Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How fish mend a broken heart

03.11.2006
New evidence to explain how a common tropical fish mends a broken heart may suggest methods for coaxing the damaged hearts of mammals to better heal, researchers report in the November 3, 2006 issue of Cell, published by Cell Press.

The researchers found that the hearts of zebrafish harbor progenitor cells that spring into action to restore wounded heart muscle. Cells from a membrane layer that surrounds the heart, called the epicardium, follow suit, invading the wounded cardiac tissue and stimulating the growth of new blood vessels.

"Zebrafish can survive pretty massive injury to the heart--the loss of about a quarter of their ventricle," said Kenneth Poss of Duke University Medical Center. The ventricle, which receives blood and then pumps it back out to the body, is one of two chambers that make up the fish heart. "This study gets at some of the important mechanistic questions about how they rebuild the heart, and some of the key factors that contribute."

In contrast to zebrafish, the cardiac damage and scarring caused by heart attacks is a major killer among humans, making "the inability to replace damaged cardiac muscle one of the most prominent regenerative failures of mammals," wrote Alexandra Lepilina and Ashley Coon, the study's first authors.

However, mammalian hearts have been found to contain rare populations of progenitor cells, they added. As in zebrafish, the hearts of adult mammals, including humans, are also housed inside an epicardium, a tissue about which little is known.

"Scientists haven't paid much attention to the epicardium in adults," Poss said. "These findings in fish should encourage more exploration of what adult epicardium can do.

"There is the potential that these cells could be utilized for therapies."

The ability to regenerate tissue is a feature shared among vertebrate species, the researchers said. However, particular animals, including certain amphibians and fish, display an "elevated regenerative spectrum, with many more tissues capable of impressive regeneration," they said. For instance, certain newts or salamanders can regenerate limbs, spinal cord, retina, brain, and heart tissue.

While progenitor cell populations have been identified within most mammalian organs, including skin, skeletal muscle, brain, and heart, these cells vary widely in frequency and the ability to regenerate damaged or lost tissue, they said. In most mammalian organs, progenitor cells can restore cells lost in the course of normal organ function or after minor injury but cannot regenerate after major damage or removal of structures.

"It is believed that the capacity for regeneration is an ancestral condition that has occasionally been lost in the course of vertebrate evolution." Poss said. "Thus, most biologists suspect that the machinery to optimize regeneration from progenitor cells is present, but lies dormant, in mammals."

In an earlier study, Poss and his colleagues found that zebrafish have a unique ability to regenerate cardiac muscle after major injury. They further suspected that illumination of the fishes' ability might offer important insights into "how heart regeneration is naturally optimized."

In the current study, they found that heart regeneration proceeds through two coordinated stages. First, a mass of undifferentiated, pre-cardiac cells form. Those progenitor cells then begin to differentiate and divide, to replace the damaged heart muscle.

In the second step, the epicardium surrounding the heart chambers "lights up" with activity as developmental genes switch on, Poss said. The epicardium expands to rapidly cover the wounded heart muscle.

A subset of those epicardial cells then alters their identity, invading the wound and providing essential new blood vessels to the growing muscle.

They further found that the two-part regeneration process is coordinated by so-called "fibroblast growth factor" (Fgf) signals. Fgf signals are known for their ability to encourage invasive cell behavior, Poss explained.

Indeed, they found, heart muscle cells produce the growth factor, while epicardial cells harbor receptors that are triggered by the signal. When the researchers experimentally blocked the Fgf signal, heart regeneration failed.

"It is tempting to speculate that the ability to mobilize epicardial cells and cultivate such a cardiogenic environment is a primary reason why zebrafish, as opposed to other laboratory models, effectively regenerate [heart muscle]," the researchers concluded. Indeed, they added, mammalian hearts typically show insufficient blood vessel growth after a heart attack.

"Experimental attempts to modify this deficiency are underway, including delivery of growth factors or bone marrow-derived cells that may promote [the formation of new blood vessels]…Success in these pursuits or by directly utilizing epicardial cells or their progenitors could prove favorable for encouraging regeneration from mammalian cardiac progenitor cells."

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>