Engineering Living, 3D Human Heart Tissue: Researchers Discover The Right Cellular Mix
By Jenna Tripke
Researchers at the University of Toronto’s Institute of Biomaterials & Biomedical Engineering (IBBME) and the McEwen Centre for Regenerative Medicine have made significant advances in the fight against cardiac disease by defining and formulating, for the first time, the precise type and ratio of cell that produce highly functional cardiac tissue. This study, which was published in the biomedical journal PNAS (Proceedings of the National Academy of Sciences), also marks the first time that scientists have engineered living, three-dimensional human arrhythmic tissue.
“Hearts are not just composed of one type of cell,” Nimalan Thavandira, a fourth-year IBBME PhD student and first author of the PNAS study, explained in a University of Toronto report. With this in mind, his team used pluripotent stem cells mixed with differentiated cells to better understand the composition and cell population of the heart. Through this process, they were able to demonstrate that approximately 25 percent of heart cells are cardiac fibroblasts, while 75 percent are cardiomyocytes.
Using this new knowledge of cellular composition, the researchers were able to create a circular tissue model associated with arrhythmia. The tissue was then defibrillated until the irregularly beating tissue achieved a state of regular contractions. (See the videos below for views of the engineered tissue before and after defibrillation.) The team was also able to miniaturize the arrhythmic tissue into human heart micro-tissues, which could be used to measure both normal and diseased hearts and their response to certain drugs.
Video showing the engineered arrhythmic tissue beating irregularly
Video showing the engineered arrhythmic tissue after it has been effectively defibrillated, returning it to normal function
The results of this study lend credence to bold claims made recently by Stuart Williams, an executive and scientific director of the Cardiovascular Innovation Institute at the University of Louisville. In an interview with Wired, Williams predicted that bioengineers will be able to 3D-print fully functional organs, starting with the heart, within 10 years.
“For bioprinting it is the end of the beginning, as bioprinted structures are now under intense study by biologists,” Williams said. “Dare I say the heart is one of the easiest to bioprint? It’s just a pump with tubes you need to connect. A kidney is much more complex. And then the brain….”