Longevity 101: Aging & Rejuvenation Research

Longevity 101: Aging & Rejuvenation Research

What you’ll learn from this blog post:

  • What rejuvenation is and what it is not
  • Why treating aging could mean more healthy years of life
  • Which technologies could change how we age in the future

Some people call it life extension, anti-aging, longevity research, geroscience, or even biomedical gerontology, but what does that really mean?

We will simply call it rejuvenation, which is what it is. Join us as we explore how scientists are developing drugs and therapies that target aging itself.

What rejuvenation is

In a nutshell, rejuvenation is regenerative medicine for aging. Our field is a multidisciplinary one and includes tissue engineering, stem cell therapeutics, gene therapy, pharmacology, regenerative medicine, and many others.

Ultimately the goal of our field is the prevention, delay, or even reversal of age-related diseases. It aims to achieve this by making us biologically younger by directly targeting the aging processes as well as slowing down the rate at which we age.

There are nine proposed reasons we age:

  • Genomic instability – DNA damage that mutates cells potentially leading to cancer.
  • Telomere attrition – The caps on our chromosomes wear down leading to loss of tissue regeneration.
  • Epigenetic alterations – Changes to gene expression that harms healthy cellular function.
  • Loss of proteostasis – Loss of efficient protein production leading to accumulated cellular waste.
  • Deregulated nutrient sensing – Failure of metabolism leading to decline of energy production, cell growth, and other crucial cell functions.
  • Mitochondrial dysfunction – Free radicals damage our mitochondria leading to loss of energy production.
  • Cellular senescence – An accumulation of worn out damaged cells which lead to chronic inflammation and loss of tissue regeneration.
  • Stem cell exhaustion – A decline in the ability of our stem cells to replenish damaged tissues by sending replacement cells.
  • Altered intercellular communication – Changes to cell-to-cell communication which leads to chronic inflammation and dysfunctional cell behavior.

These aging processes cause damage to our bodies which ultimately leads to the onset of age-related diseases. Rejuvenation seeks to prevent age-related diseases by repairing the damage caused by these processes and by slowing down the rate at which this damage occurs.

Of course if we can find solutions to these nine processes (spoiler alert: science has!), a happy side effect of this would likely be more healthy years of life, not a bad thing in our opinion!

What rejuvenation isn’t

Hopefully, you will agree that healthy longevity is a positive thing, but before we continue, we need to talk. There is a common misconception about rejuvenation which we need to clear up.

What rejuvenation is not doing is “curing death”. Even if it succeeds in bringing the aging process under medical control, death isn’t going anywhere anytime soon. Keeping people biologically younger would have huge ramifications for health and most likely life expectancies but that is in no way the same as ending death or making people immortal.

So why mention this? Because quite often people conflate the defeat of aging with the defeat of death and it gives entirely the wrong impression of our field. Make no mistake, what our field is working on is medicine. Sure, it is a new approach to treating diseases and age-related ill health, but it is still medicine and grounded in science.

Is rejuvenation even possible?

Thankfully this is no longer really a question from a scientific perspective. Believe it or not, but researchers have known for many decades that it is possible to increase the healthy lifespan of many species.

Yeast, flatworms, fruit flies, rats, and mice have all had their lifespans increased confirming that aging is not a one-way street but is a malleable process. In fact, it is so easy to reliably increase the lifespans of some model animals with interventions it is considered unremarkable by many researchers.

One of the earliest examples of rejuvenation was in 1998 with the C. elegans worm. Researchers discovered that a gene mutation in some worms increased autophagy, a recycling and waste disposal system in cells, which allowed the worms to live a impressive 110% longer. If that was translated directly to humans it would mean living healthily to 168 years old!

This experiment led to a flurry of research focusing on autophagy and its potential to increase healthy lifespan. One of the most reliable ways to trigger autophagy was found to be caloric restriction. This approach involves a reduction of calorie intake below normal, but without malnutrition or a loss of essential nutrients.

This reduction of calories triggers cells to switch to a pro-survival mode and start various austerity measures. One of those measures is autophagy and its activity increases during periods of nutrient shortage to recycle unwanted cellular components and help keep the cell alive.

Caloric restriction appears to extend lifespan in yeast, worms, fish, dogs, mice, and hamsters. The effect of caloric restriction on human lifespan is currently unknown, though some studies do suggest it has potential as a longevity therapy.

More ways to longevity than going hungry

Besides caloric restriction, researchers have discovered other genetic pathways that can influence aging and promote longevity. For example, a study showed that by restoring the telomeres (the caps at the ends of DNA chromosome strands) in mice increases their lifespan by up to 24%.

Reducing insulin signaling was also shown to increase the lifespan of mice by 18%. And the overexpression of sirtuins, a family of genes associated with longevity, also led to a significant increase in lifespan.

Rapamycin, a drug originally used as an immunosuppressant, has increased lifespan in fruit flies, worms, and aged mice. There are many more examples of how lifespan can be increased but hopefully this gives you a taste of what has already been done.

The challenge now and the stage the field is at currently is translating the results seen in animal studies to humans. A decade or two ago the question was: Can it be done? Now the question has changed to: How can we translate it to people?

So now you understand a little more about what aging is and what rejuvenation is and is not, it’s time to take things to the next level. Over the next few articles, we will take a look at some near, mid, and longer-term technologies that focus on aging that could potentially bring us healthy longevity.

To explore available longevity treatments, click here.