University of Toronto, Canada, biomedical engineers are looking to make invasive open-heart surgery a The flexible tissue scaffold is shown emerging from a glass pipette with a tip one millimeter wide. Source: Miles Montgomery and Rick Luprocedure of the past. The team developed an expanding tissue scaffold that can be delivered by needle injection as a repair patch.

The shape-memory scaffold composed of a biodegradable polymer unfolds itself following injection. This technology could offer a minimally invasive option to reduce recovery time and risks for heart attack patients.

After being seeded with real heart cells, postage stamp-size patches were injected into rats and pigs. The patches were observed to unfold to nearly the same size as one implanted by more invasive methods, and the heart cells remained viable. Over time, the scaffold will naturally break down, leaving behind the new tissue.

Injecting the patch into rat hearts was also shown to improve cardiac function after a heart attack: damaged ventricles pumped more blood than they did without the patch.

The long-term stability of the patches is now under study, as is whether the improved cardiac function can be maintained.