Advances in science allow scientists to create a kind of fish from human heart cells. In their experiments, these synthetic fish were able to move rapidly in a solution of salt and glucose, using the same force as our heartbeats and rotating rhythmically from side to side.
This nifty miniature circulatory system, developed by scientists at Harvard University and Emory University, can keep swimming to a rhythm for more than 100 days.
The inventors had high hopes for this strange little device, which consists of living heart muscle cells (cardiomyocytes) grown from human stem cells.
Quoted from Science Alert, the creation of these "biohybrid" fish focused on two key regulatory features of our heart: the ability to function spontaneously without the need for conscious input (automaticity), and messages triggered by mechanical movements (mechanical signals).
It is hoped that the insights learned from this study will enable researchers to more closely examine these aspects of heart disease.
"Our ultimate goal is to build an artificial heart to replace a deformed heart in a child," said Kevin Kit Parker, bioengineer at Harvard University.
According to them, while it's easy enough to make something that might look like a heart, making something that actually works like that is a much more difficult challenge.
A fishbot that can wriggle, is a big step towards that. Previously, they created similar "creatures" by harnessing the heart muscle of mice to build a biohybrid pump for jellyfish and cyborg rays.
"I can make a heart model from Play-Doh (toy candle), not that I can create it," explains Parker.
"We could grow a few random tumor cells in a dish until they coagulate into a pulsating blob and call it a cardiac organoid. Neither of those attempts would, by design, recapitulate the physics of a system that beats more than a billion times over your lifetime while simultaneously rebuilding it." the cells quickly. That's the challenge. That's where we work," he explained.
With two layers of cardiomyocytes on each side of the caudal fin, the biohybrid fish were built to be autonomous. He can perpetuate his own movements.
When one side squeezes tightly, the other side stretches, triggering a feedback mechanism that causes the stretched side to contract and then triggers the same mechanism on the other side in a continuous cycle. This system of asynchronous muscle contractions is based on the flight muscles of insects.
Physical bending is a mechanical movement that activates an electrical signal forming ion channels in the muscle. These ion channels trigger muscles to activate and contract.
Exposing the system to streptomycin and gadolinium, which are known to disrupt ion channels in muscles, ultimately lowers swimming speed and breaks the link between mechanical stretching and triggering subsequent contractions on the other. This confirms that ion channels are indeed involved with rhythmic contractions.
"By harnessing the mechano-electrical signals of the heart between the two muscle layers, we recreate a cycle in which each contraction is generated automatically in response to stretching on the opposite side. "The results highlight the role of feedback mechanisms in pumping muscles such as the heart," says the bioengineer. Harvard University Keel Yong Lee.
Parker and colleagues also integrated systems such as pacemakers into the biohybrid: a group of isolated cells that control the frequency and coordination of these movements.
"Due to two internal pacing mechanisms, our fish can live longer, move faster, and swim more efficiently than previous 'creatures'," explains biophysicist researcher Sung-Jin Park, one of the study's authors.
The tissue-wide contraction of the biohybrid fish is comparable to that of the zebrafish modeled by the biohybrid, more efficiently pushing small devices around than mechanical robotic systems.
"Instead of using cardiac imaging as a blueprint, we identified the key biophysical principles that make the heart work, used them as design criteria, and replicated them in a system, living and swimming fish, where it was much easier to see if we were successful or not." , said Parker.