According to the Centers for Disease Control and Prevention (CDC), heart disease is the leading cause of death for men, women, and people of most racial and ethnic groups in the United States. About 647,000 Americans die from heart disease each year, which is roughly one out of every four deaths total in the US.

In order to better study heart disease, Dr. Brenda Ogle and her team at the University of Minnesota have successfully 3D printed a functioning centimeter-scale human heart pump.

Previously, researchers have attempted to 3D print heart muscle cells within a 3D structure called an extracellular matrix. The heart muscle cells were made from induced pluripotent stem cells (iPSCs), a type of stem cell that can turn into virtually any kind of cell. Unfortunately, the cell density needed for the heart cells to function was never reached.

In this study. Dr. Ogle and her team made some slight changes to the process that had failed previously. First, they optimized a specialized ink made from extracellular matrix proteins. They then mixed the newly created ink with human iPSCs and used this new mixture to 3D print the chambered structure. The iPSCS were expanded to high cell densities in the structure first, and then were differentiated into heart muscle cells. The heart muscle model is about 1.5 centimeters long and was specifically designed to fit into the abdominal cavity of a mouse for future studies.

A video of this process can be seen below:

The team of researchers found that for the first time ever they could achieve the goal of high cell density to allow the cells to beat together, just like a human heart. Furthermore, this study shows how heart muscle cells can organize and work together. The iPSCs differentiating into heart muscle cells right next to each other is comparable to how stem cells grow in the body and then undergo specification to heart muscle cells.

A video of the heart pump contractions can be seen below as well:

In a press release from the University of Minnesota, Dr. Ogle elaborates on the implications of this study.

“We now have a model to track and trace what is happening at the cell and molecular level in pump structure that begins to approximate the human heart. We can introduce disease and damage into the model and then study the effects of medicines and other therapeutics.”

The full results of this study were published in Circulation Research.