The concept of printing up organs, which until very recently was something you would expect to see only in a science fiction movie, is a product of two parallel scientific breakthroughs: One is the world of 3-D printers which became a reality about a decade ago initially as an engineering wonder and ore recently as applied science with many technological applications and economically accessible.

The second area in accelerated development in recent years is that of molecular biology and genetic engineering which allows researchers to map out and intervene in basic biological processes – at the cellular and nuclear DNA levels.

The model of the printed human heart presented by researchers at Tel Aviv University has raised a lot of interest worldwide. It’s all about a meeting point between two axes of development. A proof of probability that dispels more than a few doubts with regard to the future possibility of printing human organs. It has to be said more than once to believe it: Researchers have created a human heart from human cells (and we can also be proud of the fact that these researchers came from Israel).

Israeli scientists print world's first 3-D heart Credit: Haaretz

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In many respects this is the start of a new chapter and there’s a this is just the beginning with more than a few obstacles to cross before we start coming across people transplanted with printed organs, made of their own cells. But it’s also a lesson with regard to the unexpected way in which scientific developments can sometimes happen. Prof. Tal Dvir, who led the research, said there is still a long way to go but the achievement creates a new horizon. The beginning of a path in which it’s clear to the researchers what must happen to in order to turn the vision into actually being able to give people functional 3-D printed organs.

The photographs of the printing process are amazing. But what’s the status of this sort of heart transplant and how close are we to seeing it happen?

In the printing stage, the hearts are placed inside a bioreactor, a sort of container filled with nutrients for cells (a cultivation medium) and which is capable of monitoring and creating an optimal environment intended to encourage the process of “maturing” the hearts so that they create unified, beating tissue. “It’s going to be a process of trial and error. We want to see whether all the pieces fit together to carry out cardiac activity properly for pumping. We don’t expect to see it succeed immediately. But it will happen,” Dvir said.

Open gallery view A researcher from Tel Aviv University holds the world's first 3-D printed heart, April 15, 2019 Credit: Tomer Applebaum

What’s the next stage after the hearts mature and start to operate sufficiently? Researchers hope to transplant the first printed heart in animals like rabbits and rats within a year, but what about human beings?

Researchers find it hard to commit to any schedule just yet. In general their aspiration is for hospitals to have the right printers to generate three— dimensional human tissue or complete organs as complex as the heart within a decade.

How significant is the current achievement in the realm of printing human organs?

“Very significant. The link between the world of 3-D printing and biology and to printing human organs is relatively new. In this context the use of printers to create replacements for bone such as titanium thigh bones or tissue from natural materials or half natural such as marrow, which is a “passive” tissue or an artery that carries the blood. This is the first time any real organ has been printed, with all that it means one that requires a broad set of biological characteristics.”

What are the limitations of this new kind of heart?

“It’s still not perfect and its ability to function hasn’t been proven yet. The fact [that] it comprises two types of cells, muscle and blood, is a significant advancement but heart cells come from some other subsets of cells as well. Researchers have the technological capability to create these cells and create other engineered cells from stem cells, as they did to produce these cells, and that’s what they plan on doing going forward.”

Open gallery view 3-D-printed heart engineered by Tel Aviv University scientists. Credit: Tomer Applebaum

What are the limitations of printing a human heart in natural size ready for transplant?

Dvir said “there are a few limitations with regard to various parts of the process, which are constantly advancing: Firstly the number of cells needed to create a normal size human heart is tremendous. It takes billions of cells and there’s the science that deals with replicating billions of cells. And here we come to the role of accelerating the cell growth culture. Secondly, the printers. The level of the printers is currently good but they are still not in sufficient resolution. This is also an area that will continue to develop.

The moment such infrastructure exists they will be able to produce all types of relevant cells and the print a heart true to reality. “

Will it be possible to create a stronger, “upgraded” heart someday?

Dvir: “At the moment we’re focusing on creating a printed heart that will replicate a real heart as closely as possible.”

What does this mean with regard to printing other human organs?

“On the one hand the ability to print a heart is a kind of proof of a basic ability to link up two worlds. On a more particularistic level, because every organ has its characteristics. I’m not sure the progress toward printing a heart will necessarily lead to printing such organs as a kidney, a liver or a pancreas.”

What other applications does this technology have?

“The creation of printed tissue will apparently come into greater use in the coming years and could change the face of medicine and replace the healing of various organs from the heart to severe burns. A patch of heart tissue that researchers developed in parallel has been tried thus far in pigs.”