Heart patch
could limit muscle damage in heart attack aftermath
Researchers have designed a new type
of adhesive patch that can be placed directly on the heart and may one day help
to reduce the stretching of heart muscle that often occurs after a heart
attack.
The patch, made from a water-based hydrogel
material, was developed using computer simulations of heart function in order
to fine tune the material’s mechanical properties.
A study in rats showed that the patch was effective in preventing left ventricle remodeling — a stretching of the heart muscle that’s common after a heart attack and can reduce the function of the heart’s main pumping chamber.
The research also showed that the computer-optimized patch outperformed patches whose mechanical properties had been selected on an ad hoc basis.
A study in rats showed that the patch was effective in preventing left ventricle remodeling — a stretching of the heart muscle that’s common after a heart attack and can reduce the function of the heart’s main pumping chamber.
The research also showed that the computer-optimized patch outperformed patches whose mechanical properties had been selected on an ad hoc basis.
The research, published in Nature
Biomedical Engineering, was a collaboration between computer
modeling and mechanics researchers in Brown University’s School of Engineering,
cardiology researchers from Fudan University and material scientists from
Soochow University.
“Part of the reason that it’s hard for the heart to recover after a heart attack is that it has to keep pumping,” said Huajian Gao, a professor of engineering at Brown and a co-author on the paper. “The idea here is to provide mechanical support for damaged tissue, which hopefully gives it a chance to heal.”
Prior research had shown that
mechanical patches could be effective, the researchers say, but no one had done
any research on what the optimum mechanical properties of such a patch might
be. As a result, the thickness and stiffness of potential patches varies
widely. And getting those properties right is important, Gao says.
Hearts with with the computer
optimized patch (second column from the left) remodeled less that those with no
patch at all (far left column) and hearts patched with suboptimal properties
(right columns).
“If the material is to hard or
stiff, then you could confine the movement of the heart so that it can’t expand
to the volume it needs to,” he said. “But if the material is too soft, then it
won’t provide enough support. So we needed some mechanical principles to guide
us.”
To develop those principles, the
researchers developed a computer model of a beating heart, which captured the
mechanical dynamics of both the heart itself and the patch when fixed to the
heart’s exterior. Yue Liu, a graduate student at Brown who led the modeling
work, says the model had two key components.
“One part was to model normal heart
function — the expanding and contracting,” Liu said. “Then we applied our patch
on the outside to see how it influenced that function, to make sure that the
patch doesn’t confine the heart. The second part was to model how the heart
remodels after myocardial infarction, so then we could look at how much
mechanical support was needed to prevent that process.”
With those properties in hand, the
team turned to the biomaterials lab of Lei Yang, a Brown Ph.D. graduate who is
now a professor at Soochow University and Hebei University of Technology in
China.
Yang and his team developed a hydrogel material made from food-sourced starch that could match the properties from the model.
The key to the material is that it’s viscoelastic, meaning it combines fluid and solid properties. It has fluid properties up to a certain amount of stress, at which point it solidifies and becomes stiffer.
That makes the material ideal for both accommodating the movement of the heart and for provided necessary support, the researchers say.
Yang and his team developed a hydrogel material made from food-sourced starch that could match the properties from the model.
The key to the material is that it’s viscoelastic, meaning it combines fluid and solid properties. It has fluid properties up to a certain amount of stress, at which point it solidifies and becomes stiffer.
That makes the material ideal for both accommodating the movement of the heart and for provided necessary support, the researchers say.
The material is also cheap (a patch
costs less than a penny, the researchers say) and easy to make, and experiments
showed that it was nontoxic. The rodent study ultimately showed that it was
effective in reducing post-heart attack damage.
“The patch provided nearly optimal
mechanical supports after myocardial infarction (i.e. massive death of
cardiomyocytes),” said Ning Sun, a cardiology researcher at Fudan University in
China and a study co-author. “[It] maintained a better cardiac output and thus
greatly reduced the overload of those remaining cardiomyocytes and adverse
cardiac remodeling.”
Biochemical markers showed that the
patch reduced cell death, scar tissue accumulation and oxidative stress in
tissue damaged by heart attack.
More testing is required, the
researchers say, but the initial results are promising for eventual use in
human clinical trials.
“It remains to be seen if it will
work in humans, but it’s very promising,” Gao said. “We don’t see any reason
right now that it wouldn’t work.”
Other coauthors on the paper were
Xiao Lin, Aobing Bai, Huanhuan Cai, Yanjie Bai, Wei Jiang, Huilin Yang and
Xinhong Wang. The work was supported by National Natural Science
Foundation of China and the U.S. National Science Foundation (CMMI-1562904).
