Damaged hearts may soon be treated using an injectable bandage, according to scientists at the University of Toronto.
Heart damage, such as tearing that can occur after a heart attack, is a serious and potentially fatal condition that requires surgical repair.
Over the past two decades, scientists have made staggering progress in engineering lab-grown tissues for such organ repair. These tissue repair patches are composed of non-toxic, biodegradable scaffolds on which living cells are grown. The patch is then placed directly onto the tear and over time the scaffold degrades, leaving behind the healthy tissue.
However, a key challenge of using tissue repair patches is that invasive surgery is required for their implantation. Such procedures often pose more potential risks than benefits to patients with organ damage, particularly those who have suffered a heart attack.
Professor Milica Radisic recognised that optimising the delivery of repair patches is key to ensuring that they can be safely and effectively used in patients. Therefore, her team got to work on developing the AngioChip, an injectable patch that could be delivered directly to the heart via keyhole surgery.
Inspired by the intricacies of computer chip manufacturing, Miles Montgomery, first author of the study, worked on perfecting the design of the AngioChip for three years. The key challenge was to create a structure that allows the patch to ‘remember its shape’, meaning that it can unfold and cover the damaged area post injection.
The AngioChip’s hand-built 3D scaffold is composed of a series of thin elastic layers, which resemble computer microchips. This complex microstructure allows the patch to regain its original shape after being passed through a 1mm needle.
In addition to this ‘shape memory’, the researchers also needed to test whether or not their scaffold was biomedically compatible - in other words, could it support the growth of functional tissue cells?
To test this, the scaffold was bathed in a liquid containing functional human heart cells, called cardiomyocytes. Reassuringly, these cells quickly attached to the layers of the scaffold and began growing and functioning as they would in the human body - they even had a rhythmic beat.
The AngioChip was then injected onto damaged liver and heart tissue within pigs and rats. The exciting results, published in Nature Materials, show that the AngioChip unfolds to the same size as an implanted repair patch and crucially, the implanted cells retain their functionality after injection, meaning that they can repair the damaged organ. Furthermore, the study also shows that injecting the patch into rat hearts improves cardiac function after a heart attack.
Although there is still quite a long way to go before clinical trials begin, the injectable AngioChip is setting the pace for non-invasive tissue repair.
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