Guinea Pig Hearts Beat With Human Cells
When transplanted into guinea pig hearts, human heart muscle cells (pictured) can beat in time with resident cells.
MEDIMAGE / SPL
Damaged skin and liver can often repair themselves, but the heart rarely heals well and heart disease is the world’s leading cause of death. Research published today raises hopes for cell therapies, showing that heart muscle cells differentiated from human embryonic stem cells can integrate into existing heart muscle.
“What we have done is prove that these cells do what working heart muscles do, which is beat in sync with the rest of the heart,” says Chuck Murry, a cardiovascular biologist at the University of Washington in Seattle, who co-led the research.
It has been difficult to assess cell therapies in animal models because human cells cannot keep up with the heart rates of some small rodents. Cardiomyocytes derived from human embryonic stem (ES) cells typically beat fewer than 150 times a minute. External electrical stimulation can increase that rate, but only up to about 240 beats per minute, says Michael LaFlamme, a cardiovascular biologist at the University of Washington and the other co-leader on the project. Rats and mice have heart rates of around 400 and 600 beats per minute, respectively.
However, guinea pigs have a heart rate of 200-250 beats per minute, near the limit for human cardiomyocytes. After working out ways to suppress guinea pigs’ immune systems so that they would accept human cells, Murry, LaFlamme and their co-workers began transplantation experiments. They also devised a way to make assessing electrical activity straightforward: using recent genetic-engineering technology, they inserted a ‘sensor’ gene into the human ES cells so that cardiomyocytes derived from them would fluoresce when they contracted.