Cardiac patch for a broken heart
People who suffered from heart attacks or other heart failures often need transplants because their hearts are essentially non-functioning. But imagine what will happen if it was possible to engineer living heart tissues to fix these broken hearts. This is what bioengineers at Columbia University Medical Center in New York City are starting to make. According to HealthDay News, their patches for broken hearts are made of heart tissue grown in the lab. Right now, animal trials are just starting and it will take at least a decade before human trials begin. But when these living bandages are ready for cardiac care, they'll have the potential to save millions of lives in the world every year.
HealthDay News uses the expression 'hybrid hearts' while the researchers seem to prefer to use 'broken hearts.'
"We joke that this is really 'a patch for a broken heart,'" said Gordana Vunjak-Novakovic, professor of biomedical engineering at Columbia University Medical Center in New York City, and co-director of the Tissue Engineering Resource Center at the National Institutes of Health in Bethesda, Md.
Here is why they started to develop these living heart tissues.
Hearts affected by heart attack or congestive heart failure develop large areas of scar tissue that is essentially non-functioning. In the most serious cases, drugs are of little help, and demand for heart transplants far outstrip the supply of donor hearts.
"So, we are trying here to make heart tissue," Vunjak-Novakovic explained. The process mimics that seen in nature, with scientists replicating the cardiac environment inside a special tissue-growing chamber called a bioreactor.
The image below shows one experimental cardiac patch (Credit: Harvard-MIT Division of Health Sciences and Technology). Here is a link to a larger version. "In the next stage of their research, the scientists will place the beating, dime-sized piece of heart tissue over damaged heart tissue, so it can take over the damaged tissue's function. To date, the scientists have proved that this procedure works with rats' heart cells." (Credit for caption: Museum of Science, Boston, MA).
It looks like it's really difficult to grow these tissues successfully.
Everything has to be right: Cardiac cells must grow at a very high density but also be well-oxygenated, just as they are in the developing heart. And those cells must also be artificially electrically stimulated, since it is electric pulses that keep hearts beating.
But the researchers have made good progress and animal trials are already under way.
For more information, the basis for this research work has been published by the Proceedings of the National Academy of Sciences under the name "Functional assembly of engineered myocardium by electrical stimulation of cardiac myocytes cultured on scaffolds" (Vol. 101, No. 52, Pages 18129-18134, December 28, 2004). Here is a link to the abstract.
It still will take more than ten years before human trials can start. But one day, this cardiac patch might become a routine part of cardiac care, according to Gordana Vunjak-Novakovic.
Sources: E.J. Mundell, HealthDay News, January 20, 2006; and various web sites
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