Over the past decade, the quest to extend human life and make it healthier in recent years has found a new hero: senolytic drugs. These drugs have the potential to eradicate damaged cells that build up in our bodies as we age, stopping the diseases associated with this process, from Alzheimer's to cancer.
Until recently, however, no senolytic drug was accurate enough: surely the developed ones attacked the "bad" cells, but probably also affected the good ones.
Make way for the second generation
Last month, scientists from the Universities of Cambridge and Leicester designed a type of antibody that can attach to specific proteins outside cells (I told you about it here). This leaves very little chance of side effects. Each "senolytic" antibody is essentially a protein-seeking missile loaded with toxins. It settles in, "and once inside, it explodes," he says Salvador Macip, the lead researcher of the team. "That's why we call it a smart bomb."
Since this advance (last month, I repeat) a test on humans has not yet been developed, nor on animals. Macip's research, however, brings medicine closer to addressing what appears to be the main cause of age-related conditions. Although it is unlikely that we will ever be able to defeat death, this senolytic approach could help us lengthen it (even a lot) and end it with our mind and body still in efficiency.
A few words about senescent cells
Cells age. They get hurt and stop producing other cells. This is what we call senescence. This helps them stay healthy and prevents bad things like cancer from happening: but even though the senescent cells are "dead", they are still active in another sense. Scientists often compare them to zombies: dead but dangerous. They continue to emit chemicals that cause inflammation and can kill other cells as well. When our immune system works well, it kills these bad cells before they do any more damage. Sometimes, however, the immune system no longer works so well: this is why experts believe that this proliferation of senescent cells is responsible for many of the diseases of old age.
Scientists, in summary, have found that when a senolytic is used to treat certain diseases, it can make them go away. And not just: already in the 2011 Mayo Clinic researchers in the US treated cataracts, muscle degeneration and fat loss using first generation senolytics. What will we see with the second generation ones?
A senolithic future: what changes in the war on aging
The challenge of designing treatments that will only attack the right cells has not disappeared with the new antibodies. This is because any target that a senolytic might latch onto (in this case, a surface protein) likely exists in healthy cells and throughout the body. To avoid this "friendly fire", Macip suggests future researchers to use two, three or more markers. This way there will be less chance of confusion. Separate antibodies could be designed for each marker and only when all of them are "hooked" will the senolytic do its duty.
However, this will be a problem for the third and fourth generation of these drugs. Macip hopes: "Within the next decade we may see one or more targeted senolithics reach the studies." He and his colleagues aren't the only ones working on this problem: another team of researchers, led by the Cambridge oncologist Daniel Muà ± oz-EspÃn, made the leap last year with a senolytic treatment for cancer which seems to do its duty with more attention than its predecessors.
In search of the perfect senolytic: a roadmap
As the accuracy of this medicine improves, it will be able to help more people. Macip has also drawn up a possible "roadmap" that will lead a senolithic (or more senolithic) to fight against old age. The first treatments should arise against lung diseases and cancer. Alzheimer's disease follows, which kills (but not as fast as pulmonary fibrosis and cancer). Last, but not least, diabetes.
Most of all, the development of an effective senolytic will usher in the next phase of the battle: the one against the common denominator of practically all these diseases, old age. Instead of fighting a disease, in other words, we will fight against the condition that determines it: a complete paradigm shift.
Eternal life? Let's not joke
It is a common misconception that the ultimate goal of anti-aging research is eternal life or the fountain of youth. The truth is that science thinks it can "only" keep people healthy for as long as possible.
Perhaps we will be able to run marathons until our 70s or just stay as active as we were at 50. This is what medical professionals mean by "extending health span." It could lead to a longer lifespan, but the goal is not immortality. "It's not going back in time," Macip says, "but keeping someone healthier, for longer."
