Today, 2 1/2 year-old Avery Gagnon looks perfectly healthy and happy.
But Avery is only alive today because of a revolutionary therapy called mitochondrial transplantation that used her own mitochondria — small structures in our cells that act as the “batteries” powering our organs — to boost her heart’s energy.
Mitochondrial transplantation comes to the rescue of hearts suffering from ischemia, a condition of reduced blood flow that damages mitochondria. As a result of its energy-sapping effects, ischemia is especially dangerous for the frailest cardiac patients: infants with congenital heart disease like Avery.
A rocky start for Avery
Soon after Avery was born on Dec. 4, 2015, she suffered seizures and was moved into the Neonatal Intensive Care Unit. There, doctors told Avery’s parents that she had been born with complex congenital heart disease. She was diagnosed with Shone’s complex, hypoplastic left arch and hypoplastic aortic valve.
After transferring to the Heart Center at Boston Children’s Hospital, Avery went through multiple open heart surgeries in a matter of months. As she fought off complications including ischemia, her heart weakened and her chance of surviving became slim. She was relying on a heart-lung bypass machine called ECMO (which stands for extracorporeal membrane oxygenation) to keep her alive, but each passing day on the machine made it more and more unlikely that she would ever make a full recovery.
Cardiac researcher Dr. James McCully and heart surgeon Dr. Sitaram Emani proposed that mitochondrial transplantation could rescue Avery’s heart with a boost of energy. After years of collecting promising data in the laboratory, the team was ready to bring the experimental treatment option to patients.
Although at that time they had only given mitochondrial transplantations to a few other children, they offered the therapy to Avery’s parents.
“We understood that the risks were minimal considering the larger risks Avery was facing,” says Jessica. “We decided to go through with it.”
Avery’s mitochondrial transplantation
Emani took a pencil-eraser-sized piece of tissue from the bottom of the incision used for Avery’s heart surgery. Then, McCully prepared the transplant. Less than 30 minutes later, Emani injected purified mitochondria directly into the areas of the Avery’s weakened heart muscle.
“What this does is provide an extra energy source to the heart,” explains McCully. “Over a longer period of time, the mitochondria move into the cells, providing extra function.”
Avery’s heart function immediately improved. Then, it wavered. Jessica began to worry. But Avery just needed a bit more time for the mitochondria’s effect to fully kick in. Soon, Avery’s heart grew stronger and she was able to come off the ECMO machine that had been keeping her alive.
Today, Emani and McCully have delivered mitochondrial transplantation to 11 patients and have seen remarkable results, leading them to explore additional applications for the therapy.
“We believe we could use this during all major heart operations to speed up recovery,” says Emani. “Now that we’ve demonstrated that it works on the heart, we want to expand it to treat other organs and diseases.”
Erin Horan contributed to this story.
Learn more about mitochondrial transplantation.