A new technique enables 3D printing of miniature heart chambers called ventricles that can beat on their own, and may one day help create whole hearts for transplantation.
Miniature-sized heart chambers called ventricles have been 3D-printed with live human heart muscle cells and shown to beat on their own for at least three months.
Artificial heart tissue can be made by growing heart cells in moulds or on scaffolds, but this typically only allows the construction of simple shapes like sheets or rings.
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| A 3D-printed ventricle containing beating heart cells Tilman Esser, University of Erlangen-Nuremberg |
3D printing may allow the creation of more complex structures. In 2019, for example, Nadav Noor at Tel Aviv University in Israel and his colleagues showed they could 3D-print a whole heart; however, it wasn’t able to beat.
Now, Tilman Esser and Felix Engel at the Friedrich-Alexander University of Erlangen-Nürnberg in Germany and their colleagues have developed a 3D printing technique that allowed them to fabricate beating ventricles – the chambers at the bottom of the heart that pump blood to other parts of the body.
They made an “ink” containing live heart muscle cells mixed with collagen protein and hyaluronic acid, which give heart tissue its structure. They used a nozzle to insert this ink into a supportive gel that held it in the desired shape during the printing process, then was melted away to leave the printed structure.
The team showed they could use this technique to print balloon-shaped ventricle-like structures that were 14 millimetres high and 8 millimetres in diameter – about six times smaller than real human ventricles.
The ventricles started to beat a week after they were printed and were still beating after 100 days. Like real hearts, they could be made to beat faster by treating them with a stimulant drug called phenylephrine.
The researchers hope to eventually use the technique to print a whole beating heart with all four chambers, but “there are many challenges in the field that come with scaling up organ models to the size of a native organ,” says Esser.
For example, real-sized hearts require blood vessels to supply sufficient oxygen and nutrients to the muscle tissue. Esser and Engel say their next step will be to add a second printing ink containing vascular cells, which they hope will grow into blood vessels inside the printed heart tissue.
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