Injecting Special Protein Could Make Hearts Heal Themselves

By Allison Bond | July 27, 2009 3:54 pm

heartInjecting a certain protein into mice and rats stimulated their heart cells to multiply after a heart attack, improving cardiac function. The experiment’s results point to a possible method to regenerate damaged human heart tissue, according to a study published in the journal Cell.

The adult heart is remarkably static. Although research this year revealed that a tiny number of new heart muscle cells are created in adulthood, that cellular regeneration tapers off throughout life, so heart damage inflicted during a heart attack does not heal naturally. But scientists found that injecting a growth factor called neuregulin1 (NRG1) into mice and rats stimulated the animals’ heart cells to divide. After 12 weeks of daily injections, the animals’ hearts showed less hypertrophy, or enlargement, and improved function. For instance, the hearts had about a 10 percent increase in ejection fraction–the fraction of blood pumped out of the left ventricle with each beat. The treatment “didn’t make the damage go away completely, … but it did make the heart work significantly better” [Technology Review], says lead researcher Bernhard Kühn.

Until now, efforts to repair heart tissue involved stem cells; the study is the first to explore a new approach to restore heart function. The researchers said it was not clear if NRG1 is directly responsible for the natural repair process – but their findings show it can clearly enhance it [BBC News]. Still, before the growth factor can be tested on humans, researchers must verify that the method is safe; the next step is to try the technique on pigs, which are physiologically closer to humans than are rodents. One concern is that because neuregulin 1 circulates throughout the entire body, it could cause undesired cell replication in breast tissue or the nervous system.

In the future, scientists may unite stem cell- and protein-based heart regeneration techniques. Some of the benefits of cell therapy may come from stimulating endogenous pathways similar to or the same as the one targeted by Kühn, says [stem cell scientist Joshua] Hare. It’s possible that part of the underlying biology is similar, he adds, and “we just have to figure out the best way to manipulate it” [Technology Review].

Related Content:
80beats: Could Stem Cells Patch Up a Broken Heart?
80beats: Researchers Could Grow Replacement Tissue to Patch Broken Hearts
80beats: Harvesting Infant Hearts for Transplants Raises Ethical Questions
80beats: The Upside of Nuclear Testing: Traceable Radioactivity in Our Heart Cells

Image: flickr / Patrick J. Lynch

CATEGORIZED UNDER: Health & Medicine


  • Angela

    Very exciting news! It seems to hold a great deal of promise for heart attack recovery, but I’ll remain cautiously optimistic until more research is done. Let’s make sure it won’t stimulate other cells (like cancer cells) to grow too!

    I’m also intrigued by the last sentence of the third paragraph: “it could cause undesired cell replication in breast tissue or the nervous system.” So it could potentially also cause breast cells to increase as well? Could this possible replace saline or silicon implants one day in the future? That could also be great news for women who’ve had mastectomies, as well as those seeking to supplement what nature provided. If, of course, the research pans out.

  • Allison Bond

    Dear Angela, this is Allison, the author of the post.

    Perhaps the wording in the third paragraph was a bit unclear… I’d like to clear up any confusion.

    The scientists are worried that the growth hormone could cause cell replication in certain tissues to go awry, possibly leading to an increased risk of cancer. It’s highly unlikely the injections would increase overall breast size.

    Thanks for reading!

  • Rigby

    Allison, are human trials of this procedure (assuming success with pigs) likely within a decade or can we hope for something sooner?

  • Angela

    Hi Allison,

    Thanks for clarifying. I assumed that the undesired cell replication was referring to cancer, and was being partially facetious while also wondering about breakthroughs in the cosmetic side of things.

    Thanks for the post!


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