3D heart with chambers, blood vessels printed using the patient's own cells

The researchers took adipose tissue from a patient and then separated it into cellular and non-cellular components. The cells were then "reprogrammed" to become stem cells, which turned into cardiac cells. The non-cellular materials have been turned into a gel that serves as an organic ink for printing, Dvir said.

According to a university press release, only simple tissues – without the blood vessels they need to live and function – had already been printed. The breakthrough was reported in a paper in Advanced Science Monday.

"Patients will no longer need to wait for transplants or take medication to prevent rejection," the press release says.

"Instead, the necessary organs will be printed and fully customized for each patient."

In a room off a laboratory labyrinth, a mbadive 3D printer sent a thin stream of "bio-ink" into a small square container. Inside was a small heart of the size and color of several erasers.

The cells must mature for another month or so, and then they should be able to beat and contract, Dvir said. The printed hearts could be tested on animals, but there is no timetable for testing hearts on humans, he said.

A human-sized heart could take a whole day to print and would require billions of cells, compared to the millions used to print these mini-cores, said Dvir.

It is not obvious that a printer can produce hearts superior to those of humans, he said, adding: "Maybe by printing patches, we can improve or remove sick areas of the heart and replace them with [perfectly]. "