Young blood + old blood


Many readers will recall the results of the past few years that claim that infusion of young-animal plasma into aged animals seems to have many beneficial effects. Of course, this field is well stocked with controversy. Not everyone believes the results, from what I can see (although, for what it’s worth, there seem to be an increasing number of papers on it). If they’re real, not everyone thinks that they can be readily extrapolated to humans. And even if they can, it doesn’t take very much thought to see a number of ethical implications as well.

There have been a couple of recent papers that will stir things up even more. This preprint from a multinational research team (UCLA and many others) details work on several “methylation clocks” of molecular aging. DNA is methylated (especially on cytosine residues) to a number of transcriptional effects, and the number and distribution of such methyl groups definitely change over the lifespan of most animals.

The Horvath lab at UCLA has made a specialty out of this epigenetic research area for some years now, and the changes in DNA methylation with aging seem pretty well established (even if quantifying them is trickier). This new paper draws on a large number of rat samples, with an overall methylation clock detailed, as well as more specific ones for brain, liver, and blood tissue. The addition of an even larger set of human tissue samples provides two more cross-species methylation clocks as well.

Previous work from the group has provided similar clocks for mice, which correlate well with known lifespan-extending interventions such as caloric restriction (reviewed here).

FULL TEXT: Science Translational Medicine