Tiny beating hearts grown in the lab

Miniature human hearts that beat of their own accord have been grown in the lab.

Scientists from Abertay University in the UK have developed tiny beating hearts to help them find a cure for hypertrophy - a potentially lethal form of heart disease caused by abnormal cell growth. Hypertrophy makes the heart muscles grow so big so fast, they become thick and stiff, making it harder for the heart to pump blood around the body. There are treatments available, but these can only help mitigate the symptoms, they can’t cure the disease once it’s developed.

The tiny hearts have been constructed from stem cells and are just 1 mm in diameter. They contract unaided at around 30 beats per minute. They start out perfectly healthy, so to use them in their research, the team, led by professor of medical biotechnology Nikolai Zhelev, uses chemicals to make them mimic the symptoms of being hypertrophic. Once the tiny hearts are diseased, the team can test a range of newly developed medications on them to see how they work. Some of these medications are entirely new, and have not been tested on humans, so these lab-grown hearts provide a safe testing ground.

"Although human hearts have been grown in labs before, this is the first time it has ever been possible to induce disease in them, said Zhelev in a press release. "Heart hypertrophy can be hereditary, can be caused by diseases such as diabetes, or can be caused by doing too much strenuous exercise. In some people, a life-threatening abnormal heart rhythm will develop, and this is the most common cause of sudden death in young people."

His team used biosensors to label specific molecules inside the tiny hearts and watch what they do. This allowed them to determine which molecules cause the hearts to become hypertrophic so they can develop targetted medications that stop them from going down that path. Some of the medications Zhelev’s team tested had negative effects on the hearts, such as making them beat faster or stopping them from beating at all, but one medication in particular, a new cancer drug, managed to prevent the hearts from becoming hypertrophic.