Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stem Cell Researchers Uncover Reason Why the Adult Human Heart Cannot Regenerate Itself

10.08.2011
Stem cell researchers at UCLA have uncovered for the first time why adult human cardiac myocytes have lost their ability to proliferate, perhaps explaining why the human heart has little regenerative capacity.

The study, done in cell lines and mice, may lead to methods of reprogramming a patient’s own cardiac myocytes within the heart itself to create new muscle to repair damage, said Dr. Robb MacLellan, a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA and senior author of the study.

Unlike newts and salamanders, human adults cannot spontaneously regrow damaged organs such as the heart. However, recent research suggests that mammals do have the ability to regenerate the heart for a very brief period, about the first week of life. But that ability is quickly lost. But if we had it once, MacLellan said, maybe it is possible to regain that ability.

Published in the Aug. 8 issue of the peer-reviewed Journal of Cell Biology, MacLellan’s study suggests it might be possible to turn back the cellular clock to a time when cardiac myocytes had the ability to proliferate and re-grow heart muscle.

“These salamanders and other lower organisms have the ability to de-differentiate cardiac myocytes, or take them back to an earlier, more primitive state, which allows them to re-enter the cell cycle, creating new heart muscle,” said MacLellan, who also is an associate professor of cardiology and physiology. “In mammals, we’ve lost that potential. If we knew how to restore that, or knew the reason why adult myocytes can’t do it, we could try to figure out a way to use nature’s methods to regenerate the heart.”

During human development, cardiac myocytes are made by progenitor stem cells and proliferate to form the heart. Once the heart is formed, the myocytes transform from immature cells into mature cells that cannot proliferate. That’s not so for newts and salamanders, whose cardiac myocytes can go back and forth between immature, or primitive, states to proliferate and repair damage and then revert back into mature cells once the damage is repaired.

MacLellan believes the reason adult human cardiac myocytes can’t do this is quite simple – when the myocytes are in a more primitive state, they are not as good at contracting, which is vital for proper heart function. Because humans are much larger than newts and salamanders, we needed more heart contraction to maintain optimum blood pressure and circulation.

“The way we evolved, in order to maintain blood pressure and flow we had to give up the ability to regenerate the heart muscle,” MacLellan said. “The up side is we got more efficient cardiac myocytes and better hearts. But it was a trade-off.”

MacLellan said that by temporarily knocking down the proteins that block the cell cycle mechanism, it may be possible to get adult cardiac myocytes to re-enter the cell cycle and revert to a state where they can again proliferate. These therapies would need to be reversible so that the effects of the protein manipulation eventually wear off once the damage is repaired. Then myocytes would become mature again and aid in contracting the regenerated heart muscle. MacLellan currently is looking into using nanoparticles to deliver small interfering RNA to the heart to knock out the proteins that are keeping the myocytes mature.

When a heart attack occurs, oxygen is cut off to part of the heart, causing the cardiac myocytes to die and resulting in scar tissue. It’s easy to locate the damaged area of the heart, and if a way could be developed to reprogram a patient’s own myocytes, the protein manipulation system could be injected into the damaged area, reverting the myocytes to their primitive state and replacing the dead muscle with new, living muscle, MacLellan said.

“People have been talking about the regenerative potential of these lower organisms for a long time and why this does not occur in humans” MacLellan said. “This is the first paper that provided a rationale and mechanism for why this happens.”

There has been much talk of using human embryonic stem cells or reprogrammed induced pluripotent stem cells to regenerate the heart. However, it’s unknown how much regeneration is possible and how much benefit would come from it.

“From my point of view, this is a potential mechanism to regenerate heart muscle without having to harvest or expand stem cells,” MacLellan said. “Each person would be their own source for cells for regeneration.”

The five-year study was funded by the National Institutes of Health.

The stem cell center was launched in 2005 with a UCLA commitment of $20 million over five years. A $20 million gift from the Eli and Edythe Broad Foundation in 2007 resulted in the renaming of the center. With more than 200 members, the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research is committed to a multi-disciplinary, integrated collaboration of scientific, academic and medical disciplines for the purpose of understanding adult and human embryonic stem cells. The center supports innovation, excellence and the highest ethical standards focused on stem cell research with the intent of facilitating basic scientific inquiry directed towards future clinical applications to treat disease. The center is a collaboration of the David Geffen School of Medicine, UCLA’s Jonsson Cancer Center, the Henry Samueli School of Engineering and Applied Science and the UCLA College of Letters and Science. To learn more about the center, visit our web site at http://www.stemcell.ucla.edu. To learn more about the center, visit our web site at http://www.stemcell.ucla.edu.

Kim Irwin | Newswise Science News
Further information:
http://www.ucla.edu
http://www.stemcell.ucla.edu

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>