Backed by the British Heart Foundation, the team has created the substance, which can be injected directly into the beating heart.
The gel works as a scaffold for injected cells to grow new tissue.
In the past, when cells have been injected into the heart to reduce the risk of failure, only 1 per cent have stayed in place and survived.
The new gel is made of amino acids called peptides, which are the building blocks of proteins.
It behaves like a liquid when it is under stress as the peptides disassemble – which is an ideal state to inject it – and then the peptides reassemble, making it solid.
This holds the cells in place as they graft on to the heart.
For the results to be successful, a good blood supply is vital for the injected cells to be able to develop into a new tissue.
To prove that the technology could work, researchers showed that the gel can support growth of normal heart muscle tissue.
When they added into the gel human cells that had been reprogrammed to become heart muscle cells, they were able to grow them in a dish for three weeks and the cells started to spontaneously beat.
Researchers also tested the gel on healthy mice.
They injected a fluorescent tag with the gel into their hearts, and found that the gel stayed on the hearts for two weeks.
Echocardiograms, or heart ultrasounds, and electrocardiograms, which measure the organ's electrical activity, conducted on the mice confirmed the safety of the gel.
To gain more knowledge, researchers plan to test the gel after mice have a heart attack to see if they develop new muscle tissue.
The study has being presented at the British Cardiovascular Society Conference in Manchester.
“We’ve come so far in our ability to treat heart attacks and today more people than ever survive," said Prof James Leiper, associate medical director at the British Heart Foundation.
“However, this also means that more people are surviving with damaged hearts and are at risk of developing heart failure.
“This new injectable technology harnesses the natural properties of peptides to potentially solve one of the problems that has hindered this type of therapy for years.
“If the benefits are replicated in further research and then in patients, these gels could become a significant component of future treatments to repair the damage caused by heart attacks.”
The University of Manchester's Katharine King, who led the research, said the heart had a very limited ability to repair any damage it sustained.
“Our research has been looking for ways to overcome this so we can keep the heart in a healthier place for longer," Dr King said.
“While it’s still early days, the potential this new technology has in helping to repair failing hearts after a heart attack is huge.
“We’re confident that this gel will be an effective option for future cell-based therapies to help the damaged heart to regenerate.”