A new biomaterial delivered to the heart shortly after a heart attack can heal damaged tissue from the inside out.
Heart attacks kill heart muscle tissue, scarring the heart and leaving irreversible damage after only six hours. The damage prevents the heart from functioning normally. If there was a way to start healing damaged tissue soon after a heart attack, doctors could prevent scar tissue from developing.
“In an ideal world, you would treat a patient right after they have a heart attack to try to save some of the tissue and promote regeneration,” says Karen Christman, a bioengineer at the University of California, San Diego.
The pursuit of this ideal inspired Christman and a team of researchers to develop the biomaterial. In rodents and pigs, it appears to repair tissue damage and reduce inflammation immediately after a heart attack, Christman and colleagues report Dec. 29 in Nature Biomedical Engineering .
“I think it has a lot of potential,” said Vimala Bharadwaj, a biomedical scientist at Stanford University who was not involved in the study. The paper “is definitely a good proof of concept for what they’re trying to do.”
Previously, researchers found that stem cells derived from body fat can be used to treat bones, muscles and the heart. Christman wanted to work with the extracellular matrix, a lattice of proteins that provide structural support for cells in heart muscle tissue. Like stem cells, it has the ability to regenerate, but costs much less, she says.
In 2009, Christman’s team produced a hydrogel using particles from this matrix. Tests on rats, and later on humans, showed that the material attaches to damaged areas and promotes cell repair and growth. However, due to the relatively large particles of the hydrogel, it could only be delivered to the heart using a needle.
“Putting a needle into the heart can cause an arrhythmia,” says Christman. Before using this treatment, doctors will need to wait a few weeks until the heart becomes more stable and the chances of these irregular heartbeats decrease. And it would be too late to prevent scarring.
The team took the previously created hydrogel, sifted out the larger particles using a centrifuge to leave only nanoparticles, and added water to dilute the mixture. This created a material thin enough to deliver blood vessels to the heart intravenously.
Based on the size of the nanoparticles, the team expected the mixture to slip through any gaps in the heart’s blood vessels caused by a heart attack and stick to the surrounding tissue. Once there, it will create a protective barrier until the heart heals.
Instead, animal experiments showed that the extracellular matrix material bound to leaky vessels, preventing some inflammatory cells from moving into heart tissue and causing further damage. The material reduced inflammation in the heart and stimulated the healing process by encouraging cell growth, the team reported.
Further safety studies will be required to prepare the biomaterial for clinical trials. The first human trial is likely to be for heart tissue repair after a heart attack. “A lot of my motivation is to get things out of the lab and into the real world,” Christman says.
Another real application of the biomaterial could be the treatment of leaky blood vessels in other hard-to-reach organs, including the brain after traumatic injury, Christman notes.
While Bharadwaj sees this application as potentially promising, she says tests are needed to see if the biomaterial improves headaches and cognitive impairment or memory deficits in the brain after a traumatic injury. This is necessary to assess whether it is truly an effective treatment for TBI.
