Like most plot points on HBO’s Silicon Valley, a recent episode in which tech oligarch Gavin Belson receives blood transfusions from a “blood boy” to help keep him young is actually rooted in reality—just ask Peter Thiel. “I’m looking into parabiosis stuff, which I think is really interesting. This is where they did the young blood into older mice and they found that had a massive rejuvenating effect,” the tech billionaire and Trump adviser told Inc. magazine. “I think there are a lot of these things that have been strangely under-explored.”

Jesse Karmazin agrees. His start-up, Ambrosia, is charging about $8,000 a pop for blood transfusions from people under 25, Karmazin said at Code Conference on Wednesday. Ambrosia, which buys its blood from blood banks, now has about 100 paying customers. Some are Silicon Valley technologists, like Thiel, though Karmazin stressed that tech types aren’t Ambrosia’s only clients, and that anyone over 35 is eligible for its transfusions.

Karmazin was inspired to found Ambrosia after seeing studies researchers had done involving sewing mice together with their veins conjoined. Some aspects of aging, one 2013 study found, could be reversed when older mice get blood from younger ones, but other researchers haven’t been able to replicate these results, and the benefits of parabiosis in humans remains unclear. “I think the animal and retrospective data is compelling, and I want this treatment to be available to people,” Karmazin told the MIT Technology Review.

Though Karmazin emphasized at Code Conference that Ambrosia’s goal isn’t explicitly to cure or reverse aging in humans, he reports his customers see positive improvements related to heart disease, cancer, and Alzheimer’s disease, science outlet New Scientist reported Wednesday. “I don’t want to say the word panacea, but here’s something about teenagers,” Karmazin told New Scientist. “Whatever is in young blood is causing changes that appear to make the aging process reverse.” Still, scientists haven’t identified a reliable link between blood transfusions from young people and tangible health benefits. “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,” Stanford University neuroscientist Tony Wyss-Coray, who conducted a 2014 study of young blood plasma in mice, told Science magazine last summer.

Whether Thiel himself is receiving such blood transfusions is also unclear. (A spokesperson for the venture capitalist did not immediately respond to a request for comment.) Last year, Inc. reported that a Thiel Capital employee had previously expressed interest in the technique to Karmazin, and Gawker published a tip claiming that Thiel “spends $40,000 per quarter to get an infusion of blood from an 18-year-old based on research conducted at Stanford on extending the lives of mice.” But if Thiel is experimenting with parabiosis, it’s not with Ambrosia. Karmazin told Code Conference on Wednesday that Thiel isn’t a client, and that his start-up is currently the only U.S.-based company that is selling the transfusions. A spokesperson for Thiel Capital told Inc. last year that nothing had changed since 2015, when Thiel said he hadn’t “quite, quite, quite started yet.”