As living proof that stem cell therapy can repair damaged heart muscle, Noel Zuniga leapt onto a treadmill for a brisk run and followed with a set of weighted push ups inside the cardiac rehabilitation room at University of Miami Hospital Friday.
Zuniga, 44, did not lose his breath or feel fatigued.
Two years ago, he barely survived what cardiologists call a “widow maker” heart attack, a complete blockage of a major coronary artery. Few expected Zuniga to recover this well without a heart transplant.
But last year, when he could hardly run and felt fatigued just walking in the mall with his wife, Zuniga enrolled in a clinical study at the University of Miami Health System’s Interdisciplinary Stem Cell Institute.
UHealth doctors had saved his life in 2013 — shipping off at a moment’s notice to Panama to implant a special catheter with a pump into his heart, staving off massive organ failure after the heart attack. Now they held out the hope of helping Zuniga’s heart recover much of the function it had lost.
“We got Noel through the worst part, but it left such extensive damage that his outlook for the future was not very bright,” said Robert Hendel, a UHealth cardiologist who cared for Zuniga after the attack.
In short, said Joshua Hare, a physician and director of the UHealth stem cell institute, “He was left with a big scar on the front wall of his heart.’’
Hare said the scar threatened to cause Zuniga’s heart to “remodel” its shape from one resembling a football to one that looks more like a basketball, which then causes congestive heart failure and a condition called sudden cardiac death.
“There's nothing we have available in all of medicine to fix that,’’ he said, “other than a heart transplant.”
In June 2014, as part of the clinical study, UHealth doctors injected human stem cells from a donor’s bone marrow directly into the scar tissue of Zuniga’s heart.
Within about two months, Zuniga said, “I felt a huge difference, and then it just started getting better and better and better, month after month after month.”
On Friday, Zuniga and his wife, Diana, who now live in Virginia with their three children, returned to Miami to thank the UHealth team that saved his life and then helped him regain his old form.
“It’s as if nothing ever happened,” said Zuniga, a Naval Criminal Investigative Service agent who was in charge of the U.S. Embassy in Panama when he suffered the heart attack.
The Zunigas said they want others to hear their story, especially about the power of stem cells to restore damaged tissue. Stem cells — cells with the ability to divide into many different cell types — are influenced by their immediate environment, which determines how they will grow.
Prior clinical studies, including one led by Hare, have demonstrated that stem cell therapy can reduce scar tissue in the heart by 35 to 50 percent, he said, calling it “an enormous achievement.”
The current clinical study, which Hare also is leading, will help determine the ideal dosage of human stem cells needed to repair damaged heart tissue.
Still unknown, however, is whether human stem cell therapy helps patients live longer.
“That study has yet to be done,” Hare said, though he noted that several studies are under way and that he expects they will produce results in two to three years.
Zuniga doesn’t need to wait, however, to know that human stem cell therapy has improved the quality of his life.
He has pushed himself hard in the gym. “I wanted to put these stem cells to the test,’’ he said, “to see if they worked.” And he has high hopes for the future of regenerative medicine.
“I think there will come a time in the future,” he said, “where you will rarely hear of someone getting a heart transplant.”