Editor's Note: This story is part of an In-Depth Report on the science of beauty. Read more about the series here.

At-home treatment for wrinkles has come a long way since grandma slathered on Pond's. The old standby is still around, but it's now just part of the mix of over-the-counter and Rx beauty salves as researchers worldwide race against the (biological) clock—to find ways to slow the march of time and the tracks it leaves on the skin.

Competing for a piece of the $1.6 billion that U.S. consumers spend annually on anti-aging skin care, major cosmetic makers worldwide now all have staff scientists researching and developing anti-aging technology to incorporate into products. It’s no longer enough to simply slather some creamy concoction on dry skin.

"We are trying to gain a deeper, molecular understanding of the skin aging process," says Jay Tiesman, a biologist and genomics research group leader at Procter & Gamble (P&G) in Cincinnati, which makes beauty products under the Olay brand. Researchers are exploring the use of such biological tools as stem cells and gene triggers to prevent—and even reverse—the ravages of time.

As we age, cells typically begin to regenerate more slowly and those known as fibroblasts produce less collagen, a protein that keeps skin firm and supple. These changes may be hastened by environmental factors such as the sun's ultraviolet rays, pollution and smoking, which can trigger free radicals or unstable molecules that prematurely damage DNA (genetic material) in cells.

The most effective ways to prevent premature signs of aging is to wear sunblock, skip the smokes—and eat a diet rich in fruits and veggies such as blueberries and artichokes that contain antioxidants, molecules that can block free radicals from damaging cells. In an attempt to spare the skin, Daniel Yarosh, a photobiologist and senior vice president of research and development at Estée Lauder Companies in Melville, N.Y, says his company and others are now including antioxidants in some topical creams to disable free-radical attacks on the epidermis (outermost skin layer).

Researchers are also exploring new ways of boosting the skin's ability to retain moisture as well as to keep germs from seeping into the body. "You want a nice barrier to protect the living layers of the dermis [the layer beneath the epidermis] to protect the skin from dehydrating and [from] external threats such as bacteria and other things we come into contact with on a daily basis," says Greg Hillebrand, a biochemist and principal scientist at P&G.

He notes that P&G scientists are also examining DNA in skin cells from the arms and backsides of women of different ages in an attempt to figure out specific genes that get turned on and off over time and when exposed to the sun, smoke and other environmental factors.

Researchers at L'Oréal's labs, meantime, are conducting research into the role that adult stem cells may play in the aging process in the hope of coming up with therapies designed to keep them functioning at their full potential.

"Stem cells are at the origin of regeneration of skin," says Jacques Leclaire, a biochemist and vice president of L'Oreal's life sciences division in Clichy, France, so "it's important to understand" how they behave during aging. He notes that the number of stem cells in skin stays essentially the same, but that their function changes over a lifetime. In an attempt to keep stem cells at the top of their game, Leclaire says his team is trying to develop products that protect the cells' "environment," most notably where the epidermis and dermis (middle skin layer) meet.

Other researchers are probing the connection between the skin and the circadian cycle (body clock), to figure out whether there's an optimum time to apply certain creams.

The circadian cycle coordinates the repair of damaged cells and DNA in the body, which mainly occurs during rest periods. Research has shown that as people age, the genes that affect the circadian cycle get out of synch, slowing cell repair. Mary Matsui, Estée Lauder's executive director of external research, says that scientists there are probing the molecular pathways that skin cells use to communicate with the body clock in an attempt to keep the process running smoothly. Women's Wear Daily reports that Estée Lauder is set to release a product line dubbed Chronolux Technology this summer that contains an amino acid sequence that helps to maintain a healthy cell repair schedule.

"Dermatologists have lived under the impression that once you have wrinkles and damaged collagen, that's it," Yarosh says. Research has shown, however, that new collagen can be generated—and Estée Lauder and others say they are developing products that may stimulate such production.

P&G, for instance, has developed Pal-KT, a trademark name for a kind of peptides (short strands of amino acids, the building blocks of proteins) that it uses in its Olay Pro-X line, introduced earlier this year. Hillebrand says that during studies these peptides tricked skin cells called fibroblasts that produce collagen into upping their output of the firming protein. The reason: when collagen breaks down it produces peptides, which the fibroblasts sense, triggering them to begin making new collagen.

Other key active ingredients that P&G has pinpointed as important weapons in the battle against wrinkles (and has included in its Pro-X line) include:

•    Retinyl propionate, a patented and less irritating form of retinol (a form of vitamin A) and propionic acid (a liquid fatty acid). It "has multiple effects on the skin," Hillebrand says. "It's been studied for effects on collagen synthesis and barrier protection."
•    Niacinamide, a form of Vitamin B3, which Hillebrand says improves moisture retention, fine lines and hyperpigmentation.
•    Hexamidine, a chemical also used in diaper lining, helps lock in moisture; studies show it also helps to improve the pathways for lipids (fats) to travel through the skin layers, thereby improving thickness.

Despite the time and money that companies pour into anti-aging research and consumers pour into their products, the condition of your skin largely comes down to your genes—and how well you protect it. The P&G scientists liken inherited skin traits to those for being tall and having nice teeth. They set you out on the right track, but you will probably only reach your full height potential with proper nutrition and have strong teeth with good dental hygiene.

"Our skin is sort of a merciless mirror of our inner health," Hillebrand says. To keep that mirror looking its best, he notes, you should get plenty of sleep, drink lots of water, eat a balanced diet, wear sunblock—and avoid smoking, excess alcohol and stress.

"It's not all about going anti-aging," Hillebrand says. "It's about aging successfully and gracefully."