https://www.inc.com/jeff-bercovici/peter-thiel-young-blood.html In Monterey, California, about 120 miles from San Francisco, a company called Ambrosia recently commenced one of the trials. Titled “Young Donor Plasma Transfusion and Age-Related Biomarkers,” it has a simple protocol: Healthy participants aged 35 and older get a transfusion of blood plasma from donors under 25, and researchers monitor their blood over the next two years for molecular indicators of health and aging. The study is patient-funded; participants, who range in age from late 30s through 80s, must pay $8,000 to take part, and live in or travel to Monterey for treatments and follow-up assessments.

Ambrosia’s founder, the Stanford-trained physician Jesse Karmazin, has been studying aging for more than a decade. He became interested in launching a company around parabiosis after seeing impressive data from animals and studies conducted abroad in humans: In one trial after another, subjects experience a reversal of aging symptoms across every major organ system. While the mechanisms at play aren’t totally understood, he said, young organisms’ blood not only contains all sorts of proteins that improve cell function; somehow it also prompts the recipients’ body to increase its production of those proteins. “The effects seem to be almost permanent,” he says. “It’s almost like there’s a resetting of gene expression.”