link To protect the body, aged cells undergo the ultimate sacrifice: they switch on molecular machinery that results in their own death—a process beautifully named “apoptosis,” meaning the “gentle falling of leaves” in ancient Greek. But sometimes aged cells go rogue. Rather than committing suicide, these cells lurk in our hearts, livers, kidneys and brains, where they silently promote disease. Scientists have long suspected that these “senescent” cells cause us to age, but getting rid of them without harming normal, healthy cells has been challenging. Now, a collaborative effort between the Erasmus University in the Netherlands and the Buck Institute for Research on Aging in California may have a solution. Published in the prestigious journal Cell, the team developed a chemical torpedo that, after injecting into mice, zooms to senescent cells and puts them out of their misery, while leaving healthy cells alone. “This is the first time that somebody has shown that you can get rid of senescent cells without having any obvious side effects,” says Dr. Francis Rodeir at the University of Montreal in Canada, who was not involved in the study. When treated with the drug, aged mice regrew their scraggly fur into luscious coats and saw improved liver and kidney functions. They also seemed more energized, opting to spend their time on a running wheel instead of sleeping in a corner. Rather than a synthetic chemical, the drug is a small peptide made up of amino acids, the building blocks of protein. Similar peptide drugs are already revolutionizing stroke therapy, and the team plans to begin human safety trials with their anti-aging drug soon. The study offers the first glimmer of hope that deleting senescent cells could be feasible in people. “It’s definitely a landmark advance in the field,” says Rodeir. Last year, scientists at the Mayo Clinic in Minnesota genetically modified mice so that their bodies automatically killed off about 50-70 percent of their senescent cells. After six months of treatment, the mice had healthier kidneys, stronger hearts, and—the most jaw-dropping result—they also lived 20 percent longer than the controls. Even the scientists were shocked, remarking that they didn’t expect such a dramatic improvement. The study galvanized the field: senescent cells do in fact contribute to aging. And if they can be stopped, maybe we can also slow down the aging clock. The billion-dollar question was how to make it work in humans, without resorting to gene therapy. Sign me up!