate across models and species.
To test whether HFpEF-like stressors directly promote endothelial activation and immune cell adhesion, the study used an endothelial–macrophage adhesion assay. Under HFpEF-mimic stress conditions, human endothelial cells increased adhesion molecule and chemokine expression and showed enhanced macrophage adhesion, providing functional support for the transcriptional evidence of early endothelial activation.
Fibroblast matrix-remodeling programs became more prominent at later stages of disease progression, following early endothelial activation. Macrophage populations displayed a progressive shift toward inflammatory transcriptional states over time. The temporal sequence reported is: early endothelial activation, followed by macrophage inflammatory remodeling and later fibroblast-driven matrix remodeling.
Using computational cell–cell communication inference (CellChat), the authors identified stage-dependent remodeling of intercellular signaling networks. Early disease stages were characterized by enriched endothelial–immune interactions, whereas later stages showed increased signaling between macrophages and fibroblasts. This temporal reconfiguration of signaling suggests a coordinated progression from microvascular activation to interstitial remodeling.
Time-resolved single-cell profiling in this HFpEF model reveals coordinated, stage-dependent remodeling of the cardiac microvascular and interstitial compartments. A central observation is that endothelial activation is an early event that precedes later fibroblast matrix remodeling and inflammatory remodeling of macrophages. Functional assays support the capacity of HFpEF-mimic stress to drive endothelial adhesion and immune recruitment. The dataset highlights candidate cell states and signaling pathways for mechanistic follow-up and potential therapeutic targeting.
Note: This work is reported as a preprint and has not been peer reviewed. Additional experimental and analytic details beyond those summarized here are those provided in the source preprint.