The heart is still too small to be useful, but this represents an important proof of concept, researchers say.

We’ve all seen how 3D printers can be used to produce a wide variety of materials, but human body parts weren’t exactly on the expectation list — and a heart is probably the last thing you’d expect. But in a new study, researchers from Tell Aviv University have done just that: they’ve 3D printed a miniature version of a human heart, using material from a patient.

“It’s completely biocompatible and matches the patient,” said Tal Dvir, the professor who directed the project.This greatly reduces the chances of rejection inside the body,

Dvir and colleagues harvested fatty tissue from a patient, then separated it into cellular and non-cellular components. The cellular components were then reprogrammed into stem cells and subsequently turned into heart tissue cells. The non-cellular cells were also processed and used as a gel that served as the bio-ink for printing.

The process was lengthy. A massive 3D printer sent a small stream of this bio-ink to print, and the cells were then left to mature for another month. For now, the heart is very small and doesn’t “work” — but this is still an important breakthrough. Previously, only simple tissues had been printed.

A simplified diagram of the heart-printing process. Image credits: Tel Aviv University.

“We need to develop the printed heart further,” Dvir said. “The cells need to form a pumping ability; they can currently contract, but we need them to work together. Our hope is that we will succeed and prove our method’s efficacy and usefulness.”

The potential for this invention is tremendous. Cardiovascular diseases are the number one cause of death in industrialized nations, and heart transplants face a number of hurdles, ranging from the lack of donors to challenging surgery and potential rejection. This would not only ensure that there is always a donor (the patient himself) but also eliminate the risk of rejection.

A human-sized heart might take a whole day to print and would require billions of cells, compared to the millions used to print these mini-hearts, Dvir said. This is still just the very first stage of the project, but it’s still a promising one. Even though it will be a long time before functional hearts can be produced thusly, researchers are also considering printing “patches” to address localized heart problems.

“Perhaps by printing patches we can improve or take out diseased areas in the heart and replace them with something that works,” Dvir concluded.

The study “3D Printing of Personalized Thick and Perfusable Cardiac Patches and Hearts” has been published in Advanced Science.