Stories about: James McCully

Hearts get a boost from mitochondrial transplantation

In this artistic rendering, mitochondria (enlarged at top left) are depicted inside heart muscle cells. Watch an animation about mitochondrial transplantation.

For decades, cardiac researcher James McCully, PhD, has been spellbound by the idea of using mitochondria, the “batteries” of the body’s cells, as a therapy to boost heart function. Finally, a clinical trial at Boston Children’s Hospital is bringing his vision — a therapy called mitochondrial transplantation — to life.

Mitochondria, small structures inside all of our cells, synthesize the essential energy that our cells need to function. In the field of cardiac surgery, a well-known condition called ischemia often damages mitochondria and its mitochondrial DNA inside the heart’s muscle cells, causing the heart to weaken and pump blood less efficiently. Ischemia, a condition of reduced or restricted blood flow, can be caused by congenital heart defects, coronary artery disease and cardiac arrest.

For the smallest and most vulnerable patients who are born with severe heart defects, a heart-lung bypass machine called extracorporeal membrane oxygenation (ECMO) can help restore blood flow and oxygenation to the heart. But even after blood flow has returned, the mitochondria and their DNA remain damaged.

“In the very young and the very old, especially, their hearts are not able to bounce back,” says McCully.

Ischemia can be fatal for the tiniest patients

After cardiac arrest, for instance, a child’s mortality rate jumps to above 40 percent because of ischemia’s effects on mitochondria. If a child’s heart is too weak to function without the support of ECMO, his or her risk of dying increases each additional day spent connected to the machine.

But what if healthy mitochondria could come to the rescue and replace the damaged ones?

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An energy boost to the heart: Infant’s own mitochondria save her life

20160606_AveryHeart-12_with MomShe’s small for a 6-month-old, but otherwise Avery Gagnon looks perfectly healthy. She smiles, kicks, laughs and grabs her toys and pacifiers. What you’d never know is that Avery has complex congenital heart disease and might not be alive today if it weren’t for an innovative procedure that used mitochondria from her own cells to boost her heart’s energy.

The procedure is the brainchild of James McCully, PhD, a cardiovascular research scientist at the Heart Center at Boston Children’s Hospital, who spent most of his career working to solve a common complication of heart surgery: damage to heart muscle cells.

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