The researchers dealt with the other big challenge of stem cell death by implanting the cells along with a cocktail of compounds aimed at helping them grow. The cocktail included a growth "matrix"-- a sort of scaffolding for the cells to latch on to as they grow -- and drugs that block processes related to cell death. When using the pro-growth cocktail, the success rate of heart muscle grafts improved drastically: 100 percent of rat hearts showed successful tissue grafts, compared to only 18 percent in grafts without the cocktail.
"The problem of cell death is pretty common in stem-cell treatments," Murry explained. "When we try to regenerate with liquid tissues, like blood or bone marrow, we're pretty good at it, but we haven't been very successful with solid tissues like skeletal muscle, brain tissue, or heart muscle. This is one of the most successful attempts so far using cells to repair solid tissues -- every one of the treated hearts had a well-developed tissue graft."
When the researchers followed up on the stem-cell treatment by taking images of the rat hearts, they found that the grafts helped thicken the walls that normally stretch out after a heart attack and cause the heart to weaken. The thickened walls were also associated with more vigorous contraction.
"We found that the grafts didn't just survive in the rat hearts -- they also helped improve the function of the damaged heart," said Dr. Michael Laflamme, UW assistant professor of pathology and the lead author of the study. "That's very important, because one of the major problems for people suffering a myocardial infarction is that the heart is damaged and doesn't pump blood nearly as well. This sort of treatment could help the heart rebound from an infarction and retain more of its function afterwards."
The next step in studying stem-cell treatments f
|Contact: Justin Reedy|
University of Washington