Historically, cardiology research has faced inherent limitations because of the simple fact that live, naturally pumping hearts don’t exist outside of the body. A groundbreaking new study recently published by researchers at the University of Minnesota could transform cardiac research and cardiology. The research team announced they have successfully created a 3D bioprinted heart model that pumps naturally, just like a human heart, but doesn’t have to reside in a living body.

3D bioprinting works similarly to 3D manufacture printing, in that it builds three-dimensional structures using a layer-by-layer approach. Instead of resin or plastic ink, a 3D bioprinter uses “bioink,” a liquid made from living cells. The printer layers these inks onto a bio-supportive material; the cells then reproduce into functional, differentiated tissue.

Past researchers have successfully 3D-printed living human heart cells. These efforts used a bioink made from pluripotent stem cells, which can differentiate into any type of human tissue. Researchers genetically programmed the stem cells to grow into heart muscle before printing them onto a cell-supporting biochemical matrix. However, the resulting heart muscle cells couldn’t actually beat together like a real heart, because the printing process couldn’t achieve a functional level of cell density.

To correct this issue, the University of Minnesota team reversed the process used in the past. They created a bioink containing undifferentiated pluripotent stem cells combined with the foundational proteins of the biochemical matrix. After printing the new bioink into a 3D proto-heart shape, the team programmed the stem cells to differentiate into cardiac muscle. Within a month, the team had a centimeter-scale chambered heart model with a cell density level that allowed it to pump exactly like a true heart.

The new study has the potential to advance research in the study of heart function and cardiac disease. The heart model, also known as an organoid, has both cardiac tissue and chambered structuring, providing a close approximation to an actual heart. In the future, scientists could potentially introduce disease into chambered organoids and use them to test cardiac medications or implantable devices. They may also use the process to generate functional heart muscle tissue for life-saving tissue graft procedures.