A cure for ageing is near but you probably can't afford it

 作者:鞠伲怀     |      日期:2018-01-17 04:32:11
Aldo Sperber/Picture Tank By Jessica Hamzelou FEEL that? It’s your body, slowly degrading. Ageing affects us all, and it leads to diseases that eventually kill most of us. No wonder so much research is going into creating an antidote. If we come up with a way to slow, halt or even reverse the ageing process, we could potentially protect people from cancer, heart disease and Alzheimer’s. The idea is to extend “health span”, the number of years of good health a person enjoys. Extra birthdays are simply a bonus. Where philosophers once pursued outlandish schemes for eternal youth, researchers now believe there are plenty of worthwhile options to investigate. But do any hold water, and will they be for all, or only the rich? Take the young blood plasma theory, for example. The idea is that there’s something in the blood of people aged under 25 that keeps them youthful, although we don’t yet know what it is. Old mice injected with plasma from young mice, or even from human teenagers, appear rejuvenated – they are healthier, more active and show fewer signs of ageing. There’s also anecdotal evidence that people who get blood transfusions from under-25s feel better than those who receive blood from older donors. Teams around the world have started trials of blood plasma transfusions to treat age-related diseases, but Jesse Karmazin is taking a different approach. His company, Ambrosia, based in Monterey, California, is offering them to anyone – providing they can afford the $8000 price tag. Karmazin hopes to treat 600 people and record their health before and after a transfusion. So far, Ambrosia has signed up 40 people and treated 20 of them. “They’re all over 35, and are in relatively good health,” he says, although some have chronic fatigue syndrome or Alzheimer’s. Most are in their 60s and 70s and have a variety of reasons for wanting to stay young. Not all are rich – some see the experiment as a worthwhile investment. The people who have been treated are already reporting benefits in cognition, muscle strength and energy levels, says Karmazin. But this clearly isn’t a rigorous clinical trial with placebos, so as of yet, we can’t be confident of any benefits. “Old mice that get blood plasma from young mice or from human teenagers appear rejuvenated” Karmazin says it’s ethical to offer the treatment and that it is cheap and safe, meaning it could quickly enter mainstream medicine. He buys the plasma from blood banks, where he says it is often a by-product of blood prepared for transfusion. Others are yet to be convinced, and think other treatments show more promise. They are aiming to enhance DNA protectors known as telomeres, an idea backed by decades of work in mice and other animals. Telomeres are the “caps” on the ends of chromosomes, and plenty of evidence links their length with ageing. The caps shrink every time a cell divides, until they are too short to protect chromosomes from damage. Next comes either a straightforward cell death, or a slow process called senescence that leads to inflammation and surrounding cells being damaged. Both animals and people who start life with short telomeres tend to develop age-related diseases earlier in life, and to have shorter lifespans. Maria Blasco at the Spanish National Cancer Research Centre in Madrid has spent much of her career studying telomeres. A few years ago, Blasco and her colleagues found a way to extend the telomeres of mice using gene therapy. The animals lived 40 per cent longer as a result. This therapy is not yet ready to roll out, as we don’t know if it will work in humans. There are safety issues, too. Some researchers worry that maintaining telomeres could help damaged cells survive, leading to cancer, although Blasco found that her mice seemed to be protected from this. But that hasn’t stopped Liz Parrish from trying the treatment on herself. Parrish, who is not a scientist, launched her company, BioViva, based near Seattle, to explore and test new treatments that target the processes underlying ageing. “We can’t really create preventative medicine if we don’t address biological ageing,” she says. After surveying existing work, Parrish felt that the telomere extension findings were the most convincing. She says she worked with scientists to develop a modified version of Blasco’s gene therapy – the details remain under wraps – which she claims to have had by injection last year. Alongside it, she received another gene therapy to prevent loss of muscle mass, which is thought to be another cause of age-related disease and frailty. Parrish says she wasn’t scared to try the treatment. “My grandmothers had died of Alzheimer’s, and my grandfather died of heart disease. I thought, if I don’t do something, I know what I’m likely to die of.” Parrish says she has felt “fantastic” since the treatment, and that her telomeres have grown by a length equivalent to wiping 20 years off someone’s age. That in no way amounts to a proper trial, of course, so this year, Parrish plans to launch clinical trials of her gene therapy outside the US, in people with various age-related diseases. A few other anti-ageing approaches are also showing promise. Senescent cells that pump out chemicals damaging to their neighbours could be targeted, by either preventing their development or periodically killing them off. One team is probing the use of heavy fats – so named because they contain a heavy isotope of hydrogen – to protect cells from the wear and tear associated with ageing. And others are trialling the diabetes drug metformin (see “A disease staring us in the face?“). Treatments still in development aside, many people already take supplements in the belief they might stave off ageing. Unfortunately, even those with a little evidence in their favour probably aren’t helpful on their own or at the small doses usually taken, says John Ramunas at Stanford University in California. “I’ve tried so many supplements, just because I’m curious,” he says. “But the number one thing that we know can protect your telomeres is exercise.” In fact, there’s a lot we can do to extend our health span without anti-ageing treatments, says Craig Venter, who recently launched Human Longevity Inc (HLI) to offer its customers reams of personalised health data. The most popular package, at $25,000, sequences your genome and microbiome and provides scans, blood tests and more. Venter wants to help people identify which diseases they are likely to develop, or are already developing, while the conditions are still easy enough to prevent or treat. “This is a healthy cohort, but we’re finding that around 40 per cent of them have serious underlying disease,” he says. His own results encouraged him to lose weight. “I’ve lost 43 pounds since finding out things about my metabolic condition.” “My grandmothers died of Alzheimer’s. I thought, if I don’t do something, I know what I’m likely to die of” Venter thinks a full medical assessment and personalised health advice will be more beneficial than any anti-ageing treatment. “I don’t think you need some magic elixir,” he says. But the vast amount of data collection performed by HLI is simply not feasible for many hospitals, and most people won’t be able to afford such health checks. The increased life expectancy in rich countries (see graph) shows that money already buys you more years on earth, so only a low-cost solution will make longevity available to all. Until that arrives, your best options are boring old diet and exercise. Getting old puts you at risk of a host of diseases likely to end your life. But is ageing itself a disease? Some say it can’t be. For a start, ageing is a natural process that happens to even the healthiest. We’ll never be able to eliminate it entirely, and we don’t have clear ways to measure it. Describing it as a disease, which suggests it could potentially be cured, allows us to give in to wishful thinking and unfounded claims for anti-ageing treatments. But Nir Barzilai of the Albert Einstein College of Medicine in New York says that kind of thinking prevents us developing evidence-backed treatments for ageing. His team are running a five-year clinical trial of metformin, a diabetes drug that has been found to boost longevity in a range of animals (Cell Metabolism, doi.org/bvwn). They are measuring the effect of the drug on ageing itself, including general health and cognition, rather than on a specific, age-related condition, in the hopes of convincing the US Food and Drug Administration to recognise ageing as a disease. If they succeed, it could mean this approach makes more sense than thinking about individual age-related diseases. We know that old, worn-out cells put us at risk of Alzheimer’s, cancer and heart disease, for example – why not try to prevent all of them with a single therapy? This article appeared in print under the headline “Time to stop getting old” More on these topics: