Nav: Home

Luminous heart cells: Jellyfish proteins assist in heart rhythm disorder research

September 02, 2016

Cell models from stem cells serve an ever-increasing role in research of cardiac dysfunction. Researchers at the Technical University of Munich (TUM) have succeeded in producing cells which offer new insights into properties of the heart. They installed a molecular sensor into the cells which emits light, and not only makes the cells' electrical activity visible, but also makes it possible for the first time to quickly identify cell types.

It has been possible to produce so-called induced pluripotent stem cells in the laboratory for the past ten years. These stem cells are derived from white blood cells, for example, and can be infinitely reproduced in the laboratory, and be turned into all possible types of cells. This has enabled the use of heart cells produced in this way in order to investigate cardiac rhythm dysfunctions, for example. Animal experiments are only of limited use for this application, and tissue samples cannot be easily taken from patients' hearts. Cultivated heart cells, however, provide the opportunity to research such diseases in a 'miniature' format.

"Our development solves several problems which had made working with such cell models difficult," said t Dr. Daniel Sinnecker, Cardiologist at TUM's Klinikum rechts der Isar. Laboratory-produced heart cells still pose the problem of how one can best measure electrical activity. In the past, microelectrodes were most commonly used in order to directly determine the cells' electrical signals. This procedure, however, is quite tedious, and can only be used on a small number of cells.

Differences between cell types

In addition, not all heart cells are alike. All heart cells are able to contract at their own cyclic rhythm, and to forward electrical signals to neighbouring cells. On the other hand, the cells which form the various structures of the heart, such as the atria, the chambers or the sinus node, i.e. the 'pacemaker' of the heart, differ significantly from each other, for example in their action potentials. These are variations in electrical voltage between the inside and outside of cells which form an electric signal that controls the excitation process in the heart and thus its contractions.

This difference becomes relevant when examining rhythm disorders which are caused by malfunctions in specific areas of the heart muscle. Producing heart cells from stem cells, scientists today have only insufficient ways of influencing whether those cells become heart chamber cells, atrial cells or nodal cells. In order to investigatea particular disorder, scientists must meticulously identify the type of each individual cell.

Biological sensors instead of microelectrodes

Daniel Sinnecker and his team described a possible solution for both of these problems in their article in European Heart Journal. Instead of attaching microelectrodes to cells, the scientists used biological sensors. These are built from fluorescent, i.e.luminous, protein from deep sea jellyfish. The DNA which contains the "construction plans" for these sensor proteins is inserted into heart cells, which then produce the sensor proteins. When the altered heart cells are stimulated with light at a specific wavelength, they produce light at a different wavelength. The precise color of the returned light depends on the voltage difference between the cells' interiors and exteriors. One can therefore measure and record the action potential of individual cells using a special camera.

A special characteristic of this new method is that the inserted DNA can be coupled with specific recognition sequences, so-called promoters. These ensure that the sensor proteins are produced only in specific types of heart muscle cells. Thus, it becomes possible to capture only the electrical signals from atrial cells, heart chamber cells or sinus node cells, as needed.

New possibilities for investigating drugs

In contrast to the prior cumbersome microelectrode technique, this method offers significantly improved performance. "We can already investigate hundreds of cells in one day instead of only a handful," says Zhfen Chen, first author of the study. "This process can basically be automated and scaled up, so that thousands of cells can be investigated at the same time."

"In the future, we can use our method not only in the laboratory in order to study disease," says Daniel Sinnecker. "The fact that we can investigate large numbers of cells means that we can also use this method for investigation of drugs, in which, for example, we can investigate whether a product has a negative effect on heart muscle." A challenge for such new types of procedures is that the cells must be produced in the needed quantities. Daniel Sinnecker and his team are working on increasing the sensitivity of their method.
-end-
Original publication

Z. Chen, W. Xian, M. Bellin, T. Dorn, Q. Tian, A. Goedel, L. Dreizehnter, C. M. Schneider, D. Ward-van Oostwaard, J. King Man Ng, R. Hinkel, L. S. Pane, C. L. Mummery, P. Lipp, A. Moretti, K.-L. Laugwitz, D. Sinnecker. "Subtype-specific promoter-driven action potential imaging for precise disease modelling and drug testing in hiPSC-derived cardiomyocytes". Eur Heart J (2016). DOI: http://dx.doi.org/10.1093/eurheartj/ehw189

Technical University of Munich (TUM)

Related Stem Cells Articles:

First events in stem cells becoming specialized cells needed for organ development
Cell biologists at the University of Toronto shed light on the very first step stem cells go through to turn into the specialized cells that make up organs.
Surprising research result: All immature cells can develop into stem cells
New sensational study conducted at the University of Copenhagen disproves traditional knowledge of stem cell development.
The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.
Healthy blood stem cells have as many DNA mutations as leukemic cells
Researchers from the Princess Máxima Center for Pediatric Oncology have shown that the number of mutations in healthy and leukemic blood stem cells does not differ.
New method grows brain cells from stem cells quickly and efficiently
Researchers at Lund University in Sweden have developed a faster method to generate functional brain cells, called astrocytes, from embryonic stem cells.
More Stem Cells News and Stem Cells Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...