For the first time, scientists have succeeded in artificially mimicking the ion signalling of heart muscle cells. To succeed, researchers at LiU have used organic electronics based on conductive plastics. The findings, published in Nature Communications, open up for new types of prostheses, heart implants and sensors in the long term.

“There’s a reason why nature has endowed cardiac muscle cells with this particular type of electrical signalling. We do not merely want to mimic the biology, but also to harness the principles that make these signals so effective,” says Simone Fabiano, Professor of Materials Science at Linköping University.

The human heart beats about 2.6 billion times in an average lifetime. This happens continuously, 24 hours a day, throughout life. One of the keys to the untiring work of the heart muscle cells is the transport of potassium, sodium and calcium ions in and out of the cells. The ion transport initiates an electrical impulse called action potential. This in turn causes the muscles of the heart to contract and the blood is pumped forward.

But artificially mimicking this ion transport and action potential has been a challenge, as heart muscle cells differ from other cells in the body. This is because the ion channel that transports calcium works relatively slowly compared to the sodium and potassium channels.

“It’s precisely this slowness that creates a bottleneck if you try to work with traditional electronics that are designed to be fast. In this case, organic electronics are better, because they can transport both ions and electrons and therefore communicate in the same way as the cells in the body,” says Dace Gao, postdoc at the Laboratory of Organic Electronics, LOE, at LiU and lead author of the scientific article published in Nature Communications.

What he and his colleagues at LOE, Campus Norrköping, have done instead is develop an artificial heart muscle cell made of conductive plastic that mimics the electrical function, that is, the action potential, of the cell.

The same research group has previously developed artificial nerve cells that mimic the properties of biological nerve cells. Developing artificial heart muscle cells was a natural next step, as there was no hardware that could imitate the special ion signalling.

According to Simone Fabiano, there are two main reasons for mimicking the electrical dynamics of cardiac muscle cells using organic electronics. One is that researchers can gain a deeper understanding of the material properties required to recreate biology-like signals. The other is that such systems could, in the long term, be used as bioelectronic models and interfaces:

“Since this is hardware, we can in a controlled manner investigate how changes in, for example, ion concentration and pH affect heart-like electrical signals. In the future, we also hope to be able to connect such systems more closely to biological cardiac muscle cells,” says Simone Fabiano.

The researchers envision, for example, how this technology could contribute to small ‘natural’ pacemakers, implants that can activate muscles or sensors that can detect early disturbances in heart function and initiate measures. But this hinges on solving a key issue.

“The artificial cells must be able to receive a signal from a biological cell and then pass the signal on to other cells. The artificial heart muscle cells would then act as a bridge and we will get significantly closer to biomedical applications,” says Dace Gao.

The study was funded mainly by the Knut and Alice Wallenberg Foundation, the Wallenberg Initiative Materials Science for Sustainability, the Swedish Research Council, the European Research Council, the Marie Skłodowska-Curie Actions Postdoctoral Fellowships programme, the Swedish Foundation for Strategic Research, Vinnova and through the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linköping University.