A groundbreaking stem cell therapy could reverse severe heart failure in 90 per cent of patients in a landmark clinical trial in China, a new study revealed.

Patients with heart failure show signs of shortness of breath, tiredness, swelling in the legs, rapid weight gain, and persistent coughing.

While heart transplants are the main treatment currently to cure the condition, donors are scarce.

Now, researchers at the Nanjing Drum Tower Hospital in China have shown that the stem cell therapy could induce new heart tissue growth and restore function in nine out of 10 heart failure patients, and help slow their cardiac muscle ageing.

In the trial, 10 patients were injected with stem cells that could grow and differentiate into specialised heart muscle cells.

The patients' own body cells were transformed first into unspecialised stem cells called iPSCs, which were then differentiated into heart muscle cells and then injected into the diseased areas of their hearts.

Studies have previously shown that iPSCs can self-renew and can be turned into any type of cell in the body.

As a control group, 10 other patients underwent coronary artery bypass surgery.

All the patients’ heart functions were monitored using cardiac imaging, laboratory tests and cardiac function evaluations.

Nine out of 10 patients injected with the stem cells showed significant heart function in a 12-month follow-up compared to the control group.

Their heart functions were restored to only mild symptoms with normal daily activity.

The patients’ cardiac function was restored to only mild symptoms with normal daily activity, with significant improvement in chest tightness and shortness of breath, researchers said.

They also performed better on a six-minute walking test, almost double the improvement observed in the control group.

“Secondary efficacy analyses indicated that cell transplantation provided significantly greater improvements in 6-min walk distance,” researchers wrote.

Scientists also found that the patients’ hearts, on average, had an improved amount of blood ejected per beat following the stem cell therapy.

In contrast, only 60 per cent of the control group patients reached this level of improvement, with one patient dying eight months after surgery.

No severe adverse events were found in the patients who received the treatment, researchers said.

“Clinically significant tachycardia, which occurred in two patients, peaked at two to three weeks post-procedure and resolved completely,” researchers wrote.

However, future studies are needed to determine the “risk-to-benefit ratio” associated with iPSC heart muscle therapy, scientists said.