“Mitochondria, the organelles in question, are best known as power packs—places where glucose molecules are disassembled to release the energy that drives metabolism… Mitochondria also initiate the suicide of cells that are damaged, cancerous or surplus to requirements; act as communications centres for signalling proteins; and regulate levels of calcium ions—which are involved in signalling as well…

With such a wide range of vital tasks to perform, it is hardly surprising that faulty mitochondria cause or contribute to many diseases. Some of these are congenital, the result of faulty mitochondrial genes. And some, such as diabetes and cardiovascular problems, occur when mitochondria wear out in old age. If a technique to transplant healthy ones could be made to work, its potential would be enormous.

One person trying to make this happen is James McCully of Harvard Medical School. He has developed a treatment for premature babies who, because the mitochondria in their heart muscles have been damaged by ischemia (the medical term for restricted blood flow), need the assistance of a heart-lung machine. Without such intervention, they would die. Even with it, only 60% survive.

In a trial, the results of which were published just over four years ago, Dr McCully improved that rate to 80%. His technique involves taking a small piece of tissue from the child’s abdominal wall, breaking it up to liberate the mitochondria, separating them from other cellular gubbins in a centrifuge and perfusing them back into the failing heart.

There is a chance that Dr McCully’s results may have been a statistical fluke—only ten babies were given the procedure in his experiments—but it suggests his technique is at least safe. He and his colleagues found that their procedure immediately increased production of signalling molecules in the babies, which stopped inflammation and cellular suicide. And, shortly afterwards, the perfused mitochondria took up residence in the damaged heart muscle, restoring its function in the longer term.

Dr McCully now hopes to extend this approach, which is currently being assessed by America’s Food and Drug Administration, to other ischemia-affected tissues, including adult hearts, lungs, kidneys and limbs. He is not alone. Lance Becker of the Feinstein Institute in New York plans to test a similar technique on premature babies. And Melanie Walker of the University of Washington, in Seattle, has just published the results of an experiment on a different type of ischemia—that which causes strokes.”

From The Economist.