Legend has it that vampires stay young-looking by feasting on the blood of others, but a new, real-life cosmetic procedure turns the tables. The so-called "vampire facelift" involves injecting a patient's own blood into her wrinkles and hollow cheeks to turn back the clock. Here's a brief guide:

What exactly is a "vampire facelift"?
It's not a facelift really, but rather an in-office cosmetic procedure in which an injectable substance known as Sephyl is used to fill in wrinkles and furrows, to give the appearance of youth. But, unlike common fillers like Juvederm and Restylane, the substance in question is based on a patient's own blood. Blood is drawn from a patient's arm, and the platelets are spun out using a Selphyl-brand centrifuge. It's this "platelet-rich fibrin matrix" that is then injected.

Does it really work?
Some say so. The procedure has been touted on television shows like "The Doctors" and "The Rachael Ray Show," and it has proponents in the medical community. Dr. Joseph M. Gryskiewicz, the chair of the emerging trends committee of the American Society of Plastic Surgeon, says he's been impressed with the results, calling the product "as good as any filler out there." But, Dr. Phil Haeck, the organization's president, isn't so sure. "There are no scientific studies, only personal attestations," he says. "This is another gimmick that people are using to make themselves stand out on the internet" in a "dog-eat-dog" competition for patients.

What is its supposed advantage?
Proponents say that because Selphyl involves injecting something from a patient's own body, rather than a foreign substance, it has a natural advantage over the competition. Some doctors argue that it's less likely to create bumps and irregularities than synthetic fillers.

Is it better than Botox?
It's a different beast, and the two can't really be compared. Selphyl fills in a space, while Botox works by inhibiting muscles.

Is it safe?
Good question. The F.D.A. hasn't approved or cleared the use of platelet-rich fibrin matrix in this way, though it did clear a similar procedure for use by orthopedic doctors for tissue repair in 2002. At least one doctor's study suggests the vampire facelifts are safe, but there hasn't been a formal evaluation.

Sources: New York Times, CBS News