Two new studies suggest that heart muscle cells can make copies of themselves at a very low rate, but researchers have developed a genetic trick that prompts them to improve their efficiency.
The scientists published their findings in two papers in the journal Nature. This could imply that hearts may be coaxed into healing themselves. Richard Lee and his colleagues at the Brigham and Women’s Hospital and Harvard Medical School, Boston Massachusetts, traced the birth and fate of heart muscle cells in mice. They found that less than 1% can regenerate themselves normally. After a heart attack this proportion goes up, but only to 3%.
The heart doesn’t have a robust ability to regenerate, however, the existence of such cells gives hope that the heart might have some capacity for new heart muscle cells. The second paper was able to improve the efficiency of this process by using microRNAs to stimulate heart cells into regenerating.
Hundreds of microRNAs were screened for the ability to prompt mouse and rat heart cells to multiply. Heart attacks were induced into live mice and it was shown that two particular microRNAs helped build the damaged hearts back up again so that they were almost functioning normally again. After two months, the area of the tissue killed by the heart attack was reduced by half, improving blood flow.
These microRNAs need further testing in larger animal models that have more human-like hearts before any clinical consideration is prompted.
“Mammalian heart renewal by pre-existing cardiomyocytes” by Samuel E. Senyo, Matthew L. Steinhauser, Christie L. Pizzimenti, Vicky K. Yang, Lei Cai, Mei Wang, Ting-Di Wu, Jean-Luc Guerquin-Kern, Claude P. Lechene and Richard T. Lee, 5 December 2012, Nature.
“Functional screening identifies miRNAs inducing cardiac regeneration” by Ana Eulalio, Miguel Mano, Matteo Dal Ferro, Lorena Zentilin, Gianfranco Sinagra, Serena Zacchigna and Mauro Giacca, 5 December 2012, Nature.