Anti-ageing jabs – they can rejuvenate mice, but will they work on humans?

Senescent cells are an indication of ageing and are now seen as a driving force behind the process

 

At St Jude children’s research hospital in Memphis, Tennessee, an unusual clinical trial is under way that, if successful, could have wider ramifications for the vast field of age-related chronic diseases. At first glance, childhood cancer survivors may seem like an unusual population in which to study ageing, but as Greg Armstrong, principal investigator of St Jude’s Childhood Cancer Survivorship Study, explains, we now know they represent a group of individuals who are ageing unusually quickly.

For while modern chemotherapies and radiotherapies have become increasingly efficient at curing childhood cancers, this comes at a great cost, owing to the corrosive impact of such treatment on these children’s bodies, something that becomes more apparent when they reach middle age.

“Of these children, 85% are going to beat their cancer, but it’s a win at a cost,” says Armstrong. “We know that these kids will have shortened lifespans. They often die young of chronic diseases like heart disease, stroke or secondary cancers which present much earlier. And we discovered about a decade ago that this is because they’re ageing much faster than their chronological age.”

In particular, this is reflected not just in their biology, but in physical frailty. When Kirsten Ness, a physical therapist and clinical epidemiologist at St Jude, assessed a group of childhood cancer survivors aged 24-41, she noted that when it came to heart function, flexibility, respiratory capacity and range of motion, they resembled people decades older. “We showed that at 30, they have physiological frailty that resembles people in their 70s and 80s, and it’s getting worse over time,” says Ness.

The underlying cause of this is senescence, a state in which cells cease to continue dividing as normal, but instead simply linger, refusing to die. Because of this quality, senescent cells have sometimes been described as “zombie cells” and they are now regarded as a driving force and a reflection of ageing. Over the course of a lifetime, our bodies incur increasing amounts of damage which in turn makes many of our cells, distributed throughout our body, more likely to become senescent.

For childhood cancer survivors, it appears that the consequence of undergoing such radical treatments at a young age leaves them with abnormally large populations of senescent cells, which would normally take decades to accrue. Ness explains that this drives loss of function and disease risk, and not only because senescent cells cease to function as they normally would. Senescent cells also generate a stream of inflammatory molecules, something known as the senescence-associated secretory phenotype (SASP). “If we look at data from our childhood cancer survivors, we can see that they have this low-grade inflammation,” says Ness. “And so they don’t feel great, they don’t move great.”

Over the past decade, interest has steadily grown in a class of drugs known as senolytics, so called because they have been shown to be capable of eliminating senescent cells in mice by disabling certain pathways, causing them to self-destruct. One of the most well-studied senolytics is actually a chemotherapy drug called dasatinib, while others include the natural chemicals quercetin and fisetin, which are found in various fruits and vegetables.

 

Resource: theguardian.com/science/2025/feb/08/anti-ageing-jabs-they-can-rejuvenate-mice-but-will-they-work-on-humans?utm_source=chatgpt.com