This popular science piece on the development of senolytic therapies capable of clearing harmful senescent cells from aging tissues is a cut above the average. It is important to see more publicity for this line of work. Not because it will aid the industry, but because the more attention that is given to the field, the faster that existing senolytic treatments such as the dasatinib and quercetin combination will become available through off-label prescription and physician networks. Tens of millions of patients with inflammatory age-related diseases caused in part by senescent cells, and the many cancer survivors with high burdens of senescent cells due to chemotherapy, and diabetics whose condition is mediated by senescent cells, and the obese whose visceral fat tissue spurs cellular senescence might benefit in the US alone, if they only knew that senolytics exist today.
The choice on whether to try now or wait for more human data for dasatinib and quercetin (or fisetin, or piperlongumine, or other easily obtained senolytics) should be one that people are permitted to make, not one they remain ignorant of because nobody bothered to tell them that it exists. My one complaint about the content of this article is that the author does conspicuously fail to mention that it is possible to obtain access to the first senolytic treatments today, at very low cost, and that older people in the self-experimentation community are indeed choosing to do this.
Imagine if instead of a pill you could take to live for ever there was a pill that could push back the ageing process - a medicine that could stave off the frailty, osteoarthritis, memory loss, macular degeneration, and cancers that plague old age. It could happen, with the science of senolytics: an emerging - and highly anticipated - area of anti-ageing medicine. Many of the world's top gerontologists have already demonstrated the possibilities in animals and are now beginning human clinical trials, with promising results. If the studies continue to be as successful as hoped, those who are currently middle-aged could become the first generation of oldies who are youthful for longer - with a little medical help.
Researchers are at work on senolytics, a branch of medicine that targets senescent cells; the various faulty cells that have been identified as instrumental in our eventual demise. These so-called "zombie" cells linger and proliferate as we age, emitting substances that cause inflammation and turn other healthy cells senescent, ultimately leading to tissue damage throughout the body. In 2011 a team showed that "using a genetic trick to get rid of these senescent cells can significantly improve health and lifespan" in prematurely aged mice. In 2016, the same group achieved similar results in naturally aged mice, releasing an arresting image of two elderly rodents born of the same litter. The one cleared of its senolytic cells seems spry and glossy, while its sibling is shrunken, greying and looks its age.
A new company, called Unity Biotechnology, was formed to raise funds to develop medicine that could safely clear zombie cells from the human body. Trials in senolytics are initially targeting specific conditions such as age-related macular degeneration, glaucoma, and chronic obstructive pulmonary disease (which includes emphysema). Most are in the fledgling stages, working on rodents or human tissue in petri dishes, although in February a small early human trial showed an improvement in the distance patients were able to walk. Also this year, a pre-clinical pilot trial for injecting a senolytic drug into the knees of people with osteoarthritis showed promising, if mixed results. It is hoped that, eventually, there will be a number of senolytic drugs that could potentially target different senescent cell types, but currently much of the research has involved a combination of a leukaemia drug called dasatinib and quercetin, a polyphenol common in plants.
Senolytics are particularly exciting because "they seem to still work very late in life. So it will be possible to study more quickly whether they actually work in humans, and they are applicable to people already at the end of their lives." In theory at least, it should prove impossible to build up a resistance to the drugs, "because senescent cells cannot proliferate". Even more importantly, there is significant data to show "that you don't have to treat these patients every single day. You just treat them once a week or once a month. Intermittent treatment is more than enough to have huge benefits." These aren't the only potential added benefits. Senescent cells "play a big role after cancer treatment", developing as a result of chemotherapy and radiation therapy. "If senolytics can be used to help eliminate the damaged cells before they can spread, a detrimental side-effect of cancer treatment could be alleviated."