Scientists have taken a step towards a radical new treatment for heart attacks with a stem cell therapy that can partially repair damage to the organ.
The treatment uses heart cells which are created in the lab from the skin of a donor who is chosen to be a good genetic match for the recipient.
Tests in monkeys showed that injections of freshly-made heart cells were quickly incorporated into damaged areas of the heart and helped the organ to pump more vigorously.
But monkeys that had the procedure also developed unusual heart rhythms, leading the researchers to concede that far more work is needed before the treatment can be considered safe enough for human trials.
Heart attacks are one of the leading causes of death in the developed world. In the UK alone, hospitals deal with nearly 200,000 cases each year. While 70% of patients survive, many are left with tissue damage that stops their hearts from working properly.
One idea scientists have had to treat heart attack survivors is to take skin cells from the patient and convert them into pumping heart cells. The hope is that, when injected into the heart, these cells take hold and help the heart pump more effectively. The advantage is that the heart cells will not be rejected by the immune system, but the procedure is time consuming and expensive to do for individual patients.
In the latest work, researchers in Japan took a different tack. They induced heart attacks in five macaques and then treated the damage with heart cells created from the skin of a donor monkey. The donor was selected to be a close genetic match, but the recipients still need drugs to stop their bodies rejecting the cells.
Yuji Shiba and others at Shinshu University injected the monkeys with 400m lab-made heart cells and found that they replaced about 16% of the damaged tissue. The new cells were wired up with healthy ones in the heart and over 12 weeks started to help the organ to pump more strongly. Tests revealed, however, that all of the monkeys developed unusual heart rhythms after the therapy. Details appear in the journal Nature.
The scientists are now trying to understand the precise cause of the abnormal heart rhythms, but Shiba told the Guardian: “I think we can manage the post-transplant arrhythmia.”
Sam Boateng, who studies the mechanisms of heart failure at Reading University, said the work was exciting because it was a step towards the possibility of repairing a damaged heart following a heart attack.
“Currently, the only long term option for these patients is heart transplantation, but there are not enough donors to meet the current demand,” he said.
But he added that many challenges remain. “Ideally, immune rejection would be eliminated if the cells could be derived from the same patient, but this is costly and time consuming at a time when the patient requires immediate treatment. Another concern is that the incomplete integration of the transplanted cells could result in irregular heart beats which can be deadly,” he said.
Sian Harding, director of the British Heart Foundation cardiovascular regenerative medicine centre at Imperial College London, said the Japanese team’s work was a significant step forward. “They strengthen the case that a bank of pre-prepared matched [cells] could be used to treat patients, without relying on the long process of reprogramming and differentiating the patient’s own cells.”
“The arrhythmias were seen in a previous similar study, but in neither study did they prove fatal and both suggested that they would decrease with time. Clinical strategies for preventing sudden cardiac death from arrhythmia, such as implantable cardiodefibrillators, may therefore be necessary as adjunct therapy for some months after implantation,” she added.
make preferable
