UA device that allows determining the concentration of calcium in heart muscle cells was developed by researchers from the Cardiovascular Research Laboratory of the Center for Biomedical Engineering (CEB) at Unicamp. Calcium transport is essential for the functioning of the heart. The equipment is the second in a line being developed by the team, which is a pioneer in the country, and can be used to measure variations in calcium concentration in other types of cells in which this ion plays a key role in their functions.

Device makes it possible evaluate
the ion in others cells

Calcium, in ionic form (Ca2+), participates in the control of a series of physiological processes in the body, such as cell division, release of neurotransmitters and hormones, secretion, genetic transcription, programmed cell death and even cellular respiration, among others. In the heart, this ion is essential, from the generation and modulation of electrical activity, to triggering the contraction process that allows the pumping of blood into the circulation. Electrical excitation acts as a trigger for contraction, and the increase in intracellular Ca2+ concentration constitutes the link between the two phenomena.

However, it is important that the balance is adequate, as the low concentration of Ca2+ impairs the contractile activity of the heart, while overload can lead to cell death. With each beat, the ion concentration in the cell's cytoplasm increases about 10-fold (which triggers contraction and blood pumping) and then falls to its resting level (which allows the heart muscle to relax and the heart is filled with blood that will be pumped with the next beat).

This variation in cytoplasmic ion concentration is known as a Ca2+ transient. The transient occurs through the action of proteins, which not only transport part of the calcium into and out of cells, but also between intracellular compartments. Thus, the Ca2+ transient controls the contraction cycle, determining both the force developed by the cardiac muscle and the duration of the contraction.

The project - At the Cardiovascular Research Laboratory (LPCv), professors José Wilson Magalhães Bassani, from the Department of Biomedical Engineering at the Faculty of Electrical and Computer Engineering (FEEC), and Rosana Almada Bassani, a researcher at CEB, have developed methods and techniques to study the calcium transport and its relationship with contraction in isolated cardiac cells, as well as designed and developed equipment and devices that allow these measurements. José Wilson Bassini has a degree in Computer Science, a master's degree and a doctorate in Electrical Engineering and has always worked with Biomedical Engineering. Rosana is a biologist, with a master's degree in Biological Sciences and a PhD in Sciences from USP.

Guided by the two professors, master's student Diogo Coutinho Soriano, an electrical engineer from FEEC, developed a simplified microfluorimetry instrument that allows the simultaneous quantification, in isolated cardiac cells, of the time course of calcium concentration and cell shortening (i.e., the cell contraction). To this end, he used a Ca2+ indicator which, once inside the cell and under adequate light excitation, emits light whose intensity is related to the concentration of the ion in the cells.

There are several Ca2+ indicators. Diogo Soriano used Fluo-3, a type of molecule that enters isolated heart cells. These molecules are excited by a light source (LED) and emit light whose intensity is greater the greater the concentration of the ion interacting with the indicator. The difference between the wavelength of the incident light and that of the emitted light allows measurement with low noise and also the quantification of the concentration of Ca2+ ions inside the cells.

“This device is useful for any researcher who needs a tool to measure the calcium transient in any cell in which there is a variation in the intracellular concentration of the ion, and not just cardiac cells”, says Professor Bassani. According to him, the equipment promises to be of great use to students of cellular physiology, since many of them, due to lack of resources, do not focus on the role of calcium and could start doing so. CEB developed the device at a cost around ten times lower than the imported one, when there are no national similar devices. The researcher believes that Brazilian companies can also manufacture it at a reasonable price, although they have not yet detected the market potential.

The equipment - “We assembled a simplified inverted microscope, preserving some of its functional characteristics, and coupled it with a much cheaper light source, using a blue-emitting LED. The chosen lighting and the way the microscope is constructed make the equipment compact and low-priced”, reiterates Bassani. The professor highlights another advantage, not always found in imported equipment. “It is the possibility of simultaneously measuring cell shortening, which can be observed at the same time on a monitor, and without interfering with the Ca2+ measurement. In imported equipment, this simultaneity is only achieved with high-cost accessories”.

The development of the device required master's student Diogo Soriano to learn physicochemical, biophysical and physiological processes. He himself carried out all the experiments with the cells and, using concepts from exact sciences, such as optics, mechanics, electronics and computing, he managed to arrive at a functional and properly tested prototype. The work received support from Fapesp and CNPq, and from a total of 180 studies, it was one of five selected as finalists for the Cândido Pinto de Melo award by the Scientific Committee of the Brazilian Congress of Biomedical Engineering (CBEB), which took place last October at city ​​of São Pedro (SP).

The heart as a target

Several methods created by researchers at CEB's Cardiovascular Research Laboratory are beginning to be applied to understanding serious heart pathologies and, although it is not the focus, also for the development of medicines. “The moment we are faced with the need to solve a problem, we in biomedical engineering, who have already acquired a background related to understanding cellular function, go into the field in search of an instrument that will help solve it. In the case of the equipment developed by Diogo Soriano, our interest was in the process of Ca2+ regulation in the heart. We built a tool to continue and improve research capacity in this area”, explains professor José Wilson Magalhães Bassani.

Results obtained by the LPCv team have been published in important scientific journals, such as the American Journal of Physiology, Biophysical Journal and Journal of Physiology (London). Data published this year by the American Heart Association show that, in 2003, heart disease was responsible for approximately 37% of deaths in the United States, and that it is killing people at an increasingly earlier age. In Bassani's opinion, if these diseases represent a serious public health problem in developed countries, there is no reason to believe that the situation in Brazil is different, since we are also subjected to factors that aggravate and predispose to heart problems, such as stress, sedentary lifestyle, obesity and smoking, not to mention the precarious living conditions of the majority of the population.

This context makes a better understanding of the cardiovascular system and the measurement of normality parameters essential, with the aim of enabling increasingly efficient treatments in clinical practice. José Wilson Bassani states that, through the development of methods to study physiology, it has been possible to develop strategies, medications and procedures that ensure good living conditions for people with heart disease, making them less threatening.