New ‘Velcro’ tissue could help repair damaged hearts

Toronto: Researchers have made assembling functional heart tissue easier by creating a biocompatible scaffold that allows sheets of beating heart cells to snap together just like Velcro.

“One of the main advantages is the ease of use,” said biomedical engineer Professor Milica Radisic from the University of Toronto who led the project.

“We can build larger tissue structures immediately before they are needed, and disassemble them just as easily. I don’t know of any other technique that gives this ability,” Radisic said.

Two years ago, Radisic and her team invented the Biowire, in which heart cells grew around a silk suture, imitating the way real muscle fibres grow in the heart.

In the new study published in the journal Science Advances, Boyang Zhang, a PhD candidate in Radisic’s lab, described how he used a special polymer called POMaC to create a 2D mesh for the cells to grow around.

It somewhat resembles a honeycomb in shape, except that the holes are not symmetrical, but rather wider in one direction than in another. Critically, this provides a template that causes the cells to line up together.

When stimulated with an electrical current, the heart muscle cells contract together, causing the flexible polymer to bend.

Next the team bonded T-shaped posts on top of the honeycomb. When a second sheet is placed above, these posts act like tiny hooks, poking through the holes of honeycomb and clicking into place.

The concept is the same as the plastic hooks and loops of Velcro, which itself is based on the burrs that plants use to hitch their seeds to passing animals.

The assembled sheets start to function almost immediately.

“As soon as you click them together, they start beating, and when we apply electrical field stimulation, we see that they beat in synchrony,” said Radisic.

The team has created layered tissues up to three sheets thick in a variety of configurations, including tiny checkerboards.

The ultimate goal of the project is to create artificial tissue that could be used to repair damaged hearts. The modular nature of the technology should make it easier to customise the graft to each patient.

“If you had these little building blocks, you could build the tissue right at the surgery time to be whatever size that you require,” said Radisic.

The polymer scaffold is biodegradable; within a few months it will gradually break down and be absorbed by the body.

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