The stem cell facelift is touted by some as the next big thing in cosmetic surgery. But as Dr. Michael McGuire puts it: “Stem cells have incredible potential. But nobody knows exactly what they do. So they’re marketed to do everything.”

A recent article in the L.A. Times asked experts to weigh in on the procedure, which involves isolating stem cells from a patient’s own fat and injecting them into the face for a purported rejuvenating effect. With a stem cell facelift, there’s no need for incisions or general anesthesia like there is for a traditional facelift, making it less invasive.

The article says that there are already a small number of cosmetic surgeons performing the procedure in the U.S., such as Beverly Hills cosmetic surgeon Dr. Nathan Newman, who has performed the procedure over 200 times in the last five years and reports “fantastic results.”

But others say there is little evidence of whether it is effective and how it works. Co-director of the Adipose Stem Cell Center at the University of Pittsburgh Dr. J. Peter Rubin says that while he’s excited about stem cells’ potential for cosmetic uses, there are many unanswered questions.  He says that claims are being made that are not supported by evidence.

Rubin believes it’s possible that injected stem cells could create new collagen and blood vessels, as they’ve been shown to do in animals studies, but such results haven’t been proved in humans. In addition, he says that no one really knows how the stem cells are behaving and that fat injections alone can improve a person’s appearance even without stem cells.

Dr. McGuire also thinks that stem cells could offer real advances in cosmetic medicine in the future, but that it is still at least ten years away.