Mitochondrial transplantation in humans: “magical” cure or cause for concern?

Mitochondrial transplantation is a therapeutic approach developed by McCully and colleagues that entails the injection of healthy mitochondria harvested from unaffected tissue into an ischemic organ of the same subject (1). It has recently been applied to human pediatric patients with myocardial ischemia (2), receiving widespread media attention accompanied by sensationalistic claims on its mechanism of action, e.g.: (a) after injection into the heart, "mitochondria moved like magnets to the proper places in the cells and began supplying energy;" and (b) after infusion into the coronary arteries, "somehow the organelles will gravitate almost magically to the injured cells that need them and take up residence" (3).