Biohybrid systems, containing both biological and artificial components, provide a unique and effective way to investigate physiological control mechanisms, which could lead to the development of new bio-inspired robotics with a range of medical applications. Designing a biohybrid with the ability to move and function autonomously could be the first step toward the creation of artificial organs that can function similarly to natural ones, such as a pumping artificial heart. Researchers at Harvard University have now designed a biohybrid “fish” consisting of an artificial body and a tail made from human cardiac cells, which can swim autonomously for more than 100 days, providing insights into the feedback mechanisms of muscular pumps in the heart.
The biohybrid fish relies on its tail made from a bilayer of cardiac muscle cells to swim, with the rhythmic contractions of the muscle cells producing the swimming motion. The body and fins of the fish were made from artificial materials such as gelatin and plastic, with the central plastic fin structure enabling the fish to float. The opposite layers of the tail perform reciprocal contracting and stretching motions, creating a closed-loop system that replicates the mechanics allowing the heart to beat and pump blood throughout the body.
The cells incorporated into the biohybrid fish generated autonomous, rhythmic antagonistic muscle movements either optogenetically (light-induced) or self-paced, leveraging the natural mechanoelectrical signaling and automaticity of cardiac cells. The researchers found that their biohybrid outperformed previously biohybrid muscular systems in terms of locomotory speed, and the fish was able to maintain spontaneous activity for 108 days. The team also found that a fish made with just a single layer of cardiac muscle cells showed deteriorated activity within the first month. This study demonstrates the potential use of muscular bilayer systems and mechanoelectrical signaling as a means to promote the maturation of in vitro muscle tissues, the researchers wrote. This work was published in Science.
“Taken together, the technology described here may represent foundational work toward the goal of creating autonomous systems capable of homeostatic regulation and adaptive behavioral control,” the authors concluded.
This research builds on previous work in which cardiac cells from rats were used to create a self-propelling biohybrid ray fish analog. The researchers believe insights from their biohybrid fish will bring them closer to one day building an artificial heart, and also say the fish can provide a platform for studying cardiac diseases like arrhythmia.
Video Credit: Harvard John A. Paulson School of Engineering and Applied Sciences