Single Protein PHF7 Repairs Hearts After Heart Attack by Converting Scar Tissue
Breakthrough study shows one epigenetic factor can transform cardiac fibroblasts into heart muscle cells, improving function after myocardial infarction.
Summary
Researchers discovered that a single epigenetic protein called PHF7 can convert scar-forming fibroblasts into functional heart muscle cells after heart attack. When injected into mouse hearts following myocardial infarction, PHF7 alone improved cardiac function, reduced fibrosis, and increased survival rates. This represents a major advance in cellular reprogramming therapy, as previous approaches required multiple factors with limited success. The protein works by modifying chromatin structure to activate cardiac gene programs, essentially rewiring cell identity at the molecular level.
Detailed Summary
Heart disease remains the leading cause of death worldwide, largely because the adult human heart cannot regenerate lost muscle tissue after injury. When heart attacks occur, dead heart muscle is replaced by scar tissue (fibroblasts), which cannot contract and pump blood effectively.
Researchers at UT Southwestern made a breakthrough discovery: a single epigenetic protein called PHF7 can reprogram cardiac fibroblasts into functional heart muscle cells (cardiomyocytes). Previous cellular reprogramming attempts required cocktails of 3-5 transcription factors with poor efficiency, making clinical translation challenging.
In laboratory studies, PHF7 successfully converted 10% of adult mouse fibroblasts into heart muscle-like cells when combined with just one other factor (Tbx5). More remarkably, when PHF7 was injected alone into mouse hearts immediately after induced heart attacks, it improved cardiac function by 15-20 percentage points, reduced harmful remodeling, and significantly increased survival rates over 16 weeks.
Using advanced single-cell genomics, researchers discovered PHF7 works by binding to specific DNA regions and reorganizing chromatin structure, activating master cardiac genes while suppressing fibroblast programs. The protein essentially rewires cellular identity at the molecular level, transforming scar-forming cells into contractile heart muscle.
This represents the first demonstration of single-factor cardiac reprogramming working effectively in living hearts after injury. The approach could potentially be developed into an injectable therapy for heart attack patients, offering hope for actual heart muscle regeneration rather than just symptom management.
Key Findings
- PHF7 alone improved heart function 15-20% and survival after heart attack in mice
- Single protein converted 10% of fibroblasts to heart muscle cells in lab studies
- Treatment reduced cardiac fibrosis and improved remodeling for 16 weeks
- PHF7 works by reorganizing chromatin to activate cardiac gene programs
- First successful single-factor approach for cardiac cellular reprogramming
Methodology
Researchers used permanent LAD artery ligation in mice to induce myocardial infarction, then injected retroviral PHF7 directly into ischemic myocardium. Cardiac function was assessed via serial echocardiography, with genetic lineage tracing to confirm fibroblast-to-cardiomyocyte conversion.
Study Limitations
Study conducted only in mice; human cardiac fibroblasts may respond differently. Long-term safety and optimal delivery methods for clinical use remain to be established. Efficiency of reprogramming, while improved, is still relatively modest at 10%.
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