"Restore and renew." "Significantly reduces the loss of cells in the epidermis." "Regenerate cells and repair tissue."

The newest skin creams beckon with an air of scientific gravitas, holding out the hope that now, at last, medicine has triumphed over the visible aging process. With tantalizing biological references and understated packaging, the products are among the first to capitalize on the public's insatiable appetite for stem-cell technology.

"The goal of these products is to create a more youthful cell that would replenish elastin and collagen," says Dr. Kenneth Beer, a West Palm Beach, Fla., dermatologist. A clinical instructor at the University of Miami, he conducts clinical trials on skin-care products.

And, of course, what better way to do that than to harness stem cells, those potential miracles of self-repair and curative power on which society is pinning so many medical hopes?

But a word of caution before you plunk down $80 or $155 for these potions: They may be no better than existing anti-aging skin creams, the best of which spur the skin to work harder but still produce only modest effects. Adds Beer of the stem-cell-touting products' potential: "The notion that you could do that with a cream is a little bit ahead of itself. It's a great piece of marketing because there is so much interest in stem cells."

That's not to say that stem cells couldn't ultimately improve skin, perhaps in the next decade or so, says Dr. Leslie Baumann, a dermatology professor and director of the University of Miami's Cosmetic Center. But that time has not arrived, she says.

For now, she adds, consumers are being misled.

In fact, the creams don't even contain live stem cells — just the suggestion that they're comparable in some way to the largely unharnessed cellular powerhouses.

The stem-cell skin cream frenzy began last year when a Salt Lake City company called Voss Laboratories released its product, Amatokin, at Bloomingdale's with the advertising slogan "Stem Cells: The future of skin rejuvenation." It cost $190 for a 30-milliliter tube (about 1 ounce).

Then came other, equally enticing products and promises. Celebrity dermatologist Nicholas Perricone offered up StimulCell ($155 for a 1.7-ounce jar), and Dior began hawking Capture R60/80 XP ($80 per 1.7-ounce jar). Although none of the manufacturers say the products contain stem cells, the marketing materials are vague enough that consumers could easily think they were applying the much-heralded cells to their skin. Capture, for example, claims to "utilize stem-cell technology"; Amatokin says it's "made up of stem-cell-activating properties."

Stem cells, most notably found in the tissue of developing fetuses, have the ability to develop into many types of tissue. Many labs are working on ways to cultivate them into specific tissues or substances that could be used to treat a variety of illnesses.

But this research is in its infancy. Even if scientists figured out how to get live stem cells into products, applying them to the skin — and expecting them to work — would be a lot to ask. "There is no conceivable way today that stem cells could be delivered in a topical product," Beer says.

Instead, the products are designed to stimulate the skin's own stem cells, which are layered between the epidermis and dermis. These cells are constantly dividing, with newer cells slowly moving to the surface and older cells being shed from the top layer. As people age, this turnover process slows, causing the loss of elasticity, uniform color and other characteristics that give skin a youthful appearance. The goal of many skin-care manufacturers is to find substances that provoke adult skin stem cells to behave like younger cells, speeding up the skin-turnover cycle.

Amatokin's advertising says the product is "made up of stem-cell-activating properties" that can reduce wrinkles and that it "resets your skin's aging clock by a minimum of five years." The key ingredient is a peptide (a string of amino acids), says the creator of the preparation, Taras Nikolaev, a Russian scientist.

Capture contains a mixture of proteins, antioxidants and herbs that will keep "actively producing adult stem cells alive and able to continue to produce more collagen," says Dr. Neil Sadick, global medical advisor for Dior and a clinical professor of dermatology at Weill Cornell Medical College.

Perricone's StimulCell is made using adult skin cells, based on a cell line created by removing small pieces of undamaged skin from behind the ears of healthy young volunteers.

Perricone acknowledges some discomfort in how StimulCell is marketed — it claims to replicate "signals delivered by skin stem cells" — noting that the product contains no stem cells.

"I like to refer to them as precursor cells," he says. "They act as messengers in the skin. They send signals to surrounding cells to bring about whatever change is needed. ... Everyone is moving in this direction."