It was one of the most mind-bending scientific reports in 2014: Injecting old mice with the plasma portion of blood from young mice seemed to improve the elderly rodents’ memory and ability to learn.
Inspired by such findings, a startup company has now launched the first clinical trial in the United States to test the antiaging benefits of young blood in relatively healthy people.
Karmazin says each person will receive roughly 1.5 liters over 2 days.
Before the infusions and 1 month after, their blood will be tested for more than 100 biomarkers that may vary with age, from hemoglobin level to inflammation markers.
“I don’t see how it will be in any way informative or convincing,” says aging biologist Matt Kaeberlein of the University of Washington, Seattle.
The participants won’t necessarily be elderly, making it hard to see any effects, and there are no well-accepted biomarkers of aging in blood, he says.
The venture didn’t pan out—Karmazin left, and the company is now apparently defunct.
Karmazin then started Ambrosia with Craig Wright, a former chief scientific officer at a vaccine company, who now runs a clinic in Monterey.
The presence of such trials in the database confers “undeserved legitimacy,” he says.
The scientific design of the trial is drawing concerns as well.
“There's just no clinical evidence [that the treatment will be beneficial], and you're basically abusing people's trust and the public excitement around this,” says neuroscientist Tony Wyss-Coray of Stanford University in Palo Alto, California, who led the 2014 young plasma study in mice.
Decades ago, so-called parabiosis studies, in which the circulation of old and young animals was connected so that their blood mingles, suggested that young blood can rejuvenate aging mice.
But there's a big caveat: It's a pay-to-participate trial, a type that has raised ethical concerns before, most recently in the stem cell field.