Scientists at the University of Toronto’s Institute of Biomedical Engineering discovered a way to grow heart cells in a lab that act like adult human heart tissue. Usually, lab-grown heart cells act more like newborns, which makes them less useful for medical testing. Scientists usually try to fix this by testing one or two nutrients at a time. However, that process is slow and misses how different biological signals work together.

To solve this, researchers used a computer algorithm to test many combinations of nutrients and hormones at once. They looked at 169 different mixtures to find the best one. This led to a new culture medium called C16. Heart cells grown in C16 have better structure, energy use, and electrical activity.

“The stem cell community has managed incredible advances in producing the many types of differentiated cells that allow the development of a functional heart, but the mechanisms that lead to the maturation of this tissue are still unclear,” said Dr. Neal Callaghan, the lead and co-corresponding author of this research. “It’s a bit like having one half of a very detailed road map.”

“This ultimately limits the use of engineered heart tissue in drug testing or in surgical grafting,” said Callaghan. “Our goal was to produce a general-purpose formulation that anyone can use in their own application of stem cell-derived heart tissue.”

The Path to Better Heart Testing and Treatment

Finding out if a new drug is safe can take a long time and cost a lot of money. Sometimes, a drug fails in clinical trials because it harms the heart, a problem known as cardiotoxicity, and animal testing does not always catch this.

“One of the most common reasons that a promising new medication doesn’t make it to patients is that it shows signs of cardiotoxicity in clinical trials,” said Callaghan.

“Animal models often aren’t very reliable in predicting this cardiotoxicity, and as a result it is slower and more expensive to produce effective drugs,” Callaghan added. “Ultimately, patients are left waiting. We hope that these new methods can help to improve our predictions of cardiotoxicity in pharmaceutical testing.”

By using C16 on miniature 3D heart tissues, the team created a platform that beats more forcefully and acts much like a real heart.

The team has already licensed the medium to Axol Bioscience, where it is sold as MyoMax. Additionally, they started a company called boutIQ Solutions to keep improving the recipe.

“Working with boutIQ solutions, our next step is to create even better media formulations to grow mature heart muscle cells that can be used to repair damage caused by a heart attack,” said Professor Craig Simmons, co-corresponding author of the study.