Newts can regrow a limb. Some lizards can sprout new tails. Even humans can replace some damaged tissue in organs, such as the liver. But none can accomplish what the zebra fish, a common denizen of home aquariums, can do: regenerate their hearts. Biologists have long known about the zebra fish's cardiac ability, and now researchers think they have unlocked the secret of the process, which may provide essential clues for human heart repair.

Kenneth Poss and his colleagues at Duke University found that zebra fish, Danio rerio, regenerate heart muscle in two synchronized steps. Within five days of removing about 20 percent of an adult zebra fish heart ventricle, undifferentiated progenitor cells begin to line the injured area and turn into cardiac muscle cells, which grow and divide, building new heart muscle. Meanwhile, developmental genes in the epicardium--a cell layer that surrounds the entire heart and influences embryonic heart development--switch on, activating the epicardial cells. Most of these cells form a new layer to cover the wound and the regenerating heart muscle, but some also create blood vessels for the growing muscle, "fulfilling the same role as they do when the embryonic heart develops," Poss says.

A growth factor signal orchestrates the two processes so that they converge to mend the zebra fish heart, according to the study that appears in the November 3 issue of Cell. This chemical, produced by the heart muscle cells, activates receptors on the surface of the epicardial cells, signaling it to form a new heart lining. If the communication between the two cell types is blocked, the zebra fish heart starts to scar and cannot completely regenerate.

Like zebra fish, mammal hearts have progenitor cells and an epicardium, but the formers "found a way to regenerate effectively," Poss says. The regenerative mechanism discovered in this fish could "give people who are eager to repair human hearts a pathway to hone in on," says Deborah Yelon, a researcher at New York University who studies zebra fish but was not involved in the study. The current findings suggest strategies that can be tested in human hearts, such as introducing growth factors and activating the receptors on epicardial cells, she says. "Maybe we can get mammalian progenitor cells to behave more like zebra fish cells," she adds. The study also highlights the role of the epicardium, a cell layer that is studied extensively in zebra fish embryonic development but receives little attention in adults. Poss hopes that researchers will also "take a closer look at the epicardium in injured mammalian hearts and to potentially look at whether epicardial cells can be used therapeutically."

3 Comments

1. 1. ldelre 09:03 PM 4/9/09

   By measuring heart tissue levels of a carbon isotope absorbed by all living creatures after above-ground atom bomb tests during the 1950's, researchers found that, contrary to conventional wisdom, heart cells slowly replace themselves over the course of a lifetime.
   
   Citations: "Evidence for Cardiomyocyte Renewal in Human." By Olaf Bergmann, Ratan D. Bhardwaj, Samuel Bernard, SofiaZdunek, Fanie Barnab�-Heider, Stuart Walsh, Joel Zupicich, Kanar Alkass, BruceA. Buchholz, Henrik Druid, Stefan Jovinge, Jonas Fris�n. Science, Vol. 324, April 3, 2009.
   
   Turnover After the Fallout." By Charles E. Murray and Richard T. Lee. Science, Vol. 324, April 3, 2009.
   
   The above info was found at:
   http://blog.wired.com/wiredscience/2009/04/newheartcells.html?cid=152033457#comment-152033457

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2. 2. elitehealth 04:25 AM 6/4/09

   Its like a really surprising blog for any one who is suffering from heart disease. If we would be able to somehow regenerate the heart muscles in humans, by studying the zebra fish, which would be considered as a revolutionary move in the field of healthcare and medicine. But the rate at which damage occurs to the heart cells might be beyond their recovery cycle. So, though it might not be that helpful in recovery as soon as we find it, but still for youngsters, it can be like a boon. I was having a blockage on the coronary arteries, and was on the verge of getting damaged. I was really unaware of that blockage since a long time until my physician asked me to get a heart scan done after he found that my basic cardiograms were not perfect. I discovered that there were calcium deposits in my coronary arteries and I was at a serious risk of a heart attack. I was shocked and went ahead with the Cardiologist's suggestion of an advanced diagnostic scan. Though its always tough to undergo such experiences, I was not at any kind of discomfort at the Elitehealth.com advanced heart scan facility. I am not an expert in medical appliance and machines but could feel that the equipment was world-class and I was in safe hands. That feeling is really very important for me and thats how it actually went on. The facilities for Full Body Scan were as good as they can get.

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3. 3. Darkend Warrior 11:37 AM 11/11/09

   I never knew that lol It's creepy
   

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