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Simultaneous studies into heart cell regeneration offer hope for heart attack victims

Together the studies could lead to a way to help the heart regeneration itself following a heart attack, and offer new hope for the 17 million people who die from cardiovascular disease each year.

“The question of how cardiac cells are born has been extremely difficult to answer because there was a need for new techniques to help us understand this process,” said Richard T. Lee, M.D., of BWH’s Cardiovascular Division and senior author of the paper on the origination of heart muscle cells. The study was published Dec. 5 in the online issue of Nature.

“These data present one piece of the puzzle when it comes to the discussion around the generation of new cardiac cells,” he added.

The team of BWH researchers used multi-isotope imaging mass spectrometry (MIMS), a technology developed by team collaborator Claude Lechene, M.D., to examine the development of new heart muscle cells in a mouse model over a period of months. They were surprised to find that new heart muscle cells primarily arose from existing heart muscle cells, rather than from stem cells.

Even in the setting of a heart attack, when stem cells are thought to be activated, most new heart cells were born from pre-existing heart cells, they reported.

However, only a small proportion of heart cells — less than 1 percent — were found to regenerate normally. After a heart attack that proportion goes up slightly, to 3 percent.

Boosting that capacity would be essential to developing this approach as a therapy for cardiovascular disease. A separate study, released in same issue of Nature, revealed a genetic trick that can do just that.

This work, led by Mauro Giacca of the International Centre for Genetic Engineering and Biotechnology in Trieste, Italy, used microRNAs to stimulate heart cells to start regenerating.

After screening hundreds of microRNAs for the ability to prompt mouse and rat heart cells to proliferate, the researchers induced heart attacks in mice and showed that two particular microRNAs helped to rebuild the damaged hearts so that they were functioning almost normally.

Two months later, the area of tissue killed off by the heart attack was reduced by half and the heart’s capacity to pump blood had significantly improved.

The next step involves testing the microRNAs in larger animals with more human-like hearts, the research team said.

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