Blood from old people has harmful toxins so blood banks need to be changed and all blood needs to be regularly filtered

Can transfusions of “young blood” make old people healthier? That’s the hope of a few startup companies and some wish-to-live-forever billionaires who think transfusions from youngsters might delay aging.

But scientists in California who invented a gadget to test the question say instead it’s the harmful toxins in old people’s blood that seem to be the problem.

A research team led by Irina Conboy at the University of California, Berkeley, developed a pump to continuously move blood between two mice. One was young, the equivalent of a human 20-year-old, while the other was the mouse equivalent of an 80-year-old.

Over 24 hours, the two animals’ blood was completely intermixed.

Five days later, old mice did see some benefits from having young blood in their veins, including better muscle repair. But Conboy, who reported her findings in Nature Communications, says the really striking finding was just how bad old blood was for the younger animals. The aged blood inhibited the formation of brain cells in young mice and caused the animals to fall behind their peers in a strength test where they are hung upside down on a wire mesh. “The young mice became almost as decrepit as the old ones,” she says.

One day people will instead go to a medical facility to get their blood cleared of proteins that may build up and promote aging. Conboy says she and other scientists are working to identify what those molecules are.

Given the swift and negative effects of old blood on younger mice—the results appeared immediately—this type of research could eventually raise questions about the age of blood-bank donors. A 2008 study in Blood found that the average age of blood donors in the U.S. was 35, but since repeat donors tend to be older, about 35 percent of blood came from people over 50, including many in their 60s.

With parabiosis animals share much more than blood. They share livers, immune systems, even the same blood pressure and temperature.

Rejuvenation of older people requires more than young blood. However, it looks like there would be antiaging advantages if blood, organs and immune systems could be rejuvenated.

SOURCES – Technology Review