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Updated: Apr 11, 2026
In Vitro Culture of Epicardial Cells From Mouse Embryonic Heart
Published on: April 27, 2016
Human epicardial cell-conditioned medium contains HGF/IgG complexes that phosphorylate RYK and protect against
Krithika S Rao1, Alexander Aronshtam2, Keara L McElory-Yaggy2
1Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Colchester, VT, USA Department of Medicine and Cardiovascular Research Institute, University of Vermont, 208 South Park Drive, Ste 2, Colchester, VT 05446, USA.
Insights
Human epicardial-derived cells secrete factors that protect blood vessels. A novel HGF/IgG complex enhances this protection by activating specific receptors, offering a new therapeutic approach for vascular reperfusion injury.
Area of Science:
- Cardiovascular Biology
- Regenerative Medicine
- Cell Signaling
Background:
- Epicardial cells play a crucial role in cardiac repair and remodeling through paracrine signaling.
- Vascular integrity is compromised after myocardial infarction (MI) with reperfusion, necessitating protective strategies.
Purpose of the Study:
- To investigate the paracrine activity of human epicardial-derived cells (hEPDCs) for vasoprotective factors.
- To develop novel therapeutics for vascular reperfusion injury using identified factors.
Main Methods:
- Cultured hEPDCs and treated primary cardiac endothelial cells with conditioned medium (EPI CdM).
- Utilized a rat MI model to assess in vivo efficacy of EPI CdM.
- Employed phospho-receptor tyrosine kinase (RTK) arrays, ELISA, and antibody screens to identify key factors and signaling pathways.
Main Results:
- hEPDC-conditioned medium (EPI CdM) enhanced endothelial cell survival and reduced vascular injury post-reperfusion.
- Hepatocyte growth factor (HGF) was identified as a key vasoprotective factor within EPI CdM.
- HGF/IgG complexes demonstrated superior vascular protection compared to free HGF, promoting RYK receptor phosphorylation and increasing HGF retention.
Conclusions:
- HGF/IgG complexes represent a novel therapeutic strategy for mitigating vascular reperfusion injury.
- Early administration of HGF/IgG complexes may protect tissue via c-Met and RYK signaling pathways.
- This study highlights the potential of engineered HGF complexes for cardiovascular therapeutics.
Aims:
The aim of this study was to evaluate the paracrine activity of human epicardial-derived cells (hEPDCs) to screen for secreted vasoprotective factors and develop therapeutics to treat vascular reperfusion injury.
Methods And Results:
Epicardial cells support cardiac development, repair, and remodelling after injury in part, through paracrine activity. We hypothesized that secreted ligands from hEPDCs would protect vascular integrity after myocardial infarction (MI) with reperfusion. During simulated ischaemia in culture (24-48 h), concentrated hEPDC-conditioned medium (EPI CdM) increased survival of primary cardiac endothelial cells. In a rat MI model, EPI CdM treatment reduced vascular injury in vivo after reperfusion. By phospho-receptor tyrosine kinase (RTK) arrays, ELISA, and neutralizing antibody screens, we identified hepatocyte growth factor (HGF) as a key vasoprotective factor in EPI CdM. Unexpectedly, we observed that some of the HGF in EPI CdM formed complexes with polyclonal IgG. Following reperfusion, preparations of HGF/IgG complexes provided greater vascular protection than free HGF with IgG. HGF/IgG complexes localized to blood vessels in vivo and increased HGF retention time after administration. In subsequent screens, we found that 'related to tyrosine kinase' (RYK) receptor was phosphorylated after exposure of cardiac endothelial cells to HGF/IgG complexes, but not to free HGF with IgG. The enhanced protection conferred by HGF/IgG complexes was lost after antibody blockade of RYK. Notably, the HGF/IgG complex is the first 'ligand' shown to promote phosphorylation of RYK.
Conclusion:
Early treatment with HGF/IgG complexes after myocardial ischaemia with reperfusion may rescue tissue through vasoprotection conferred by c-Met and RYK signalling.
