The group confirmed their results by putting satellite cells from old and young mice in a lab dish with either old or young blood serum. Old satellite cells in old serum and young satellite cells in young serum both behaved as expected. But when old satellite cells were bathed in young serum they cranked up their production of Delta and began dividing. Likewise, young satellite cells decreased the amount of Delta they produced when in a dish with older serum and divided less frequently.
Rando said that it may be a general phenomenon that a person's inability to repair tissues with age-whether it's muscle, liver, skin or brain-is a matter of the regenerative cell's environment rather than the cells themselves.
Rando said that finding the youth-promoting factors in the blood is no small task. "It's as big a fishing expedition as you can possibly imagine," he said. With thousands of proteins, lipids, sugars and other small molecules in the blood serum, deciding where to look first would be tantamount to a roll of the dice. What's more, there's no evidence that the same blood component is responsible for reviving the different types of cells.
"Another approach is to pick factors that are good candidates and see if any of them or some combination recapitulate the effect of the younger blood," Rando said. His group is now looking for likely targets. He said that for some degenerative diseases such as Alzheimer's or muscular dystrophy, such blood-borne factors may be able to reactivate the regenerative cell's ability to repair tis
Contact: Amy Adams
Stanford University Medical Center