Scientists have turned skin tissue from heart attack patients into fresh, beating heart cells in a first step towards a new therapy for the condition.
The procedure may eventually help scores of people who survive heart attacks but are severely debilitated by damage to the organ.
By creating new heart cells from a patient's own tissues, doctors avoid the risk of the cells being rejected by the immune system once they are transplanted.Though the cells were not considered safe enough to put back into patients, they appeared healthy in the laboratory and beat in time with other cells when implanted into rats.
"We have shown that it's possible to take skin cells from an elderly patient with advanced heart failure and end up with his own beating cells in a laboratory dish that are healthy and young - the equivalent to the stage his heart cells were in when he was just born," said Lior Gepstein, a cardiologist at Technion-Israel Institute of Technology in Haifa.
The technique was first demonstrated with human cells in 2007, when two teams of scientists, Shinya Yamanaka in Japan, and James Thomson in the US, identified "pluripotency" genes that could wind back the clock for adult cells to a younger stage of development.
In the new study, researchers led by Gepstein took skin cells from two men, aged 51 and 61, who had survived heart attacks, and reprogrammed them into an immature state by infecting them with a virus that carried three pluripotency genes.
The scientists then grew these "induced pluripotent stem cells" into fresh heart muscle, and removed the virus and extra genes used in the procedure.
The cells looked healthy in a Petri dish and crucially, when injected into rat hearts, were woven into the organ and worked alongside the muscle cells already there.
"What was interesting was the cells could integrate with the rat tissue and contract in synchrony. If you put the cells in and they beat with a completely different timing, you wouldn't see any improvement in heart function and may even cause a dangerous arrhythmia," Gepstein told the Guardian.
The technique must overcome major hurdles before doctors can begin clinical trials, but the latest work has boosted confidence that it has potential to help patients. Further experiments to investigate whether the procedure is safe and effective are expected to take up to 10 years, the team said.