Brown University Researchers have utilized computational models to design a new viscoelastic patch to reduce damage to heart tissue after a heart attack. They utilized a special blend of starch to help provide mechanical support to the heart tissue, which typically stretches after heart attack and results in poor heart function.
The investigators developed computational models of hearts beating and evaluated what kind of biomaterial patch would provide sufficient mechanical support. They used a biomaterial that was visco-elastic, which contains solid-like properties to provide stiffness and liquid-like properties to expand and flow in order to best support and accommodate the beating heart. When tested in rat models of heart failure, the researchers found improved heart function and reduced myocyte hypertrophy.
Providing Mechanical Support for Damaged Heart Tissue
“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, in an April 17 statement announcing the publication of a co-authored article, “A Viscoelastic Adhesive Epicardial Patch for Treating Myocardial Infarction,” in the publication, Nature Biomedical Engineering. “The idea here is to provide mechanical support for damaged tissue, which hopefully gives it a chance to heal,” says Gao.
The research, published in the biomedical journal, 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
“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,” notes Gao.
Gao added, “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,” says Liu. “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,” he notes.
Finding the Right Match
With those properties in hand, the Brown University Research 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.
The researchers say that the patch’s material is also cheap, costing less than a penny and easy to make. Experiments should that the fabric was nontoxic, too. 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 note, stressing that “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.”