Turning Old Hearts Young

You never know what will happen when you sew two mice together:

As heart muscles get older, they grow thicker. The thickened heart can still pump blood out normally, but it can't relax enough to refill between pumps. The condition is called diastolic heart failure, named after the heart's resting, or diastolic, phase. There is currently no treatment to reverse the thickening of the heart and restore normal function.

But researchers continue to look for such a cardiac fountain of youth. One approach has been to apply a 150-year-old technique to infuse young blood into old mice. Called heterochronic parabiosis the method involves surgically linking the circulatory systems of two mice of different ages by opening a flap of skin on each mouse's side and stitching the two together so that the same blood pumps through both creatures. (More than a century ago the technique was developed to study nutrient exchange between animals.) Previous studies found better muscle health and stronger healing in old mice receiving blood from a younger counterpart.

In the latest study, stem cell biologist Amy Wagers and cardiologist Richard Lee of Harvard tried to figure out what it is, exactly, in the young mouse's blood that helps the old mouse's heart. After ten years of effort they succeeding in identifying the active agent as a protein called growth differentiation factor 11, or GDF-11. They confirmed this by injecting an old mouse with GDF-11 for 30 days, whereupon its heart got healthier and younger looking.

GDF-11 exists in humans, but nobody knows if it has anything to do with how our hearts age.  Stay tuned.

Wouldn't it be weird if a great secret of aging and death was discovered from an experiment that might have been done in Dr. Frankenstein's laboratory? Look over here, Igor, I have surgically connected the vena cava of this ancient mouse to that of its grandchild, and behold how the old one now frisks about!