Heart Damage Reversed With Induced Stem Cells
Researchers have found a way to repair damaged heart tissue in mice by reprogramming cells to act like embryonic stem cells, according to a study released Monday that suggests a practical use for the experimental cells.
The new cells, when injected into the mice whose hearts were damaged by a heart attack, actually improved both the structure and function of the heart.
The goal is to eventually be able to use a patient’s own cells to repair their heart rather than replace it with a donated heart, which are in short supply and require dangerous drugs to keep the body from rejecting the foreign organ.
The proof-of-concept study on mice is the first attempt to use induced pluripotent stem (iPS) cells made from ordinary cells to treat heart disease. Many teams are utilizing this new technology to find ways of repairing the body, which is a fast-growing field of research known as regenerative medicine.
The technology was tested by Dr Timothy Nelson and his colleagues of the Mayo Clinic in Rochester, Minnesota, as a way to regenerate heart muscle damaged by a heart attack.
"We’re taking advantage of a diseased tissue environment that is sending out a distress signal that is asking the tissue to repair itself…when we put these iPS cells in, they are able to respond," Nelson said.
Induced pluripotent stem cells are able to form any kind of cell in the body and since they come from adult tissue, their use is less controversial than embryonic stem cells, which come from days-old embryos.
Stem cells offer endless possibilities for regenerative medicine due to their ability to be coaxed into becoming lab-dish replacements for heart, liver, skin, eye, brain, nerve and other cells destroyed by disease, accident, war or normal wear-and-tear. And since the iPS stem cells come from adult tissue, their use is less controversial than embryonic stem cells, which come from days-old embryos.
IPS cells can be made in several ways, but Nelson’s team used a method that uses a virus to transplant genes that turn back the clock on the cells.
According to Nelson, the focus was not on the cell making, but rather on what they could accomplish as far as reversing the damage in heart tissue.
Instead of coaxing the iPS cells into a specific type of heart tissue, they used the iPS cells in their most embryonic-like state.
Just two weeks after the cells had been transplanted, they began making different types of heart tissue, such as heart muscle, blood vessels and the cells that line blood vessels, according to Nelson.
"They were able to respond to this damaged environment and spontaneously give rise to the appropriate tissues and create new tissues within that diseased heart," he said. "That is a key wow factor of this paper."
The cells were transplanted into damaged mouse hearts and within four weeks the team discovered that the cells had actually managed to stop progression of structural damage, restore heart muscle performance lost after the heart attack, and regenerate tissue at the site of the damage.
The structure and the function of their hearts had both improved compared to animals injected with cells that form scar tissue, he said.
There was greater mobility observed in the treated animals, and an ultrasound found significant improvement in the heart’s ability to pump blood.
The findings will hopefully pave the way for human treatments. In theory, IPS cells could be made from a patient’s own skin, allowing people to essentially grow their own transplant without the risk of the body rejecting it as something foreign.
There are no iPS cells currently being used in people because scientists have not quite found a safe way of producing them, though several teams have made significant progress.
Though it might be years in the making, Nelson says technology could very well help people in need of heart transplants.
—
On the Net: