In Treatment of Child’s Heart Defect, Doctors Find a Stem-Cell Surprise
By Ron Winslow
Doctors at Yale University have successfully implanted a biodegradable scaffold seeded with a four-year-old girl’s own bone-marrow cells to help treat a serious heart defect, asWSJ’s Heartbeat column describes.
The tube — about three inches long — is made of polyester material similar to that used in the manufacture of dissolvable sutures. Six months after Angela Irizarry’s surgery, it had disappeared, replaced by a bioengineered conduit that acts like a normal blood vessel.
The vanishing act for the scaffold was expected, but what happens to the cells, including stem cells, that spawned the new vessel?
Much to the researchers’ surprise, says Chris Breuer, the Yale pediatric surgeon leading the experimental tissue-engineering project, the cells go away too.
Stem cells and certain other bone-marrow cells have building-block properties that make them the foundation for more specialized cells that grow into the body’s various tissues and structures. Researchers have long believed that stem cells transplanted into heart tissue, for instance, would be a primary component of whatever new tissue that grew as a result.
“A lot of people think that when you put cells in, they turn into whatever cells you want them to turn into,” Breuer tells the Health Blog. “We’ve clearly shown that doesn’t happen in our graft.”
Indeed, in experiments performed to learn how the tubes morphed into blood vessels, Breuer and his colleagues transplanted their scaffold seeded with human cells into mice bred with deficient immune systems to prevent rejection of the cells. Within a few days, the human cells were gone, replaced within the scaffold by mouse cells, including cells characteristic of those that line the inner wall of blood vessels.
Initially, “I refused to believe it,” Breuer says. “I redid the experiment three different ways and saw the same thing every time.”
The upshot: Transplanted cells that have a quality of stem cells don’t build new parts themselves, he says. ”They cause the body to induce regeneration.”
Whether the same process happens in human patients such as Angela isn’t certain, he says. But the finding is consistent with other research that sheds new light on how the power of stem cells may be marshaled to regenerate tissue and body parts affected by birth defects, injury and disease.
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