Jesse Karmazin is the entrepreneur who made the practice possible, by launching a clinical trial on the potential of “young blood” through his startup Ambrosia. He says that within a month, most participants “see improvements” from the one-time infusion of a two-liter bagful of plasma, which is blood with the blood cells removed.
Several scientists and clinicians say Karmazin’s trial is so poorly designed it cannot hope to provide evidence about the effects of the transfusions. And some say the pay-to-participate study, with the potential to collect up to $4.8 million from as many as 600 participants, amounts to a scam.
What’s certain is that it’s based on some intriguing if inconclusive science. Karmazin, a 32-year-old Princeton graduate and competitive rower, says he was inspired by studies on mice that researchers had sewn together, with their veins conjoined, in a procedure called parabiosis.
Over the last decade or so, such studies have offered provocative clues that certain hallmarks of aging can be reversed or accelerated when old mice get blood from young ones. Yet these studies have come to conflicting conclusions. An influential 2013 paper in Cell showed that a particular component in young blood, GDF11, increased muscle strength, for example, but other researchers could not replicate the finding.
Further, parabiosis experiments offer little insight into how Ambrosia’s one-time transfusions will affect people. “In our study, circulation between the young and old mouse was maintained for nearly four weeks,” says Amy Wagers, a professor of regenerative biology at Harvard University and an author on the Cell report.
Despite such uncertainties, the potential of young blood to treat disease is being explored in a number of clinical trials. One test sponsored by the University of California, San Francisco, is examining the effects of transfusions in patients with a degenerative disorder called progressive supranuclear palsy. A study under way in China investigates whether young plasma alleviates the neurologic deficits induced by acute stroke.
In 2014, Stanford University neuroscientist Tony Wyss-Coray demonstrated that old mice had increased neuron growth and improved memory after about 10 infusions of blood from young mice. That prompted Wyss-Coray to launch a small company, Alkahest, based in Menlo Park, California, to test transfusions of plasma from young people in the treatment of Alzheimer’s disease.
Alkahest’s clinical study is more conventional than Ambrosia’s: it does not charge participants, it expects to enroll only 18 volunteers, and it is initially looking at how well the elderly can tolerate small doses of plasma. Wyss-Coray says the company’s initial funding was provided by a billionaire in Hong Kong who felt that a plasma transfusion had helped his grandfather combat Alzheimer’s. In March 2015, the plasma company Grifols invested $37.5 million in the startup.
Like several other researchers and bioethicists, Wyss-Coray worries about the fact that Ambrosia’s trial is funded by participants rather than investors. “People want to believe that young blood restores youth, even though we don’t have evidence that it works in humans and we don’t understand the mechanism of how mice look younger,” Wyss-Coray says. “I think people are just attracted to it because of vampire stories.” He mentions a Hungarian tale of a wealthy woman who bathed in the blood of virgins to retain her youth.
As of December 15, Karmazin says, Wright had infused 25 people with young blood. Karmazin claims his participants are seeing miraculous results; a patient with chronic fatigue syndrome, for example, “feels healthy for the first time” and “looks younger.” Such anecdotes could help market the study, but they’re no proof the plasma infusions work, and would-be patients shouldn’t believe them.
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