|Posted by BioCoM Executive Account on May 2, 2014 at 11:50 PM|
Scientists from the University of Washington have successfully restored damaged heart muscles in monkeys. These findings suggest that this method is likely to be possible in humans. “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, who led the research.
The approach could be expected to be ready for clinical trials in humans within four years. The experiment involved experimental induced controlled myocardial infarctions, a form of heart attack, in anesthetized pigtail macaques. This was achieved by blocking the coronary artery for 90 minutes. This led to the model for the study of myocardial infarction in primates.
Two weeks into the myocardial infarctions, researchers injected 1 billion heart muscle cells derived from human embryonic stem cells into the monkeys. They were also on immunosuppressive therapy to prevent cell rejection. Over a couple weeks, the stem-cell would infiltrate into the damaged tissue. After maturing within, they assembled into muscle fibers and began to beat in synchrony with the rest of the macaque heart cells. After three months, the cells appeared to be fully integrated.
About 40 percent of damaged heart tissue on average was found to be regenerated. “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,” says Dr. Laflamme, whose team was assigned to generate the replacement heart muscle cells. The researchers also found that arteries and veins from the heart would grow into the new heart tissue. This is the first time that this has been shown to be possible.
However, it is important to note that not all treated animals had improved heart ability to pump blood. There were also worrisome complications where the macaques would have episodes of arrhythmias (irregular heartbeat) weeks after injections. They disappeared after the stem cells matured luckily. The researchers hope to reduce the amount of arrhythmias by using more electrically stable mature stem cells. This will hopefully demonstrate the stem cells are actually strengthening the heart’s pumping power.
James J. H. Chong, Xiulan Yang, Creighton W. Don, Elina Minami, Yen-Wen Liu, Jill J. Weyers, William M. Mahoney, Benjamin Van Biber, Nathan J. Palpant, Jay A. Gantz, James A. Fugate, Veronica Muskheli, G. Michael Gough, Keith W. Vogel, Cliff A. Astley, Charlotte E. Hotchkiss, Audrey Baldessari, Lil Pabon, Hans Reinecke, Edward A. Gill, Veronica Nelson, Hans-Peter Kiem, Michael A. Laflamme, Charles E. Murry. Human embryonic-stem-cell-derived cardiomyocytes regenerate non-human primate hearts. Nature, 2014; DOI:10.1038/nature13233
University of Washington. "Stem cell therapy regenerates heart muscle damaged from heart attacks in primates." ScienceDaily. ScienceDaily, 30 April 2014. .
Categories: Health News