Canadian scientists have developed a way to grow swatches of living heart tissue — containing muscle and "blood vessels" — that beat rhythmically like a real heart.

University of Toronto Prof. Milica Radisic and her team hope to use the technology to grow various kinds of "mini organs" that function the way tissues do inside the human body. That would allow them to be used for drug testing or even for growing replacement tissues to treat people who have suffered a heart attack, for example.

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Scientists have previously grown individual tissues in petri dishes in order to test whether different chemical compounds could potentially function as drugs.

But very few compounds that work in those conditions actually develop into marketable drugs, said Christopher Moraes, an assistant professor of chemical engineering at McGill University in Montreal. "We think this is because all of our discoveries are made in artificial conditions."

Body-like conditions

Moraes was not involved in the new study, but his research, like Radisic's, focuses on how to grow cells in conditions that more closely mimic the human body.

Radisic and her team tried to create a more suitable environment by growing heart cells in a 3D scaffold or "chip" instead of a flat petri dish. The scaffold is made of a stretchy, biodegradable polymer using techniques similar to those used to fashion computer chips.

Boyang Zhang, a PhD student in Radisic's lab, said he was impressed when he first saw heart cells beating rhythmically together on their scaffold in the lab.

Milica Radisic

University of Toronto professor Milica Radisic and her team hope to use their new 'organ-on-a-chip' technology to grow various kinds of 'mini organs' that function the way tissues do inside the human body. (Caz Zyvatkauskas/University of Toronto)

"It's amazing, because you rarely see cells actually move," he said.

Zhang, lead author of the new study, helped improve the scaffold with pores that act as blood vessels and can be used to connect with other cells.

"That is a critical component in our tissues," he told CBC's Christine Birak.

The researchers call the new, improved version AngioChip and described it in a new paper published this week in the journal Nature Materials. It has been tested with both heart and liver tissues.

Implantable tissues

The researchers showed that the engineered heart tissues could be implanted in and connected to the blood vessel network of a living rat.

"This is the first time we see that we can actually connect this directly to the body and actually see the blood flow through," Zheung said.

Moraes said that's an advantage over previous technology.

"Instead of having an organ on a chip, I think they have set us up to have chips in an organ, where we can design most of the environment, put it into an actual living animal or eventually even a person and really study much more complex facets about the biology in a very realistic setting."

Boyang Zhang

Boyang Zhang, lead author of the new study, helped improve the scaffold with pores that a network of blood vessels can grow through and use to connect with other cells. (University of Toronto)

Right now, Zhang said, the researchers are seeing if they can do drug testing on simple versions of AngioChip that contain just a strip of tissue. In the future, the researchers hope to be able to work with more complex versions that connect different tissues from different organs to study how they interact.

And beyond that, they hope to be able to grow tissues outside the human body to treat someone who has had a heart attack, for example.

"We can create artificial heart muscles in the lab and could potentially use it to replace the damaged tissue from the patient."

However, the researchers haven't yet started trying to implant their engineered tissues in humans, and Zhang said he wasn't sure how far away that type of treatment might be.

With files from Melanie Glanz