Attempting to reduce the risk for heart
failure following a
heart attack, early research on swine takes a new protective approach:
targeted injection of naturally occurring "protein inhibitors"
directly into the heart.
The invasive procedure has only been attempted on adult pigs, whose hearts
are considered comparable to that of humans.
But preliminary success in staving off heart failure in animal research
already amounts to a "proof of concept", the investigators said,
demonstrating that such a technique could work in people, too. And maybe even
improve upon current oral medications.
Study co-author Dr Francis Spinale, director of the Cardiovascular
Translational Research Centre at the University of South Carolina School of
Medicine, described how heart attacks can lead to heart failure in humans.
"The heart is composed of four chambers, with the one that pumps
oxygenated blood to the body termed the left ventricle," Spinale said.
"[And] a change in the shape of the left ventricle is one of the key
factors that physicians measure in patients following a heart attack.
"The stress of a heart attack typically sends problematic tissue-destroying
enzymes known as 'MMPs' into overdrive, while at the same time
blocking the activity of the body's helpful enzymes, known as 'TIMPs'," Spinale explained.
The result: a swelling of the left ventricle from football shape to
basketball shape, followed by structural collapse, he said. This ultimately
leads to heart failure, in which the heart loses the ability to pump sufficient
blood throughout the body.
This worst-case scenario, Spinale said, is the drive behind his team's
research: "to develop a strategy to restore the balance between MMPs and
TIMPs in hopes of stopping this left ventricle remodelling process after a
Spinale, who's also with Dorn Veteran Affairs Medical Centre in Columbia, SC,
and colleagues, published their findings in the issue of Science
Improved heart function
To rein in MMP activity, the investigators first combined a gelatin-type
recipe containing hyaluronic acid with a slow-releasing compound of a specific
TIMP called "TIMP-3".
Then, over a two-week period, the hearts of pigs that had been induced to
have a heart attack were injected with either the TIMP-3/hydrogel mix or a
non-medicinal saline solution.
In the weeks following a TIMP-3/hydrogel injection, the pigs that received
it were found to have improved heart
function, sidestepping the dangerous breakdown and reshaping of the heart's
The study team suggests that the new approach is a hopeful bet for human
patients, given the similarity of pig and human heart anatomy, and previous
indications that hydrogels can be safely injected into the human heart.
Experts note, however, that research with animals often fails to provide
similar results in humans.
Dr Nieca Goldberg, an American Heart Association spokeswoman, said it
remains to be seen just how effective the new hydrogel treatment will prove to
be in human patients.
"It's very important to talk about the fact that this is an animal
study, which means that it's not yet ready for prime time. But certainly this
is promising research," said Goldberg, medical director of the women's
heart programme at NYU Langone Medical Centre, in New York City.
"We're always looking for ways that we can avoid damage to the heart
muscle after a heart attack," she said. "Right now we use
[medications such as] ACE inhibitors and beta blockers to prevent heart
failure. Before those came on board as options, more people had heart failure
as a result of their heart attacks than is the case today.
"So this approach should be seen as another idea, an interesting
therapy for the future, that may help us continue to bring heart failure risk
further under control," Goldberg said.
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