Damaged hearts could soon be repaired with an injection of stem cells after British scientists showed vast improvements to tissue.

In Britain there are nearly one million people are living with heart failure, where the heart is too damaged to pump sufficient blood around the body, leading to shortness of breath, weakness and often death.

It can be caused by a heart attack which leaves the heart tissue scarred and unable to pump effectively, high blood pressure or narrowing arteries.

Currently there is no cure, but scientists at the University of Cambridge have found that injecting a cocktail of heart stem cells from different parts of the organ kick starts the repair process.

The researchers used 3D human heart tissue grown in the lab from human stem cells to test the cell combination and found it more than doubled the amount of heart muscles cells that grew and matured, and improved the heart muscle cell’s ability to contract and relax by 2.5 times.

Animal testing also showed it renewed damaged tissue.

Dr Johannes Bargehr, first author of the study at Cambridge, said: “Our research shows the huge potential of stem cells for one day becoming the first therapy for heart failure.