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(CNN) – After a heart attack, a handful of monkeys recovered some of the pumping capacity that their heart lost after receiving embryonic stem cells According to a study published Monday in Nature Biotechnology. 19659007] Scientists have been trying for years to develop stem cell therapy for heart disease caused by lack of blood circulation, which has contributed to more than 9.4 million deaths worldwide in 2016, according to the report. ;World Health Organization. About the first cause of death in the world [for humans]"said the study's author, Dr. Charles Murray, director of the Institute for Stem Cell Research and the Regenerative Medicine at the University of Washington. "And for the moment, all of our treatments … dance around the root problem, that is, you do not have enough muscle cells."
After inducing heart attacks in macaques, with each beat dropped from about 70%, which is normal, to a 40% lower. One month later, five monkeys receiving human embryonic stem cells recovered 10.6 points on average, compared to only 2.5 in the control group.
Two of the monkeys continued to improve and the others were euthanized a month after receiving stem cells. . They improved an average of 12.4 percentage points over the next two months
. However, some experts say that the value of the new study may exceed these figures, which come from a handful of monkeys. On the contrary, this may have come from the way Murray's team digs deeper into the irregular heartbeats that arose in a subset of these animals after receiving these stem cells
"For several years , everyone is focusing on these arrhythmias, "said John D. Gearhart, a professor at the Perelman School of Medicine at the University of Pennsylvania and at the School of Veterinary Medicine. a former director of the Institute of Regenerative Medicine at the university, did not participate in the new study
"This is a very important observation because now you can perhaps be start designing a strategy to understand what is happening. we prevent that from happening? "Gearhart said." And that's totally, for me, the story of this article. "
Still, the prospect of a 10-point improvement is not insignificant for some doctors. "19659007" This is pretty impressive, "said Dr. Joseph Wu, director of the Stanford Cardiovascular Institute and professor in the departments of medicine and radiology of the medical school. Wu was not involved in the new study.
"Further studies will have to be done to further validate the concept before we move to clinical trials," he said.
Jumping A Beat
Wake up, it's number one in my mind, I eat, I sleep, I drink, I breathe this arrhythmia thing now, "says Murray." We have some very good ideas … but we have not sorted it yet. "
A monkey in the study developed extensive arrhythmias starting 10 days after stem cell injection , for more than 20 hours per day.Another animal was also excluded from MRI analysis for this reason.The study initially recruited 17 monkeys but excluded eight "because of the design of the protocol or the complications … only one of which was related to cell therapy, "wrote the authors.
" It looks like the grafts we put in "The heart runs on electric currents, which means everything you graft. .. you have to get cells electrically coupled to other cells and so beat in unison, "Gearhart says.
This is a problem that Murray said his team needs to resolve before it can achieve its goal of moving to early human testing by 2020. (Three of the study's authors, including Murray, are scientific founders and company that plans to help finance the subsequent phase clinical trials for this research.)
Another challenge is that these monkeys were on immunosuppressive drugs so that they would not do not reject the cells of the human donor. There is also a risk of a tumor, which Murray said he did not observe in heart tests.
Previous studies have shown that human embryonic stem cells improve cardiac function in smaller animals such as mice, rats, and guinea pigs. But it is not clear how the treatment will be for larger animals such as monkeys.
"Many people have cured heart disease in mice, which heal five times a year," he quipped. that a macaque is still much smaller than a human adult, and it is unclear how this treatment could be scaled up in human trials.
"We are always concerned about the species differences between all the organs and tissues we have – and we find them," said Gearhart. "And many times we ignore them at our peril. "
Tiny cells
The new study comes several years after a similar 2014 study by the Murray group suggesting that human embryonic stem cells could regenerate the primates' heart muscle, but that the study does not have the same effect. did not measure how much the heart could pump.
Embryonic stem cells come from day-old embryos and have been the subject of political controversy. strength lies in their ability to differentiate into several types of cells, including "authentic" cardiac muscle cells, says Wu.
This is not the case for adult stem cells, which are present in all louse to be collected from places like bone marrow, fat and the heart itself. These stem cells are thought to work by secreting molecular signals to the surrounding heart, not by turning into cardiac muscle. And they end up dying.
Previous research on the impact of adult stem cells on patients with heart failure suggested that these cells are not harmful to humans – but it is less clear that the health benefits . "Overall, these cells are fairly safe, but at the same time, we do not see a dramatic improvement in heart function," which is often measured in the percentage of blood that a heart pumps with each pressure. 19659007] Despite the lack of definitive evidence that this type of therapy works in humans, consumer direct selling clinics in the United States and abroad offer unproven stem cell therapies. A survey conducted in 2017 at these US clinics that offer stem cell treatments for heart failure revealed that most of those who responded did not need medical records or employed a cardiologist certified by the council. They billed an average of nearly $ 7,700 per treatment using a patient's own stem cells and about $ 6,000 per treatment for donor cells.
The US Food and Drug Administration has repressed these clinics in the past. seek to permanently prohibit two clinics from commercializing stem cell products without regulatory approval. The agency accused them of "significant deviations" from the requirements of good manufacturing practices.
"Personally, I think it's not a good idea to go to these clinics … and [get] injected with these stem cell therapies that have not been proven ", said Wu.
" Progress "
In Murray's study," grafts "of cardiac muscles accounted for an average of 11.6% of the size of damaged tissue by cutting off the size of the tissue. blood supply.
Over time, new cardiac muscle cells of monkeys have developed, vascularized and reduced and improved heart function, the study said.
"The heart has very little ability to grow new cells" by itself, Gearhart said. Previous studies suggest that heart cells multiply at a rate of about 1% per year.
Some doctors remain unsure that the cells in the new study had really remapped the heart in relation to the procedure and impacted the surrounding cells. Human embryonic stem cells have also been studied in the United States for treating spinal cord injury and retinal degeneration, Murray said.
million. Gearhart said the document was "an important contribution". the problem. "But it remains full of hope.
" The heart is one of my loves – do not play with the words, "said Gearhart
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