Utah, USA

How is this possible that some fish and amphibians can clear cardiac scar tissue and regrow damaged muscle as adults whereas the same seems impossible in humans? It is understood that physiological differences between fish and mammals make such comparisons irrelevant, so scientists started off by comparing two fish species: zebrafish, which can regenerate its heart, and medaka, which cannot. Jamie Gagnon led a team of biologists at University of Utah and conducted this study to find the possible answers to this question.

Advertisment

“We thought by comparing these two fish that have similar heart morphology and live in similar habitats, we could have a better chance of actually finding what the main differences are,” said Clayton Carey, a postdoctoral researcher in the Gagnon lab.

The study was unable to solve this mystery but revealed valuable insights into the myriad factors at play.

Also read: NASA to launch drone-like Dragonfly rotorcraft to explore Saturn`s moon Titan

Advertisment

“It told us these two hearts that look very similar are actually very different,” Gagnon said.

How was the study conducted?

At the Gagnon lab, scientists first injured the fish’s hearts using devices, resembling heart attacks in humans.

Advertisment

Then, scientists extracted their hearts after certain time frames to know how the fish have responded to the injury over different periods of time.

“Zebrafish have this immune response that is typical of what you might see during a viral infection, called an interferon response,” Carey said. “That response is completely absent in medaka.”

Also read: Devil Comet makes spectacular return after 7 decades, graces Australian skies

The study also found that medaka doesn’t have a certain type of muscle cells that are present in zebrafish.

“My hunch is the ancestor of all animals could regenerate its heart after an injury, and then that’s been repeatedly lost in different types of animals,” Gagnon said. “I would like to understand why. Why would you lose this great feature that allows you to regenerate your heart after an injury?”

Scientists concluded that zebrafish’s capacity to regenerate is linked to its immune system, but understanding exactly how would take more research.

(With inputs from agencies)