Heart Stem Cells From Human Embryo ‘Hot Spot’ May Fix Damage
bloomberg.com
By John Lauerman
[Excerpt: “It suggests a new way of looking at heart disease as a stem cell disease,” he said. Comments?]
July 1 (Bloomberg) -- Stem cells found in the forming hearts of human embryos may help doctors repair damaged organs and understand life-threatening birth defects, Harvard University scientists said.
The stem cells, called Isl1, which appear three weeks into an embryo’s development, can become any of the three major types of heart tissue, researchers led by Kenneth Chien, director of the cardiovascular disease program at the Harvard Stem Cell Institute said today in the journal Nature. The cells are found in a “hot spot” where heart birth defects occur, suggesting they may play a pivotal role in these conditions, he said.
Doctors have conducted numerous studies, with mixed results, using so-called “adult” stem cells that come from mature tissue to repair damaged hearts. While adult cell transplants haven’t generated new muscle to bolster the heart’s pumping, embryonic cells may be better suited to this treatment, said Jeanne Loring, director of the Scripps Research Institute Center for Regenerative Medicine in La Jolla, California.
“This is a recipe for all the other cell therapy applications we’re looking for in the pancreas, the liver, and the brain,” said Loring, who wasn’t involved in the study, in a telephone interview. “Finding the right cell type is the first step to knowing how to treat degenerative disease.”
Heart disease is the leading cause of death in the U.S., according to the Centers for Disease Control and Prevention in Atlanta. The organ weakens when oxygen-bearing blood vessels choke off in a heart attack, which kills muscle tissue, or the heart becomes enlarged and flabby, as occurs in heart failure.
Company Endeavors
Geron Corp. and Advanced Cell Technology Inc. are developing ways of using embryonic stem cells to treat diabetes and other diseases caused by the death of specialized tissues. StemCells Inc., Osiris Therapeutics Inc., and other companies focus on therapies using adult stem cells which, tucked into the mature tissues that they repair, are generally more plentiful.
Finding cells to replace damaged heart tissue has been difficult. Chien originally identified Isl1 cells in mice and human newborns in 2005, when he was a researcher at the University of California, San Diego. Since then he has performed a painstaking process of describing the cell’s identifying characteristics, and tracing it back through human development to the earliest stages of the embryo.
After the fusing of a sperm and egg cell, the formation of the human body begins with the growth of an embryo containing powerful stem cells that can produce any human cell type. As the embryo grows, its stem cells divide into cells that have more specific jobs.
Early Heart Formation
Isl1 cells begin appearing just as the body’s organs begin forming, at about three weeks into development, said Chien, who also is a cardiologist at Massachusetts General Hospital in Boston.
The cells were first found where part of the fetal heart pumps blood into the aorta, an area often afflicted by deformities in Down syndrome and other genetic diseases, Chien said. Genes involved in those heart abnormalities also are active in Isl1 cells, he said.
“It suggests a new way of looking at heart disease as a stem cell disease,” he said.
About 1.3 percent of babies are born in the U.S. each year with heart defects, said Siobhan Dolan, a consultant to the March of Dimes nonprofit group that promotes infant health. Heart defects can arise on their own or as part of broader conditions such as Down syndrome, said Dolan, who is also an obstetrician/gynecologist at Montefiore Medical Center in New York.
Fetal Heart Repair
Chien’s lab will begin experimenting with how to stimulate and grow embryonic stem cells to become Isl1 cells that can make the muscle and blood vessel cells of the heart, Chien said. Such cells may be useful to repair hearts of fetuses that are known to have genetic disorders, he said.
“One could envision the possibility of using stem cell therapy and regenerative medicine in fetal states, because these are debilitating and life-threatening diseases,” he said.
Scientists also will investigate whether Isl1 cells can be made by stimulating cells from skin and other tissues to gain embryo-like power, said Scripps’s Loring. The research offers promise for babies with heart defects in the years to come, said Dolan.
“This is one more step that gives us hope of making a difference for children with cardiovascular malformations,” she said.
To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.
Last Updated: July 1, 2009 13:00 EDT |
