Scientists use stem cells to grow a beating human heart muscle for the first time ever

Scientists have grown the first human heart muscle that functions just like an adult's would.

Instead of the nine months it takes for a baby's heart to develop in the womb, they grew a functioning heart from stem cells in just four weeks.

Although researchers can grow many tissues, including the heart muscle, from stem cells, scientists at Columbia University were able to build one mature enough to be useful for medical research for the first time, the Daily Mail reports.

This development is a step forward in studying human physiology as it gives researchers a way to test treatments for conditions like heart failure on a lab-grown heart that can mimic a diseased adult one. 

This isn't the first time scientists have managed to grow a heart muscle, but senior author Dr Gordana Vunjak-Novakovic said those cardiac tissues have failed to mimic or show some of the critical hallmarks of an adult human heart, like it's tissue structure and beat pattern.

“Many of the ongoing efforts including those from our lab have been biomimetic in nature, trying to recapitulate the known events present during native development,” said Dr Vunjak-Novakovic, professor of medicine at Columbia University Vagelos College of Physicians and Surgeons. 

“The common approach in our field has been that the more mature the starting cardiomyocytes, the better,” said her fellow researcher Dr Kacey Ronaldson-Bouchard. 

“Because these efforts have been limited in how much maturation can be achieved, we decided to try something totally new: to explore the concept of accelerated development,” she added.

The conventional wisdom for growing stem cell-based organs is to use cells in a later stage of development so that they are closer to specializing into the kind of tissue the scientists wish to study. 

But in growing their new heart, the Columbia researchers tried a different and bold method. 

In other words, they used very early-stage stem cells, which were easier to manipulate and, they hoped, would respond better to stimulation
intended to accelerate their growth.  

To speed up the development of the heart tissues, the researchers delivered electric pulses to the heart to stimulate it enough to make it twitch, which is exactly what happens in healthy heart muscle in the body.

“We found that very early-stage cells, which still have developmental plasticity, would respond better to the external signals we deliver to drive maturation,” said Dr Ronaldson-Bouchard.

Scientists were also able to develop the methods and software to measure the frequency, amplitude, force of contractions, and its responses to drugs.

This breakthrough also enables them to manipulate the cardiac tissue to make it behave like a diseased heart so that they can further research life-threatening conditions impacting the organ as well as its response to certain drugs.