Young Blood

If you were offered a way to feel healthier and even look younger, would you take it? What if it required you to have repeated transfusions with the blood of teenagers or 20-somethings?

This is not vampire fiction. A private clinic in California called Ambrosia has been signing up people for a study of the procedure. Over the course of two days, subjects—who are charged $8,000 each—are infused with blood plasma drawn from young people. The expectation is that afterward the subjects will feel both healthier and younger.

Bizarre as it sounds, this experiment was inspired by a number of studies in which old mice were successfully rejuvenated by the blood of young ones. The treatment improved the condition of muscles and livers in the old rodents, jump-started the production of new neurons in their brains, helped repair damaged spinal cords and reversed thickening in the walls of their hearts. In general, they emerged stronger, healthier and smarter—better at learning and remembering.

The mice did not, however, have simple transfusions. Almost all the studies have relied on a technique called parabiosis. Two mice—one young, one old—were stitched together, side by side, conjoined as if they were Siamese twins. Over the next few weeks, new blood vessels developed and hooked up through wounds in their sides until they shared a single circulatory system. The animals apparently got used to their twinship and ate, drank and behaved pretty normally as the same blood coursed through both bodies, and the older one’s health began to improve.

Obviously, not many humans will want to be conjoined. Instead some experimenters, like those at Ambrosia, are trying out transfusions of blood plasma taken from the young.

I’m hoping the transfusions don’t make any difference. Perhaps I read too much science fiction, but I can imagine young blood becoming a commodity—and a future in which tottery billionaires will sign contracts with teenagers, promising to pay for their college educations in exchange for monthly transfusions.

However, top mouse-study scientists have focused on different problems. They say that experiments on humans are premature. And a one-time infusion of blood isn’t the same as sharing a circulatory system with a young partner, which the old mice did for weeks. Also, blood plasma is different from whole blood. (Plasma is a component of blood that’s full of antibodies but has had white and red blood cells removed.)

According to Jesse Karmazin, the founder of Ambrosia, the purpose of the experiment is to test the subjects’ blood before and after they’ve been transfused, to look for biomarkers that have changed and that might be associated with aging. But Karmazin, who is 32, only requires his subjects to be 35 or older (not my idea of old age), while the transfusions come from individuals between 16 and 25 (not much of an age gap). He also asks people to pay to be experimented on, which is a no-no among scientists, and he has no control group—subjects who get a sham therapy—which means he has no way to assess the treatment’s placebo effect. His volunteers may feel good afterward just because they expect to feel good.

Most of the researchers involved in studies of blood and aging are still at the mouse stage, investigating factors in the blood of young mice that, when circulating through the body of an old mouse, might account for improvements in its health. They’ve identified a few possibilities, but a study published in 2016 has suggested a different approach.

The experiment was carried out by a team of scientists headed by Irina and Michael Conboy of the University of California, Berkeley. The problem with parabiosis, the investigators decided, is that it may not be young blood itself that’s powering rodent rejuvenation. An old mouse, connected to a young one via their combined circulatory system, also benefits from its partner’s efficient, young organs, such as its heart and liver, through which their blood passes.

The Conboys’ team created a computerized pump that would, over 24 hours, gradually replace half the blood in an old mouse with the equivalent amount of blood from a young one, while gradually transfusing a young mouse with old blood—without actually connecting their circulatory systems. Afterward, half the contents in the bloodstream of each animal were “old” and half were “young.”

The investigators were surprised to find that, while the older mice benefited to some extent, the youngsters’ well-being took a nose dive: among other things, the transfusion sapped their strength and interfered with their ability to form new brain cells.

This was a very small study, but it suggests that scientists shouldn’t narrow their focus to just look for the fountain of youth in young blood. It may be at least as important to identify, in old blood, clues to what causes health problems in later life.

If that quest pans out, a report in MIT Technology Review suggests, “one day, instead of getting transfusions from young people, aged people will instead go to a medical facility to get their blood cleared of proteins that may build up and promote aging.”

Call me a pessimist, but for me, regular dialysis would have even less appeal than regular transfusions. But the research on old and young blood could turn out to be important. No one knows what makes our bodies and brains change with age. There may indeed be blood-borne clues. And if there are, it’s possible they’ll suggest ways to increase our healthspans so that we stay healthy until very late in life.

That’s the goal of most of the scientists who are doing basic research on aging. All the same, some of them, and some of their funders, admit that they’re also hoping to defeat death: to do away with aging and mortality.

Quite a few people I know would turn down a chance at immortality if it were on offer. But unless it involved frequent dialysis or transfusions—or being conjoined to a 20-something—I, for one, wouldn’t say no.