Cambridge scientists develop mRNA treatment that reactivates heart cells in mice

Scientists at Cambridge University have developed an experimental mRNA treatment that “reawakens” heart muscle cells so they start to divide and help repair damaged muscle, according to a study published in the journal Nature Cardiovascular Research.

In a study in mice, the treatment produced a stronger heartbeat and increased the amount of blood pumped through the heart with each heartbeat by around 10 percent, compared with mice that received a mock treatment, following a heart attack.

The treatment uses mRNA therapy to temporarily activate two proteins inside heart cells, called Myc and Cyclin T1, promoting repair of heart tissue. The therapy was injected into the hearts of the mice after a heart attack, and its effectiveness was assessed using an echocardiogram.

Because the treatment is short-lived and localized, it is not expected to cause any permanent modification to the heart cells, and no adverse effects were seen in the mice. Reassessing the mice after 28 days and after 12 weeks showed that the improvement in heart function is long-lasting.

Study co-senior author Catherine Wilson said: “These are really exciting results.”

She added: “There’s no cure for heart failure, and our treatment could potentially have a meaningful impact on the quality of life of millions of people around the world.”

She also said: “We’re not just treating the symptoms of heart failure — this approach could help the heart to repair itself.”

Around 200,000 people in the U.K. are diagnosed with heart failure each year, and current treatments can reduce symptoms and slow the progression of heart disease but cannot regenerate heart muscle that has already been lost.

After a heart attack, an adult human heart can lose up to one billion heart muscle cells. Unlike many other organs in the body, the adult heart cannot regenerate itself, so lost cells are never replaced.

The team is now working to refine the treatment and has received funding from the British Heart Foundation (BHF) to continue the work. Further trials in larger animal models, and then in humans, are needed to fully establish its safety and effectiveness.

Professor Bryan Williams, chief scientific and medical officer at the BHF, said: “Getting the human heart to repair itself is the holy grail for cardiologists.”

He added: “While the research is in mice, and still at an early stage, it is an important step forward towards therapies which could help repair the damage to the heart following a heart attack.”

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