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Research brief: Researchers 3D print a working heart pump with real human cells:

In the past, researchers have tried to 3D print cardiomyocytes, or heart muscle cells, that were derived from what are called pluripotent human stem cells. Pluripotent stem cells are cells with the potential to develop into any type of cell in the body. Researchers would reprogram these stem cells to heart muscle cells and then use specialized 3D printers to print them within a three-dimensional structure, called an extracellular matrix. The problem was that scientists could never reach critical cell density for the heart muscle cells to actually function.

In this new study, University of Minnesota researchers flipped the process, and it worked.

"At first, we tried 3D printing cardiomyocytes, and we failed, too," said Brenda Ogle, the lead researcher on the study and head of the Department of Biomedical Engineering in the University of Minnesota College of Science and Engineering. "So with our team's expertise in stem cell research and 3D printing, we decided to try a new approach. We optimized the specialized ink made from extracellular matrix proteins, combined the ink with human stem cells and used the ink-plus-cells to 3D print the chambered structure. The stem cells were expanded to high cell densities in the structure first, and then we differentiated them to the heart muscle cells."

What the team found was that for the first time ever they could achieve the goal of high cell density within less than a month to allow the cells to beat together, just like a human heart.

"After years of research, we were ready to give up and then two of my biomedical engineering Ph.D. students, Molly Kupfer and Wei-Han Lin, suggested we try printing the stem cells first," said Ogle, who also serves as director of the University of Minnesota's Stem Cell Institute. "We decided to give it one last try. I couldn't believe it when we looked at the dish in the lab and saw the whole thing contracting spontaneously and synchronously and able to move fluid."

Journal Reference:
In Situ Expansion, Differentiation, and Electromechanical Coupling of Human Cardiac Muscle in a 3D Bioprinted, Chambered Organoid, Circulation Research (DOI: 10.1161/CIRCRESAHA.119.316155)

Original Submission