Stem cells in small hearts fight birth defects
Step to adult repairs
BALTIMORE | The 4-month-old on the operating table has a shocking birth defect, nearly half his heart too small or missing. To save him surgeons will have to reroute how his blood flows, a drastic treatment that doesn’t always work.
So this time they are going a step further. In a bold experiment, doctors injected donated stem cells directly into the healthy side of Josue Salinas Salgado’s little heart, aiming to boost its pumping power as it compensates for what’s missing.
It’s one of the first attempts in the U.S. to test if stem cells that seem to help heart attack survivors repair cardiac muscle might help these tiniest heart patients, too.
“We think the young heart is able to be more responsive,” said Dr. Sunjay Kaushal, chief of pediatric cardiac surgery at the University of Maryland Medical Center, who is leading the study working with University of Miami researchers.
“We’re not saying we’re going to cure it,” Dr. Kaushal said of the birth defect, called hypoplastic left heart syndrome. But “my whole quest is to see if we can make these little kids do better.”
Josue’s parents knew there was no guarantee the experimental injections would make a difference. But their son had been hospitalized since birth and needed open-heart surgery anyway for a chance to go home. Teary-eyed, they clasped hands and prayed over Josue’s crib moments before nurses wheeled him to the operating room.
“We are marching ahead with God,” said Josue’s father, Hidelberto Salinas Ramos, speaking in Spanish through a hospital interpreter.
Nearly 1,000 babies are born with hypoplastic left heart syndrome in the U.S. each year. It’s the most complex cardiac birth defect.
Josue is missing his left ventricle, the main pumping chamber that pushes oxygen-rich blood to the body. Other key structures on his heart’s left side are too small or malformed to work.
Always lethal until a few decades ago, this defect now is treated with three open-heart surgeries performed between birth and age 3. Doctors route blood around the abnormal left heart and they convert the right ventricle — which normally would shuttle oxygen-poor blood to the lungs — into the main pumping chamber.
Today about 65 percent survive at least five years, and many reach adulthood, said Dr. Kristin Burns, a pediatric cardiologist at the National Institutes of Health.
But too many children still die or require a heart transplant because the right ventricle wears out under its increased workload.
That’s why doctors are conducting this earlystage study of whether stem cells help that ventricle work better.
“This is very different than a surgical approach or giving a medicine just to treat the symptoms. This is trying to treat the underlying problem,” said Dr. Burns, of NIH’s National Heart, Lung and Blood Institute.
Even in adults, stem cell regeneration is highly experimental. But small studies involving heart attack survivors and older adults with heart failure have found what Dr. Denis Buxton, a stem cell specialist at NIH’s heart institute, calls a modest benefit in how well their hearts pump blood.
Doctors inject stem cells into the healthy side of a patient’s heart at the University of Maryland Medical Center in Baltimore to compensate for a heart birth defect.