Researchers at University College London studied thymosin beta-4, a peptide involved in building the heart's blood vessels before birth, to see whether it could reactivate that dormant outer layer, called the epicardium, in adult heart tissue.
The peer-reviewed study found that in developing mice, knocking down thymosin beta-4 crippled the growth of the heart's own blood vessels. In culture, the peptide made quiet adult epicardial tissue sprout and turn into fibroblasts, smooth muscle and blood vessel lining cells, the building blocks of new vessels.
The authors proposed that these reawakened cells could supply new vessels after heart injury, but this paper showed the effect in embryos and in adult tissue in a dish, not in a living injured heart. Later work tested the idea in mice after heart attacks, with more modest results when it came to rebuilding lost muscle.
Read the original study
A dormant layer, switched back on in a dish.
Source
- Smart, N., Risebro, C. A., Melville, A. A. D., Moses, K., Schwartz, R. J., Chien, K. R., & Riley, P. R. (2007). Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature, 445(7124), 177–82. https://doi.org/10.1038/nature05383