Researchers from the Universities of Toronto and Montreal in Canada have engineered a major piece of the human heart, and it beats normally.
An ethical, more precise alternative to current methods might be provided by a tiny working model of a human ventricle, which could pave the way for the creation of novel drugs and therapies as well as for the study of the development of cardiovascular conditions.
A millimeter-long (0.04 inches) vessel was reverse-engineered by researchers from the Universities of Toronto and Montreal in Canada. It not only beats realistically but also pumps fluids much like the muscular exit chamber of a human embryo’s heart.
“With our model, we can measure ejection volume – how much fluid gets pushed out each time the ventricle contracts – as well as the pressure of that fluid,” says University of Toronto biomedical engineer, Sargol Okhovatian.
“Both of these were nearly impossible to get with previous models.”
There are often only a few alternatives for studying how a healthy or diseased heart distributes blood.
Without the activity, authenticity is provided by organs that are no longer fully working, such as those that were removed during an autopsy. Although tissue cultures may offer a glimpse into biochemical operation, they fall short of capturing the hydraulics of a three-dimensional, pulsing mass.
Although it’s not always the most ethical choice, using an animal model enables researchers to test how a living heart performs as a pump under the effect of new treatments.
This new organ, which resembles the heart, was developed in a lab using a combination of synthetic and biological materials. It joins a wave of 3D models of human parts that develop and react exactly as nature intended (without unfolding into completely functional organs).
Young rats’ cardiovascular tissues served as the source of the cells, which were subsequently grown on a layer of scaffold printed from a polymer with grooves to guide the growth of the tissue.
The massive final chamber that squeezes blood into the aorta with one powerful stroke was forced to resemble the alignment of heart muscle fibers by this flat mesh.
The team utilized a cone-shaped shaft they called a mandrel to transform the triple-layered stack of heart cells into something that more closely resembles a pulsing chamber. A straightforward ventricle appears after a brief roll in the tissue sample. This tiny tube of cardiac muscle cells just needed a series of small electrical shocks to start beating.
“Until now, there have only been a handful of attempts to create a truly 3D model of a ventricle, as opposed to flat sheets of heart tissue,” says senior author Milica Radisic, a chemist from the University of Toronto.
“Virtually all of those have been made with a single layer of cells. But a real heart has many layers, and the cells in each layer are oriented at different angles. When the heart beats, these layers not only contract, they also twist, a bit like how you twist a towel to wring water out of it. This enables the heart to pump more blood than it otherwise would.”
The vessel’s interior diameter of less than half a millimeter (0.02 inches) and pressure of about 5% of an adult’s heart hardly allow it to eject liquid.
The model is still a fantastic proof of concept and might eventually be expanded to include more tissue layers to depict a more reliable network.
It’s even conceivable that over time the scaffold might be eliminated and a variety of human-derived tissues added, improving the model structure and paving the road for a fully formed, transplantable organ.
“With these models, we can study not only cell function, but tissue function and organ function, all without the need for invasive surgery or animal experimentation,” says Radisic.
“We can also use them to screen large libraries of drug candidate molecules for positive or negative effects.”