PHILADELPHIA — There’s good news for the millions of people who battle back pain each and every day. An injection that nips backache in the bud has been developed by scientists. It contains a cocktail of anti-aging drugs called senolytics that kill off “zombie cells.”
Chronic back pain affects more than 15 million adults in the U.S., racking up billions in healthcare costs and lost workdays. The injection could protect people against the crippling condition for decades. Clinical trials are already being planned.
In experiments, young and middle-aged mice had less disc degeneration by the time they grew old than peers given a placebo. They also had fewer senescent cells that stop dividing and release chemicals that cause inflammation. They have been dubbed zombie cells because they are damaged, yet refuse to die.
“Once intervertebral discs start to degenerate, there is very little regeneration that happens. But our results show it is possible to mitigate the disc degeneration that happens with aging,” says study lead author Makarand Risbud, a professor of spine research in orthopedic surgery at Thomas Jefferson University, in a statement.
The spinal “cushions” that support vertebrae dry out over the years and don’t absorb shocks as well. Simple daily activities and sports trigger tears in the outer core. Most people over 60 have some deterioration. Few treatments are available. Most patients do not meet the criteria for surgery or steroid injections, which are often ineffective. Prolonged use of strong painkillers, such as opioids, carries the risk of addiction.
Now the team at Jefferson has come up with a novel approach that combines the drugs dasatinib and quercetin, medications that flush out senescent cells. Every tissue in the body collects them over time. They secrete destructive enzymes and proteins that harm healthy cells.
Senolytics leave room for the formation of fresh ones. The researchers say the non-invasive technique paves the way for treating back pain. The two drugs are currently being tested on humans to treat lung scarring. They were also shown to work on discs in the spine but in a surprising way. “Just because the drugs work in one tissue does not mean they will also work in another. Every tissue is different,” Dr. Risbud says.
Weekly injections reduced disc generation, with the best results in middle-aged and young lab rodents rather than their elders. They actually had a protective effect. It was thought that the oldest animals would benefit most as they had more senescent cells.
“We anticipated [that] in tissues with a lot of senescence, removing the senescent cells would make a big difference, but it didn’t. The therapy was most effective when we started treating the mice when those senescent cells were just beginning to emerge. Our findings show if given early, senolytic drugs can actually slow disc degeneration. This is a novel preventive approach,” explained Dr. Risbud.
The animals needed a weekly injection until they reached old age — a much longer period than senolytics have ever been used before. But no side effects were identified during the long-term treatment. “It is possible people will have to take this for a long time for treatment to be effective. Our data show the drugs were well tolerated — at least in mice,” Dr. Risbud said.
The study demonstrates that senolytics already approved for clinical trials can combat age-related disc degeneration. “This research paves the way for translating these studies first to a preclinical animal model and then to a clinical trial in humans,” added Dr. Risbud.
Senolytics have been hailed as a new weapon in the war on aging, potentially treating a range of diseases that plague the elderly. Some scientists reckon they hold the key to eternal life. The ultimate dream is a panacea: a cure-all for the ills of growing old.
The study is published in Nature Communications.
South West News Service writer Mark Waghorn contributed to this report.