Eternal youth, a utopia?
Our family photos bear witness to this: there are still only two generations of our ancestors who were 80 years old. And the septuagenarians of the time, wrinkled and shaky, showed the stigmata of a canonical age. Today, change of program: if old age remains a fatality, it occurs in fact more and more later. Scientific and social progress oblige. "On average, in the world, we earn six hours of life expectancy every day," says Didier Coeurnelle, co-president of Heales (Healthy Life Extension Society) and author of And if we stopped aging! (Fyp ed). In France, life expectancy has already more than tripled, from 25 years in 1750 to more than 80 years now! And she continues to climb about three months each year.
Clearly, when you get older for a year, it's only nine months. As a result, centenarians are becoming more numerous: one per 10,000 inhabitants in Western countries, including more than 100,000 in the United States and nearly 19,600 in France. They are the fastest growing segment of the population. At the current rate of progress, one girl out of two who is born today in France will live centenary.
A flat of Didier Coeurnelle, however: "The maximum duration of human life, it does not progress anymore. In fact, there seems to be a natural biological "wall" beyond which living is no longer possible. With very few exceptions, no human being goes beyond 120 years . Most scientists agree that with an irreproachable lifestyle, this limit could be pushed back at most up to 130 years. Would our dream of eternal youth be pure utopia? Not necessarily, according to the work of hundreds of researchers who are already succeeding in significantly increasing the longevity of many animals in the laboratory.
And science discovered the genes of longevity ...
Aging is a complex phenomenon where the environment obviously plays a considerable role: pollution, hygiene, diet ... But the genetic heritage, specific to each individual, is also largely involved. Several genes associated with a long life have already been identified on simple organisms: yeasts, flies, worms ... The first, called daf-2 and involved in insulin metabolism, was discovered in the United States. United in a nematode, a roundworm that lives in the soil. By modulating its activity, biologists have succeeded in doubling the longevity of this tiny invertebrate. Another American team has extended the life of a group of mice by 20% by "muzzling" another gene, the mTOR, which comes into play in energy balance. With mTOR activity reduced to 25% of normal, these rodents lived up to 31.5 months, five to eight and a half months longer than in the wild. The equivalent of an additional sixteen years for men!
The researchers managed to isolate one hundred and thirty genes that could delay the aging process.
This work, published in late August 2013 in the American journal Cell Reports , however, show a major pitfall: following this genetic transformation, the senescence of different organs is not uniform. Although the modified mice have generally aged well, their susceptibility to infections and their bone mass have deteriorated early. On the other hand, their figure remained young longer. And their memory as well as their muscular strength have clearly gained in performance. "It reinforces one of our intuitions," says Dr. Toren Finkel, co-author of the study. The organisms have several aging clocks that do not work the same way in every organ. In men, research is also progressing fast. The genome (that is, the gene pool) of more than 800 centenarians, averaging 104 years old, has been thoroughly decorticated. By comparing it to the hereditary heritage of the general population, one hundred and thirty genes likely to delay the aging process have been isolated. According to gerontologists at Boston University, 60% of centenarians and 85% of people over 107 years old would have this particular genetic profile thanks to which age-related diseases (senile dementia, cancers, cardiovascular diseases, etc.). .) occur later. Will one day be able to transfer these protective genes to ordinary people? Hard to say today. But given the speed with which science progresses, no perspective can be definitively ruled out.
Cell immortality thanks to telomerase
To reverse the time arrow on the scale of whole chromosomes seems easier for the moment than to play another partition with a handful of ultra specific genes. Each adult cell line, as we know, is programmed to multiply a certain number of times before collapsing. The maximum number of organ-variable divisions is about 10 in rats and 52 in humans. This phenomenon, long enigmatic, is now well understood. It relies on the presence, at the end of each chromosome, of small structures that protect the DNA from degradation: telomeres. The longer they are, the more easily the cells reproduce, which allows the organs to regenerate well . But this golden age lasts only one time because each time, the telomeres erode until the day when "the cells do not replicate that imperfectly, even more at all", explains Didier Coeurnelle.
