Injectable tissue patch may help repair damaged heart

Scientists have developed an injectable tissue bandage smaller than a postage stamp that can repair damaged hearts.
Repairing heart tissue destroyed by a heart attack or medical condition with regenerative cells or tissues usually requires invasive open-heart surgery.
Researchers at the University of Toronto in Canada have developed a technique that lets them use a small needle to inject a repair patch, without the need to open up the chest cavity.
The AngioChip is a tiny patch of heart tissue with its own blood vessels and heart cells beating with a regular rhythm.
"If an implant requires open-heart surgery, it's not going to be widely available to patients," said Milica Radisic from University of Toronto.

She said that after a heart attack, the heart's function is reduced so much that invasive procedures like open-heart surgery usually pose more risks than potential benefits.

Miles Montgomery, a PhD candidate in Radisic's lab, has spent nearly three years developing a patch that could be injected, rather than implanted.
Researchers found a design that matched the mechanical properties of the target tissue, and had the required shape- memory behaviour: as it emerges from the needle, the patch unfolds itself into a bandage-like shape.
"The shape-memory effect is based on physical properties, not chemical ones," said Radisic.
This means that the unfolding process does not require additional injections and would not be affected by the local conditions within the body.

The next step was to seed the patch with real heart cells. After letting them grow for a few days, they injected the patch into rats and pigs.
Not only does the injected patch unfold to nearly the same size as a patch implanted by more invasive methods, the heart cells survive the procedure well.
Over time, the scaffold will naturally break down, leaving behind the new tissue.