Their findings were published on 15 April in a study in Advanced Science.
"It's completely biocompatible and matches the patient", reducing the chances of rejection inside the body, said Tal Dvir, the professor who directed the project.
Until now, the university said, scientists have been successful in printing only simple tissue without blood vessels.
Heart disease is the leading cause of death in the U.S. and Israel, and heart transplants are often only afforded to those with end-stage heart failure, but the lengthy wait (up to six months) for a suitable donor can often prove fatal.
The current state of the primitive heart can be compared to the heart of an embryo. Given the dire shortage of heart donors, the need to develop new approaches to regenerate the diseased heart is urgent.
But it's the first to be printed with all blood vessels, ventricles and chambers, using an ink made from the patient's own biological materials.
Until now, 3D printing has only been used to produce simple tissues without blood vessels, including making the structure of a heart but without the necessary vascular elements to make it actually pump.
The heart the Tel Aviv University team printed in about three hours is too small for humans - about 2.5 centimetres, or the size of a rabbit's heart.
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Research for the study was conducted jointly by Prof Dvir, Dr Assaf Shapira of TAU's Faculty of Life Sciences and Nadav Moor, a doctoral student in Prof Dvir's lab. Inside sat a small heart the size and colour of several pencil erasers.
The 3D-printing technology is already being used to construct entire houses in just 24 hours, but using the tech to create a human heart was proving hard.
For the research, a biopsy of fatty tissue was taken from patients, according to a release.
Cells from a patient's omentum tissue are separated and processed into a personalized thermoresponsive hydrogel.
The differentiated cells were then mixed with the bio-inks and were used to 3D-print patient-specific, immune-compatible cardiac patches with blood vessels and, subsequently, an entire heart. "In our process, these materials serve as the bio-inks, substances made of sugars and proteins that can be used for 3-D printing of complex tissue models", Dvir said.
"The biocompatibility of engineered materials [was] crucial to eliminate the risks of implant rejection, which jeopardizes the success of such treatments", said Dr. Dvir.
"Ideally, the biomaterial should possess the same biochemical, mechanical and topographical properties of the patient's own tissues", Dvir noted.
The next step, they said, is to teach the hearts to organize and interact with each other and achieve pumping ability. The printed hearts could be tested on animals but there's no timetable for testing hearts on humans, he said. Currently, the cells can contract but do not work together.