Researchers say they have discovered a way to control the gene that plays a key role in the aging process. Even more, formerly aged tissues can actually be made "younger" in the form of new tissue growth in various organs, including the brain itself.

After only one month of having the gene turned on, the formerly aged mice showed significant signs of age "reversal", with testes once again making sperm and brains generating new nerve cells and better connections.

Regions at the ends of chromosomes called telomeres shorten over time as people and animals age; this is thought to happen because levels of the enzyme telomerase naturally decline over time. Now, researchers say they have developed a strain of mouse in which they can control the telomerase gene — and, therefore, aging.

By turning the gene off, the team was able to create mice that were prematurely aged. Their spleens, testes, intestines, and brains all had serious signs of age and all showed impaired function. The researchers wanted to see whether turning the telomerase gene back on would not only stop but also reverse the aging process in the mice.

Indeed, it did. After only one month of having the gene turned on, the formerly aged mice showed significant signs of age "reversal", with testes once again making sperm and brains generating new nerve cells and better connections. Even the mice’s cognitive skills improved: the animals were once again able to use their senses of smell to navigate surroundings and avoid aversive places, showing that their once-exhausted survival skills were back up to par.

Additionally, the mice did not develop cancer, which the researchers say is a crucial finding since cancer cells can themselves turn on telomerase, which makes them "virtually immortal", according to the Dana-Farber Cancer Institute news release. Finally, the researchers point out that another important implication of the study is in regenerative medicine, since it shows that cells that appear to be aged beyond hope can actually help restore tissues and regenerate healthy organs.

While the results apply only to mice at this point in time, future research will no doubt explore whether similar mechanisms also exists for other animals, including humans.

The research was carried out by researchers at the Dana-Farber Cancer Institute and published in the November 28, 2010 issue of Nature.