Scientists create a nanopatch for the heart

Posted by Chris Nova

When you have a heart attack, a part of your heart dies. Specialized heart cells perish and you can never get them back.

Doctors cannot repair these kinds of areas in the heart; the dead areas just sit there functioning no more. When confronted with this type of problem there doesn’t seem to be much of a solution. Do you treat the area like a pothole and build a new route around it?
    
You could, but that’s a really unproductive way to fix the most important organ in the human body. In theory, a better approach would be to figure out how to revive the lifeless area. A group of researchers at Brown University and in India may have figured out a way to do exactly that.
    
The scientists looked to nanotechnology for a solution.
    
In a laboratory they constructed a scaffold-looking structure made of carbon nanofibers and a government-approved polymer. Their tests showed the artificial nanopatch restarted natural heart tissue cells ­– called cardiomyocytes – as well as neurons. Bascially, the tests showed that a dead region of the heart can be brought back to life. That’s right; we’re talking about zombie style hearts.
    
"This whole idea is to put something where dead tissue is to help regenerate it, so that you eventually have a healthy heart," said David Stout, a graduate student in the School of Engineering at Brown and the lead author of the paper published in Acta Biomaterialia.
    
The method, if successful, would help millions of people with dead spots in their hearts. In 2009, about 785,000 Americans suffered a new heart attack because of a weakness caused by the scarred cardiac muscle from an earlier heart attack, according to the American Heart Association. Equally worrisome is the estimation that a third of women and a fifth of men who have experienced a heart attack will have another one within six years, the researchers added, citing the American Heart Association.
    
The interesting thing about the experiments at Brown and at the India Institute of Technology Kanpur is that the engineers employed carbon nanofibers, helical-shaped tubes with thicknesses between 60 and 200 nanometers. The carbon nanofibers function well since they are excellent conductors of electrons, carrying out the kind of electrical connections the heart needs to keep a steady beat.

The researchers sewed the nanofibers together using a poly lactic-co-glycolic acid polymer to form a mesh about 22 millimeters long and 15 microns thick and reminding one of "a black Band Aid," Stout said. They laid the mesh on a glass substrate to see whether or not the cardiomyocytes would colonize the surface and grow more cells.

In tests using the 200-nanometer-diameter carbon nanofibers seeded with cardiomyocytes, they saw five times as many heart-tissue cells had colonized the surface after four hours compared to a control sample made up of the polymer only. After five days, the thickness of the surface was six times larger than the control sample, the researchers reported. Neuron density had also doubled after four days, they added.

The scaffold works since it is elastic and durable, and can therefore expand and contract just like heart tissue, said Thomas Webster, associate professor in engineering and orthopaedics at Brown and the corresponding author on the paper. It's because of these properties and the carbon nanofibers that cardiomyocytes and neurons assemble on the scaffold and make new cells, in effect regenerating the area.

The scientists want to tinker with the scaffold pattern so that they can better mimic the electrical current of the heart, as well as build an in-vitro model to test how the material responds to the heart's voltage and beat system. They also want to make certain the cardiomyocytes that grow on the scaffolds possess the same abilities as other heart-tissue cells.