Cardiomyocytes from ESCs: the main thing is the right substrate
Mature cardiomyocytes were grown from human embryonic cells
NanoNewsNet based on the materials of the University of Wisconsin-Madison: Stem cell advance yields mature heart muscle cellsA group of scientists from the University of Wisconsin-Madison obtained from human embryonic stem cells (CESCS) a pure population of mature heart muscle cells – cardiomyocytes.
A substrate with a system of channels of a certain size played a decisive role in this success.
This study, published online in the journal Biomaterials (Salick et al., Micropattern width dependent sarcomere development in human ESC-derived cardiomyocytes), may open the door to significant advances in tissue engineering and in drug development and testing.
Currently, scientists have already learned how to differentiate CESCS into immature heart muscle cells. However, such cells do not develop the necessary internal structures, the so-called sarcomeres, which allow cardiomyocytes to develop contractile force for pumping blood. In addition, in immature cardiomyocytes, the components responsible for establishing contacts between neighboring cells and their coordinated work are less developed.
One of the obstacles in obtaining more mature cells is the substrate for their cultivation: Cescs are known to be fastidious.
"Effectively cultivating stem cells and providing an environment that helps them develop normally and differentiate the way you need is really difficult," says study leader Wendy Crone, professor of engineering physics, biomedical engineering and materials science and engineering at UW–Madison.
Recently, three-dimensional substrates with a microstructured surface have appeared, more accurately imitating the physiological environment surrounding cells. However, most of the previous studies using structuring were conducted on rat cells, says Max Salick, the first author of the paper. "One of the unique aspects of our study is that we can observe the reaction to the geometry of microstructuring of human cardiomyocytes."
The researchers focused on finding a structure, including the right size scale, suitable for human stem cells.
"Our hypothesis is that if we were able to control the shape of cells and how they bind to the environment using this microstructuring, we could direct their development towards the formation of more even, structurally organized fibrous structures more appropriate to the heart," continues Salik.
The new microstructured substrate consists of a series of grooves, or channels. By placing cells in these channels, the researchers saw clear differences in how cells respond to different channel sizes, and the key to success was determining their optimal scale.
"If the channel was too wide, the cells simply did not "feel" their channels and did not align," continues Salik. "But in channels less than 100 microns wide, we really started to see alignment, a clearer sarcomeric structure and a more mature phenotype."
On the left are cardiomyocytes grown under standard cultivation conditions. Sarcomeres are poorly organized, cells are poorly aligned. On the right are cardiomyocytes grown on a microstructured substrate developed by UW-Madison scientists. A clear structure of individual cells is visible, as well as the morphology of the tissue, more corresponding to the physiological one. (Photo: Max Salick)The substrate method is more effective and easily controlled than others already tested by scientists.
And now that it is known that the width of the channels is crucial, they can make them infinitely long, which will allow individual cells to establish contacts and interact with neighboring cells.
"It not only makes them look like sarcomeres, have an internal structure that looks like it should be, and behave as it is supposed to. Such cells establish connections with their neighbors," Professor Crown comments on the results of his work. "From what we have obtained, this is the closest to a pure population of mature cardiomyocytes."
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