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First reversal of aging in an organ claimed

Nov. 29, 2007
World Science staff

Sci­en­tists are re­port­ing what they say ap­pears to be the first suc­cess­ful re­ver­sal of ag­ing, at least in one or­gan: the skin of mice.

It’s un­clear, they said, whether these results can hold up for long time periods, and how one might apply the find­ings to hu­man­s. Yet the work is sig­nif­i­cant in that it shows a pro­found “re­ju­vena­t­ion” is at least partly pos­si­ble in prin­ci­ple, the re­search­ers said.

Courtesy U.S. Nat'l Institutes of Health
Past stud­ies are thought to have iden­ti­fied ac­ti­vi­ties that slow ag­ing or un­do some of its ef­fects, but not re­verse it at a fun­da­ment­al, ge­ne­tic level.

The new find­ings are de­scribed in the Dec. 15 cov­er pa­per of the re­search jour­nal Genes & De­vel­op­ment. The key to the pro­cess was block­ing a gene called NF-kappa-B in the skin, said the sci­en­tists, led by How­ard Chang of Stan­ford Un­ivers­ity School of Med­i­cine in Cal­i­for­nia.

“These find­ings sug­gest that ag­ing is not just a re­sult of wear and tear, but is al­so the con­se­quence of a con­tin­u­ally ac­tive ge­net­ic pro­gram that might be blocked for im­prov­ing hu­man health,” said Chang.

Chang and col­leagues had pre­vi­ously iden­ti­fied NF-kappa-B as “mas­ter reg­u­la­tor” of ag­ing-associated gene ac­tiva­t­ion pro­grams in hu­mans and mice. In ef­fect, the gene pro­motes the ac­ti­vity of an ar­ray of oth­er genes im­pli­cat­ed in ag­ing. Chang’s team en­gi­neered a mouse with a gene that could coun­ter­act NF-kappa-B, but which was inac­tive by de­fault. This block­ing gene could be ac­tivated in the skin, though, by ap­ply­ing a spe­cial cream.

“So the mouse went through its life­span and aged nor­mal­ly,” Chang said. But when the cream was added to a patch of skin, he added, there was a strik­ing out­come. Af­ter two weeks of treat­ment, the re­search­ers re­ported, both the gene ac­tiva­t­ion pro­file and the tis­sue char­ac­ter­is­tics of the aged skin re­verted to that of a young an­i­mal. 

“The find­ing that aged skin can be ‘re­ju­ve­nat­ed’ by a ge­net­ic in­ter­ven­tion late in life im­plies that the ag­ing pro­gram is plas­tic,” or flex­i­ble, Chang said. It “there­fore can be po­ten­tially ma­ni­pu­lated to de­crease the del­e­te­ri­ous ef­fects of ag­ing.” Fu­ture stud­ies will fo­cus on wheth­er long-term treat­ment can main­tain the re­sults, whe­ther there are side ef­fects and wheth­er oth­er or­gans can ben­e­fit sim­i­lar­ly, he added.

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Scientists are reporting what they say appears to be the first successful reversal of aging, at least in one organ: the skin of mice. Although the change was short-term—and it’s unclear how scientists might apply the findings to humans—the work is significant in that it shows a profound “rejuvenation” is at least partly possible in principle, the researchers said. Previous studies have identified activities that may slow aging, but not reverse it outright. The new findings are described in the Dec. 15 cover paper of the research journal Genes & Development. The key to the process was blocking a gene called NF-κB in the skin, said the scientists, led by Howard Chang of Stanford University School of Medicine in California. “These findings suggest that aging is not just a result of wear and tear, but is also the consequence of a continually active genetic program that might be blocked for improving human health,” said Chang. Chang and colleagues had previously identified NF-κB as “master regulator” of aging-associated gene activation programs in humans and mice. In effect, the gene promotes the activity of an array of other genes implicated in aging. Chang’s team engineered a mouse with a gene that could counteract NF-κB, but which was inactive by default. This blocking gene could be activated in the skin, though, by applying a special cream. “So the mouse went through its lifespan and aged normally,” Chang said. But when the cream was added to a patch of skin, he added, there was a striking outcome. After two weeks of treatment, the researchers reported, both the gene activation profile and the tissue characteristics of the aged skin reverted to that of a young animal. “The finding that aged skin can be ‘rejuvenated’ by a genetic intervention late in life implies that the aging program is plastic,” or flexible, Chang said. It “therefore can be potentially manipulated to decrease the deleterious effects of aging.” Future studies will focus on whether long-term treatment can maintain the results, and whether other organs can benefit similarly, he added.