On the one hand, the point of contact between medicine and physics could be in the design and construction of devices that are used in hospitals to treat people, diagnose diseases, carry out analyses, or for other purposes. On the other hand, there are also countless mechanical and otherwise physical processes taking place in every organism.

Broadly speaking, the generally known and recognised laws of physics also apply at the micro level; for example, to the movements taking place inside cells. And by learning more about these processes, scientists can find ways to better diagnose, prevent, or treat the diseases that plague humanity. Biophysics is a science that studies the laws of biological systems and biological processes.

Physicists, chemists, and biologists join forces

Marko Vendelin, Professor and Head of the Laboratory of Systems Biology at the Department of Cybernetics of Tallinn University of Technology (TalTech), is currently investigating how energy is transferred in cardiac muscle cells and the effect this has on mitochondria, the electromechanical connectivity of the heart muscles, and overall cardiac performance. Laboratory mice and rats are used in the experiments. A heart taken from a laboratory mouse can also be used to carry out controlled experiments, to set up different conditions that are needed for scientists to test hypotheses. 

‘Biophysics, which is the area of research of our laboratory, is classified as fundamental science. Our job is not to build specific machines but to use the laws of physics to investigate what is going on in the cell or in the organism in general,’ said Vendelin, describing his work. ‘If we can understand what is going on in a healthy human cell and what changes there when a person is struck by a disease, then we can guide the body towards healing. In real life, this means taking medicine. By studying processes at the cellular level, we can determine which medicines help in treating specific diseases. Biophysicists are looking for so called ‘control points’ that could be influenced to steer the organism towards healing.’

He explains that in a laboratory of systems biology, physicists and biologists work together, which means that both physics and biology experiments have to be carried out and understood. And even though the people working in the lab are either physicists or biologists by profession, they understand very well that they have to deal with both fields and that ultimately, the two fields are intermingled.

Biophysicists have now discovered, for example, how an electrical signal enters a cell through ion channels, how these impulses trigger contraction, and so on. Nowadays, this is already basic knowledge. Marko Vendelin, who started his research career studying photosynthesis, says that as a physicist, he is fascinated by the focus of biology in systems at the cellular level.

He believes that if we want to make broad-based discoveries in science, researchers from different disciplines need to join forces.

Investigating how heart muscle cells work

The direct reason for the research, which involves biologists and physicists alike, is the fact that heart disease is killing millions of people across the globe, and progress in diagnosing and treating it is still slow.

Describing the research on heart muscle, Marko Vendelin says that although experiments on mice are performed as little as possible, there is no good alternative because we do not know how to grow heart muscle cells artificially. This is why we try to get the most out of the experiments we carry out.

‘The cells that make up the heart are cylindrical and elongated, about 100 µm long and 20 µm in diameter,’ described Vendelin. ‘The movement of molecules in this cylinder is slow. The hypothesis of our work is that each cell is made up of particles with dimensions of 1 µm in all directions. In these ‘cubes’, molecules move fast, but they do not move further inside the cell, i.e. they do not leave their cube. We need to first check whether this is really the case and then understand why, in some heart diseases, these small cubes disappear and molecules are able to circulate throughout the cell. The question to be answered is whether or not this is relevant in the case of heart diseases.’

With this insight, we can move on to the question of how this affects the functionality of the heart muscle and how this knowledge can be used to treat heart disease. Scientists are also trying to find a way to prevent heart muscle cells from killing themselves if the blood supply to the heart is disrupted for any reason, i.e. ways to ‘fool’ the heart muscle cells, or change the way they behave.

Understanding the mechanisms to find a cure

Another line of research concerns the ability of the heart to both convert and consume energy. The driving force behind this process is the synthesis of ATP, or cellular respiration, in the mitochondria, which breaks down fatty acids and stores the energy in ATP molecules. For humans, this is most noticeable with physical exertion – the more we exert ourselves, the more our heart swells and the more it pumps blood. It is not entirely clear to scientists how the information that now is the time to make an effort gets relayed to the mitochondria inside the cell.

‘In a nutshell, scientists are trying to understand the workings of a machine they have not built themselves. After all, you can only fix a machine if you know how it works,’ said Marko Vendelin, explaining the aims of cardiac research at the cellular level. ‘This is where physicists, chemists, and biologists come together – all trying to understand how these mechanisms work, determine the control points, and so on. And if we know these things, we can come up with a cure, i.e. fix the machine.’

He admits that there is still a long way to go before there are any tangible or visible results that translate into practice. The first step is not to find a cure, but to understand how one process or another happens and why it happens the way it does. The result of this research could bring us closer to understanding the basics of human physiology.

It should be noted that the same result can be obtained by using a completely different methodology – running controlled experiments to test a hypothesis and seeing what happens. But such an approach undoubtedly requires more experiments on mice and is otherwise more resource-intensive.

‘I would not say one option is better than the other, both are needed and hopefully they will come together somewhere,’ said Vendelin.

The study of the electrical impulses that accompany each heartbeat relates to the research described in that these impulses are transmitted from cell to cell – if one cell is activated, it can pass it on to a neighbouring cell, and so on. It provides a signal that can be measured, for example, to produce an electrocardiogram (ECG) of the heart. Among other things, Marko Vendelin investigates how these impulses work at the single cell level and how this transmission takes place. 

Author: AIN ALVELA (article published in Novaator)