Health is the most precious possession we have in life, but we often seem to be oblivious about that until we lose it. Humans are living longer lives compared in the past, and that is great, but an unpredicted result of this is that we also spend bigger and bigger portion of our lives being sick. Being old right now is the same as spending more time in pain. So researchers are starting to shift the focus of the medical community's resources from maximizing lifespans to maximizing healthspans, the part of our lives during which we are healthy.
To achieve this, we need to fight the primary cause of almost every bodily defects, Aging. Unknown to most people, the battle againsts aging has made tremendous progress in the past several years and immenent human trials soon.
Let's explore the three examples of discoveries that can benefit humans who are living right now.
Senescent cells
Our cells have an expiration date. Everytime one of our cells divides, it copies its chromosomes. Because of how the way this happen, they lose a tiny part of themselves at the ends. This can be destructive, so to protect themselves we have long sequence of DNA called telomeres at the ends that act like the rigid ends shoelaces, the aglet(ya that's how it's called), but they get smaller after each cell division cycle. In few cells, after a number of cell divisions the telomeres are expended, and the cell becomes a "walking dead", a zombie, a senescent cell. Senescent cells stay around and refuse to die. The older you are, the more of them are within you. They harm tissues around them and are relatrd to many diseases that comes with old age like diabetes and organ failure. But what if you could kill them off?
Scientists conducted an experiment that genetically engineered mice so that they can destroy their senescent cells as they pleased. Older mice without senescent cells were more active. Their hearts and kidneys worked better, and they were less prone to cancer. As a result, they lived up to 30 percent longer and in better shape than an average mice. Since it is impossible to genetically engineer all of our cells in the body, we need to find a different way to get rid of our senescent cells. But how can we kill them off without harming the healthy cells?
Most cells in the human body initiate a programmed cell suicide when they are damaged but senescent cells don't. It is found that they underproduce a certain protein that signals them when it is time to die. So in a late 2016 study, mice were given an injection of this protein. It killed 80 % of all their senescent cells, while causing almost no harm to healthy cells. The treated mice became generally healthier and even regrew lost hair. As a result, there are a number of new companies looking at treatments involving senescent cells and the first human trials will start soon.
NAD+ (Nicotinamide adenine dinucleotide)
Cells are made of hundreds of millions of interconnected parts. They are the buildings, machines, messages, and the catalysts that make reactions happen. All those parts constantly need to be destroyed, cleaned up, and recreated. As we become older, this process becomes more inefficient and so parts become weaker, bunched up, or are removed, slower, or they no longer produced in the quantities we need. One of these parts is NAD+, a coenzyme that tells ourselves to look after themselves. At age 50, we only have about half as much in our bodies as we do at age 20. Low amounts of it are linked to a whole bunch of diseases from skin cancer to Alzheimer's, cardiovascular disease, and multiple sclerosis. But NAD+ can't enter cells so we can't get it as drug. But scientists notice that other more flexible substances could enter cells and would then turn into an NAD+ inside.
In 2016, multiple trials on mice showed that they boosted the multiplication of skin, brain, and muscle stem cells. They were rejuvenated, had a higher ability to repair their DNA, and had a slightly increased lifespan, This even got NASA interested, which is looking for a way to minimize the DNA damage astronauts would be exposed to from cosmic radiation on Mars missions. There are human trials being planned right now, but it's too soon to say if this will boost our healthspan or even lifespan. But NAD+ is a serious candidate and could become the first human anti-aging pill.
Stem Cells
Stem cells are sort of cell blueprints that are at various places in our body and duplicate themselves to produce a constant flow of fresh new cells, but they decline as we get older and so we decline too. Without new parts, human bodies get weaker. In mice, scientists found that as the stem cells in their brains disappeared, they started to develop diseases. So they took stem cells from baby mice brains and injected them directly into the brains of middle-aged mice, more specifically the hypothalamus, a part that's involved in regulating a lot of bodily functions. The fresh stem cells rejuvenated older brain cells by secreting micro RNAs that regulated their metabolism. After 4 months, brain and muscles worked better than those of untreated mice and on average, they lived ten percent longer.
Another study took stem cells from mice embryos and injected them directly into the hearts of older mice. As a consequence, they had improved heart function, could exercise 20% longer, and weirdly enough their hair regrew faster.
Conclusion
What all of this tells us is that there is not a single magic weapon with which to cure aging. It requires a complex array of different therapies. We can kill off senescent cells to clear away the junk, give ourselves fresh new stem cells to fill the gap, all while regulating the metabolism of the other cells using medication. This video comes with a big caveat. After all, these studies have been carried out on mice. There's no guarantee the same therapies would work in us to the same extent, but they are proof of concepts. To learn more about how we can modify our own healthspan, we need human trials. We've only covered a tiny part of the research that's being done right now, and only scratched the surface of these ideas. The field of healthspan extension needs more attention and funding. If it gets it, all of us might enjoy growing old without pain