Scientists believe they may have discovered a promising new way to treat heart disease in the future.
Fibres protect heart muscle cells
A study in rats suggests tiny protein fibres may be used to cut heart attack damage by stopping key cells, called cardiomyocytes, from dying.
A Harvard Medical School study showed injecting tiny fibres laced with a protective chemical into heart muscles kept the rats' organs working normally.
The study is published online by the Journal of Clinical Investigation.
Cardiomyocyte cells make up the middle muscle layer of the heart wall, called the myocardium, which does the work of pumping blood.
In normal heart muscle, the cardiomyocyte cells are nurtured by a complex network of tiny blood vessels called capillaries.
These vessels are lined by cells that secrete a chemical called PDGF-BB that keep the cardiomyocytes healthy.
However, when the blood vessels become narrowed or blocked, as they do as cardiovascular disease develops, the cardiomyocytes are starved of oxygen and begin to die.
Ultimately, this can lead to heart failure.
The Harvard team designed a method to inject the tiny microscopic or nanofibres coated with PDGF-BB into the myocardium of rats which suffered a heart attack.
Once there, the coated fibres were able to slowly release PDGF-BB into the damaged tissue area, the study showed.
This protected further cardiomyocytes from injury, kept damage down to a minimum, and helped to keep the heart working as normally as possible.
The Harvard team, lead by Drs Richard Lee and Patrick Hsieh, said the nanofibres held great potential as a way to deliver therapeutic agents directly to injured tissue.
Dr Lee told the BBC News website said the study could herald a new way of treating disease.
"For years we have been thinking about growing large pieces of tissue, or even whole organs, and then implanting them in patients.
"We are just beginning to think about promoting tissue repair and repair by harnessing control of cells on a micro and nano level.
"So controlled drug delivery or guidance of tissue repair from within the tissue itself is just starting, for the heart and for other tissues as well."
Professor Peter Weissberg, medical director at the British Heart Foundation, said the study was an interesting one which brought together new nanotechnology and cell biology to protect the heart.
"Basic biological research over recent years has identified a number of molecules that might protect the heart from the damage that occurs when its blood supply is interrupted, as occurs in a heart attack.
"The study represents the first step in a promising new way of treating heart disease in the future.
"However, a major challenge has been to deliver the right molecules to the site of injury in a way that offers protection over several days.
"What this research team has shown is that by linking a protective molecule to nanofibres they can prevent heart cells from dying when the blood supply is interrupted."