◎ Science and Technology Daily intern reporter Zhang Jiaxin
Harvard University in the United States and Emory University researchers collaborated to use human stem cell-derived cardiomyocytes to create a completely autonomous "artificial fish". This biomix contains both biological and artificial parts and can swim in water for more than 100 days through myocardial contraction. This result helps develop artificial hearts made from living muscle cells and provides a platform for studying heart disease such as arrhythmias. The relevant paper was published in the journal Science on the 10th.
Schematic diagram of an artificial fish swimming autonomously. Credit to Keel Yong Lee, Sung-Jin Park, David G. Matthews, George Lauder, Kevin Kit Parker
The heart has two functional regulatory features: mechanical electrical signaling and automaticity, which the researchers transferred to an artificial zebrafish device. The installation was inspired by the shape and swimming movements of zebrafish. Artificial zebrafish have two layers of muscle cells, one on each side of the caudal fin. The researchers used external light gene stimulation to control its muscle contractions, causing it to swim like a fish. When one side shrinks, the other stretches. This stretch triggers the opening of mechanically sensitive protein channels, which leads to contraction, which in turn triggers stretching, and so on, forming a closed circulatory system that can propel it to swim autonomously for 108 days.
"Through the heart's mechanical electrical signals between the two layers of muscle, we reconstructed a system that automatically circulates with each contraction," the researchers said. "The findings highlight the role of feedback mechanisms in muscle pumps such as the heart.
The researchers also designed an autonomous pacemaker, like a pacemaker, to control the frequency and rhythm of spontaneous contractions. The artificial fish's two layers of muscle and autonomous pace nodes combine to produce a continuous, spontaneous, coordinated swing of the fins.
The first author of the study paper, former postdoctoral fellow in the Biophysics Group of Marine Diseases, said: "Because of the two internal pacing mechanisms, our fish live longer, move faster and swim more efficiently than before. "This innovation provides a model for studying electrical signals in the heart rhythm and for understanding the pathophysiology of sinus node dysfunction and arrhythmias."
图源：Credit to Keel Yong Lee, Sung-Jin Park, David G. Matthews, George Lauder, Kevin Kit Parker
The "physical fitness" of this artificial fish will improve with its "age". Its muscle contraction amplitude, maximum swimming speed, and muscle coordination all increase over the first month as the cardiomyocytes mature. Eventually, artificial zebrafish achieve similar speeds and swimming efficiencies to wild zebrafish.
Senior author Kit Parker, a professor of applied physics at Harvard University, said: "Our ultimate goal is to build an artificial heart that can replace the malformed heart of children. ”
Editor-in-chief dots
The "artificial fish" in this study is made by using heart muscle cells derived from human stem cells, which can be described as one of the results of human stem cell research. What are stem cells? As a kind of multi-potential cells with self-replication and differentiation ability, stem cells can multi-directional differentiation into tissue cells under certain conditions, which is a "specific function" that ordinary cells do not have. Using this trait, stem cells show unparalleled potential in developing artificial organs, treating genetic diseases, and even fighting infectious disease outbreaks.
Source: Science and Technology Daily
Editor: Wang Yu
Review: Yue Liang
Final Judgement: Wang Yu