Biomedical engineers at Duke University have created a fully functioning artificial human heart muscle large enough to patch over damage typically seen in patients who have suffered a heart attack, according to a new study published in the journal Nature Communications.
Unlike some human organs, the heart cannot regenerate itself after a heart attack. The dead muscle is often replaced by scar tissue that can no longer transmit electrical signals or contract, both of which are necessary for smooth and forceful heartbeats.
Current clinical trials are testing the tactic of injecting stem cells derived from bone marrow, blood or the heart itself directly into the affected site in an attempt to replenish some of the damaged muscle. However, fewer than one per cent of the injected cells survive and remain in the heart, and even fewer become cardiac muscle cells.
Heart patches, on the other hand, could conceivably be implanted over the dead muscle and remain active for a long time, providing more strength for contractions and a smooth path for the heart’s electrical signals to travel through.
For this approach to work, however, a heart patch must be large enough to cover the affected tissue. It must also be just as strong and electrically active as the native heart tissue, or else the discrepancy could cause deadly arrhythmias. This is the first human heart patch to meet both criteria.
The researchers have successfully shown that these cardiac patches survive and maintain their function when implanted onto mouse and rat hearts.
Ilya Shadrin, the study’s first author, said: ‘Right now, virtually all existing therapies are aimed at reducing the symptoms from the damage that’s already been done to the heart, but no approaches have been able to replace the muscle that’s lost, because once it’s dead, it does not grow back on its own.’
‘This is a way that we could replace lost muscle with tissue made outside the body. Creating individual cardiac muscle cells is pretty commonplace, but people have been focused on growing miniature tissues for drug development. Scaling it up to this size is something that has never been done and it required a lot of engineering ingenuity.’