This major discovery earned Elizabeth Blackburn and Carol Greider the Nobel Prize in Medicine in 2009. It truly opens a path to cellular immortality as there is an enzyme capable of reversing the vapor: telomerase. To test its effectiveness, Californian biotechnology company Geron Corp has cultured retinal cells, skin cells and blood vessels in the presence of a telomerase activator. Instead of withering in a few months, they survived without damage for more than a year, keeping their early youth! A biologist at the Spanish Center for Cancer Research has been even more daring. She has handled young mice so that they produce more telomerase. These small transgenic rodents broke records with a lifespan 40% higher than that of their congeners. The experiment was repeated in 2012 in adult mice, with surprising results: those treated at the age of one year still lived 24% longer than ordinary specimens and those treated at the age of two. 13% longer . But it is impossible to claim victory because this genetic manipulation is not yet possible in humans. Nevertheless, several laboratories are trying to develop a molecule-drug that can restore the integrity of our telomeres. To be continued.
Aging: a reversible process
Another alternative considered: the cell therapy based on the injection of induced stem cells, that is to say adult cells having undergone an extreme rejuvenation operation. Returning to a poorly differentiated state, close to that of embryonic cells, they are theoretically capable of regenerating aging organs. Two years ago, this countdown seemed limited in time. But the team of Professor Jean-Marc Lemaître, Institute of Functional Genomics of the University of Montpellier, proved in November 2011 that it was indeed feasible at any age. Using a six-gene cocktail, she rejuvenated the skin cells of a 74-year-old donor. "All have regained their ability to self-renewal and their potential for differentiation of yesteryear, not retaining any trace of their previous aging, says Pr Lemaître. The age of the cells is definitely not a barrier to their reprogramming. The same protocol has also been successfully applied to centenarian cells. Like what aging is a reversible process! "From technological leap technological leap, we will be able to win several decades in good health," said at the conference TEDxParis 2012 , Laurent Alexandre, surgeon-urologist and author of the essay Death of Death (eds JC Lattès ). A revolution that is also believed by the bosses of Google who invest en masse in the sector through their new subsidiary Calico, dedicated to research on increasing human longevity.
A child born in 2014 will be able to reach the year 2150 and access new waves of innovations still unthinkable today.
"A child born in 2014 will be 90 years old at the beginning of the 22nd century and will benefit from all the biotechnological innovations of our current century," enthuses Dr. Laurent Alexandre. It can then reach the year 2150 and access new waves of innovations still unthinkable today. "By degrees, his life expectancy could be two to three times greater than ours. What to give the tournis. And we, who have been on Earth for several decades, what do we have to hope for?
THE NEW LABOS STAR
The naked mole rat, tiny African rodent, seems to possess the secret of eternal life. Not only does he not know cancer, but dies at 30 (unheard of for a mammal of barely 30 g) without any physical decay. Nothing to do with his cousin the mouse, who dies seven times earlier by gradually degrading. Researchers are therefore busy to discover the origin of this mystery. His gene pool was fully deciphered in the United States in 2011. Surprise! A very specific gene has been identified. This seems to be at the origin of a molecular signal that slows cell divisions as soon as they are too numerous in a small space, which inhibits the proliferation of cancer cells . According to research from the University of Rochester, published in September 2013 in the journal Nature , this signal would also exist in humans. But his sensitivity would be less. By amplifying it, one could avoid the formation of tumors. And thus remove one of the leading causes of human mortality.
Take control while waiting
While waiting for the development of the Elixir of Youth Miracle, we can work to move the hold of time to the maximum on our body and mind.
