Scientists regenerate heart muscle in primates

In a major advance, researchers at the University of Washington have successfully restored damaged heart muscle of monkeys using heart cells created from human embryonic stem cells.

The results of the experiment appear in the April 30 advanced online edition of the journalNature in a paper titled, “Human embryonic-stem cell derived cardiomyocytes regenerate non-human primate hearts.”

See a copy of the paper.

The findings suggest that the approach should be feasible in humans, the researchers said.

“Before this study, it was not known if it is possible to produce sufficient numbers of these cells and successfully use them to remuscularize damaged hearts in a large animal whose heart size and physiology is similar to that of the human heart,” said Dr. Charles Murry, UW professor of pathology, bioengineering and medicine, Division of Cardiology, who led the research team that conducted the experiment.  A physician/scientist, Murry directs the UW Center for Cardiovascular Biology and is a UW Medicine pathologist. He holds the UW Arra and Eva Woods Endowed Professorship.

Murry said he expected the approach will be ready for clinical trials in humans within four years.

In the study, Murry, along with Dr. Michael Laflamme and other colleagues at the UW Institute for Stem Cell & Regenerative Medicine, experimentally induced controlled myocardial infarctions, a form of heart attack, in anesthetized pigtail macaques.

The infarcts were created by blocking the coronary artery of macaque for 90 minutes, an established model for the study of myocardial infarction in primates.

In humans, myocardial infarctions are typically caused by coronary artery disease. The resulting lack of adequate blood flow can damage heart muscle and other tissues by depriving them of oxygen. Because the infarcted heart muscle does not grow back, myocardial infarction leaves the heart less able to pump blood and often leads to heart failure, a leading cause of cardiovascular death.

The goal of stem cell therapy is to replace the damaged tissue with new heart cells and restore the failing heart to normal function.

Two weeks after the experimental myocardial infarctions, the Seattle researchers injected 1 billion heart muscle cells derived from human embryonic stem cells, called human embryonic stem cell-derived cardiomyocytes, into the infarcted muscle. This was ten times more of these types of cells than researchers have ever been able to generate before.

All the monkeys had been put on immunosuppressive therapy to prevent rejection of the transplanted human cells.

The researchers found that over subsequent weeks, the stem-cell derived heart muscle cells infiltrated into the damaged heart tissue, then matured, assembled into muscle fibers and began to beat in synchrony with the macaque heart cells. After three months, the cells appear to have fully integrated into the macaque heart muscle.

On average the transplanted stem cells regenerated 40 percent of the damaged heart tissue, said Laflamme, UW assistant professor of pathology, whose team was principally responsible for generating the replacement heart muscle cells.

The results show we can now produce the number of cells needed for human therapy and get formation of new heart muscle on a scale that is relevant to improving the function of the human heart,” Laflamme said.

Ultrasound studies of the macaques’ hearts showed that the ejection fraction, an indication of the hearts ability to pump blood, improved in some of the treated animals but not all. The researchers also found that arteries and veins from the macaques’ hearts grew into the new heart tissue, the first time it has been shown that blood vessels from a host animal will grow into and nurture a large stem-cell derived graft of this type.

The most concerning complications were episodes of irregular heartbeats, or arrhythmias, that occurred in the weeks after the macaques received the stem cell injections, Murry said. None of the macaques, however, appeared to have symptoms during these episodes, which disappeared after two to three weeks as the stem cells matured and became more electrically stable.

Going forward the UW researchers will work to reduce the risk of arrhythmias, perhaps by using more electrically mature stem cells. They also will try to demonstrate definitively that the stem cells are actually strengthening the heart’s pumping power.

These cells have improved the mechanical function in every other species in which they have been tested, so we are optimistic they will do so in this model as well,” Murry said.

25 thoughts on “Scientists regenerate heart muscle in primates”

  1. Has it being proven to can work without any side effects and causing any harm to human beings. If it can then this shows how closely related we are to monkeys, its just that speciation was well advantageous to us. Te question i’m asking is then are we going to kill the monkeys and remove their hearts to make human with heart problems live………….isn’t that cruel to animals?

  2. I have always been fascinated by stem cell research and all it’s various implications. The ability to grow new tissue and organ will allow for a new peak in modern medical treatment. But this may also give rise to more people who go against doctors and medication, saying that they do not have the right to play god and that with this technology, will be able to create whole human bodies which will also produce the question whether they have souls or not. And could criminals produce new eyes, fingerprints, faces, IDENTITIES.
    Stem cell research has come along way and may be able to help all living organisms, not just humans but i believe much must still be considered with regards to safety management.
    I for one can not wait for they day we will be able to just print out new organs. If that will be possible???

  3. “Wow!”-The first word that comes to mind as read this article.Sounds like something out op a sci-fi film.Whats next? A cure for aging? Even with all this progress concerning stemcell research long term side-effects and consequences are still very uncertain.More research sould definitly be done.Let us also not forget about the few of us against stemcell research for moral reasons.None the less this is revolutionary work which all of us will hopefully benefit from in the future.

  4. i like the fact that technology and science meet. but i agree with most of my fellow bloggers this is truly scary, that one can create new organs and so on from stem cells. only problem i see is that this will only be for the extremely wealthy people and those less fortunate or in dire need for organs will not be able to get them…..

  5. This is very exciting news as this could change the face of cardiology dramatically in the near future if we can only improve it to such a point as to implement it in the treatment of patients with minimal side effects. What would be interesting is to know how long this intervention lasts and how effective it really is in improving a patients situation as well as to how far it can reach in regards to which conditions can be treated with this new procedure.


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