Canadian scientists have “grown” a model of the left ventricle of the human heart. Despite its small size, it is able to efficiently pump the liquid fed to it. This will allow the study of heart cells, its tissues and functions as an organ, the search for new drugs and therapies, the authors of the model hope.
While research into treating cardiovascular disease has made great strides in recent decades, nearly 18 million people worldwide die from heart problems each year. A team of scientists from the University of Toronto and the University of Montreal managed to grow a miniature model of the left ventricle of the human heart, made of living cells.
“With our model, we can measure the volume of fluid ejected, (study) how much is pumped out with each contraction of the ventricle, and the pressure of that fluid,” said Sargol Okhovatian, half-inventor of the model. – Both of these parameters are almost impossible to measure with the help of earlier models – she emphasized.
The left ventricle of the heart pumps oxygen-rich blood to the aorta and then to the rest of the body.
It is difficult to study this on your real heart
There are few options for testing the pumping of blood by a healthy or damaged heart, the researchers explain. Organs collected at the time of autopsy are no longer active. On the other hand, laboratory tissue cultures, although they allow biochemical tests, do not reflect the three-dimensional structure of the organ. There are still animal studies that many consider unethical, and their organs are different from human structures. – Thanks to our model, it is possible to study not only the functions of cells, but also tissues and organs, without invasive surgery or animal experiments. We can also use it to screen large libraries of potential drugs, emphasized Professor Milica Radisic, co-author of the publication, which appeared in the journal Advanced Biology in early July.
What was the research like?
One of the main challenges faced by the researchers was to adequately recreate the correct organ geometry. They explain that culturing cells in a flat layer is not extremely difficult, but getting the shape appropriate for a real organ is a completely different challenge. To deal with it, scientists used biocompatible (non-toxic) polymers from which they made the scaffold. It was structured in such a way as to promote proper cell alignment. Over time, they formed working tissue of the heart muscle. With the help of electrical impulses, their contractions can be stimulated, which is also a kind of training for them.
What is unique about the heart ventricle model
The final model is a triple layer of synchronously contracting cells arranged in a chamber shape with an internal diameter of 0.5 millimeters and a length of about one millimeter. This is roughly the size of a human fetal heart chamber at 19 weeks gestation, the researchers explain. – So far, only a few attempts have been made to obtain a truly three-dimensional model of the ventricle, as opposed to flat cultures of its tissues – noted Prof. Radisic. – Virtually all such models, however, consisted of a single layer of cells. Meanwhile, the real heart has many, and the cells of each layer are arranged at a different angle. When the heart beats, these layers not only contract but also twist. A bit like a towel that is twisted to squeeze the water out of it. Thanks to this, the heart can pump more blood – explains the expert.
Her team was able to recreate this twisting as well, though the researchers point out that a real heart has 11 layers. The model can generate only five percent of the pressure that a real heart creates, but as its creators emphasize, it is normal with the scale used.
“Millions of years passed before such a complex structure as the human heart evolved”
In future research, scientists want to add blood vessels to it, which can increase the number of cell layers and increase the strength of the chamber. They also intend to find a way to remove the synthetic scaffold that a real organ doesn’t have. – Let’s remember that millions of years passed before such a complex structure as the human heart evolved – emphasizes Prof. Radisic. – We will not be able to recreate it in a few years, but in the next steps we can obtain better and better models useful in research conducted around the world – said the expert. Over time, you may even be able to grow hearts that are ready to be implanted in humans. – We are still separated from this for many years, but I feel that such a biosynthetic chamber is an important step in this direction – said Prof. Radisic.
Main photo source: Mohammad Hossein Mohammadi / Sargol Okhovatian