"Taking control starts with controlling your weight and maintaining your physical abilities," assures Frédéric Derat-Carrière, a marine therapist in Saint-Malo who has become an expert in evaluating muscular and cardio-respiratory skills. Adipose tissue behaves like an endocrine gland that secretes inflammation factors that can lead to the development of chronic diseases and cancers. This is why maintaining a satisfactory ratio between fat and lean mass is a guarantee of longevity. "
Similarly, aerobic fitness, which is measured by gauging its maximal oxygen consumption during stress tests, is a good predictor of cardiovascular risk and cognitive decline. The measurement of gait speed and muscular vigor (grip force calculated using a hand dynamometer) is equally valuable in estimating the likely evolution of our abilities over the next twenty-five years. Realize this battery of tests * to point out our weaknesses to rectify the shot with a suitable lifestyle.
"Getting back on the move and reducing caloric intake, without creating nutritional deficits, can save many years in good health," adds Frédéric Derat-Carrière. As with smoking cessation, it's never too late to start. Fifteen minutes of active walking a day, it's already ... three years of winning! And if you force the dose, the benefits are increased tenfold. Adding antioxidants to combat the harmful effects of free radicals is just as essential. The most effective of them? Polyphenols, which are found in abundance in fruits and vegetables, but also in tea, coffee and dark chocolate. A study from the University of Barcelona, published in September 2013 in The Journal of Nutrition , once again confirms their formidable effectiveness. According to Spanish researchers, people who ingest a lot of polyphenols (more than 650 mg per day, or the equivalent of 300 g of apples or cherries) have a risk of mortality reduced by 30% compared to those who downstream with sparing (less than 500 mg per day). Red fruits, garlic, onions, artichokes, cabbages and parsley must henceforth occupy an important place in our diet. Let's swish salt for spices (cinnamon, turmeric, caraway and clove) to keep our blood pressure low and boost our antioxidant intake. Simple gestures to combine pleasure and health. Ad vitamin aeternam?
* Complete PhysioTest at the Thermes Marins of Saint-Malo, 120 €. Information and reservation at 02 99 40 75 00.
THE "WELL-AGING", ISSUE OF THE CENTURY
Several studies presented at the November 2013 neuroscience conference in California confirm the major impact of exercise in preventing aging. Mice trained twelve days in a row have seen their motor functions, their memory and their blood circulation improve. "Sedentariness kills, clearly states Professor François Carré, cardiologist, author of Danger Sedentarity (issue Cherche Midi). Our fellow citizens do not measure how much they put themselves at risk by not practicing a minimum of physical activity. Thirty minutes, even split up during the day, are enough to improve long-term health. So, take your courage with both hands and put on your sneakers!
To be a centenary: for whom?
WHO WANTS TO CELEBRATE 100 YEARS?
Contrary to popular belief, just over half of Europeans want to live beyond 100 years, according to a survey conducted by Ifop in April 2011 for the PiLeJe laboratory. Aspirations vary greatly from north to south: in Germany, despite good economic conditions, 56% of people say they are resistant to such a long life. In the United Kingdom and France, the answers are mixed: 52% are opposed (regardless of the age of respondents). Conversely, the majority of Italians and Spaniards (63%) would like to go beyond the century. According to sociologist Anne-Marie Guillemard of ParisSorbonne University, "the fact that these countries have experienced a greater increase in their life expectancy in recent years and that elderly people live there surrounded by their families, probably explains these differences. ".
There seems to be a natural biological "wall" that does not envision life beyond 130 years.
JAPAN: A RECORD LIFE EXPECTANCY!
The land of the Sunrise is renowned for the longevity of its inhabitants. Apart from 2011, the year of the tsunami, it still has the highest life expectancy in the world: 86.4 years for women and 79.9 years for men, against 84.9 and 78.5 respectively in France (and 67 of all genders at the global level). It also has the largest number of centenarians (50,000), including the oldest of humanity, Misao Okawa, almost 116 years old. When questioned, she attributes her astonishing resistance to her traditional frugal diet (rice, fish, vegetables, green tea). A Bolivian, Carmelo Flores Laura, tries to steal the show. According to the records of his village, this farmer would have blown his 123 candles. Amazing in a country where the average life expectancy does not exceed 66 years . But as the man has no more teeth, the only reliable way to determine the age of an adult biologically, the doubt lurks ... The official record is still the French Jeanne Calment, who died, in 1997, more than 122 years old.
