Tag: longevity

What is Cellular Senescence

Where do senescent cells come from, and why does our body create them?

As over time and as you get older, you accumulate DNA damage in your cells.

DNA damage can happen in a number of different ways, such as radiation and environmental factors, but can also happen naturally through normal cell growth and division.

This DNA damage accumulates and causes what’s known as senescent cells. Senescence means that the cells are old and have undergone aging at the cellular level.

But some cells don’t experience senescence and seem to be able to undergo healthy division almost indefinitely.

Let’s examine the differences between cells that experience senescence and those that don’t.

Somatic Cells: telomere shortening and cell division

In human bodies, our cells divide 2 trillion times per day.. that’s 2,000,000,000,000. [4]

As somatic cells divide, the caps at the end of our cells (called telomeres) slowly lose information after each subsequent cell division.

source: Khan Academy YouTube Channel [3]

When telomeres become too short, the cells stops dividing.

Telomere shortening and other types of DNA damage results in these cells becoming senescent – which means they autonomously stop dividing.

Doing so helps prevent DNA damage from continuing to happen, and being carried over into future child cells. [3]

Our somatic cells can divide between 60-70 times before the telomeres get too short (called the Hayflick limit).

Stem cells: telomerase and DNA repair

Although somatic cells undergo this natural progression towards cellular senescence after a certain number of divisions, not all cells in the body go through these stages.

Stem cells are special – they don’t experience cellular senscence.

Stem cells are able to maintain their mitotic capacity (ability to divide) and avoid senescence because they have a special enzyme called telomerase.

Telomerase helps cells “stay young” and avoid the Hayflick limit because it is able to rejuvenate the lost ends of telomeres after dividing. [4]

Humans have stem cells in all different types of tissue and organs throughout our bodies.

Why don’t somatic cells produce telomerase?

In regular cell function, telomerase is specific to stem cells, and somatic cells are not supposed to produce telomerase.

However, because our body creates 100 billion new cells every single day, mutations can happen where a somatic cell will produce telomerase. This is actually a BAD mutation!

And while telomerase might sound like the key to keep our cells young, unfortunately, its more complicated than that.

Telomerase production in somatic cells results in uncontrollable cell division and growth, which causes cancer.

Even at an extremely low rate of mutation, the high number of cells means more opportunities for cancer to form.

Problems caused by senescent cells

Similar to brain neurons and heart muscle cells, senescent cells don’t divide. They shut down and stop copying DNA and dividing.

Somatic cells undergo senescence to stop dividing and to avoid becoming cancerous. And as humans age, we have more senescent cells in our bodies.

Although good for the prevention of cancer, too many senescent cells is a detriment to human health.

Senescent cells secrete proteins and molecules that cause inflammation. (senescence associated secretory phenotype, or SASP).

Remember, inflammation is BAD. Due to the SASP factors from senescent cells increasing inflammation in our bodies, we experience debilitation and disease at increased rates.

So although we want our somatic cells to avoid growing uncontrollably and causing cancer, we also want to avoid the presence of senescent cells if at all possible.

The future of cellular aging

Scientists are looking into ways to remove senescent cells to improve health. Senolytic drugs, for example, are built to kill these cells.

How do you think the future of cellular aging will look?

Tweet @espressoinsight and let us know what ideas you have.

Sources:

  1. The Hallmarks of Aging https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836174/
  2. SENS Overview of Cell Senescence https://www.sens.org/overview-of-cell-senescence/
  3. Telomeres and cellular senescence https://www.youtube.com/watch?v=R5YiO6rKr-w
  4. Cell division https://askabiologist.asu.edu/cell-division#:~:text=Organisms%20grow%20because%20cells%20are,trillion%20cells%20divide%20every%20day.

Why Humans Need to Cure Aging

During a conversation with a friend, the topic of longevity research came up, which I expressed my longstanding support for.

My friend came back expressing his idea that death is actually important, and questions of why we shouldn’t die, concerned about how life will be special if we don’t die.

The argument of whether or not we should extend longevity has and will be continued to be had over and over and over again. The points and arguments may be disagreed upon, but it is important to lay them out in writing once and for all:

First of all, we should be so lucky to be able to worry about living forever.

At this stage, we aren’t even sure if curing aging is possible.

We’re pretty far from discovering the cure for aging.

The proclamation that “we shouldn’t cure aging” is silly if we don’t even know for sure that it is possible.

What we do know is that people suffer unnecessarily due to age related illnesses.

While some of us with longevity genes live healthy and active well into our 90s, many of our loved ones get older and face cancer, obesity, dementia and alzeimers, and more.

The issue is that these debilitating aging illnesses consume a large number of years towards the end of a persons life.

By solving aging, first and foremost we must allow people to live healthy, active lives up until the end.

Its unlikely we’ll be able to extend life indefinitely (at least as far as we know).

But what if humans could live healthy lives into their twelfth decade, reaching 120+ years of age?

I believe this is absolutely possible and achievable at the current pace of scientific research.

We want to find a way to end diseases. No one is saying you have to live forever.

You can still die. But wouldn’t it be great to extend our lives a little longer?

Why is extending human lifespan important?

As a person finishes school and gets their start in the “real world”, their lives are likely already 1/3 to 1/4 of the way over.

As disappointing as this may be, it is a fact – and the sooner you come to terms with mortality, the easier it will be to focus and commit to the truly important things in life – that which gives your life meaning, whatever that may be for you as an individual.

Reason #1 – more productive years for skilled professionals

Take an example of the career of a doctor.

If you decide to become a doctor, you’re going to have to spend another 8-ish years in school on top of college.

By the time you make it out of medical school and residency as a practicing physician, if you’re lucky, you will be about 30 years old.

On the other hand, many students don’t get into medical school the first time around due to grades, preparedness, slow decision making, and other reasons. Its not uncommon to see medical students enter their M1 year of school after taking a 3-4 year gap between undergrad and medical school.

Because of this, a career doctor can expect to spend between 30-35 years as a practicing physician, assuming an average retirement age of 65.

There is a shortage of primary care physicians globally, and a shortage of specialists in the US.

Its too bad that after all that school and training, one of the most valuable professions in our society gets so few years of productive work out in the real world.

The skills that a doctor possesses are important and benefit society. Becoming a doctor is no easy task. Wouldn’t it be better if a doctor was able to practice medicine for more years, allowing society to benefit more from their hard earned skillset?

How much better would surgeons be if they were able to put that much more time under their belt? Why can’t people live to be 200, 500, or even 1000 years old?

The same can be said of other skilled professions as well. How much would human society benefit from having elders with decades upon centuries of experience to help us run our seemingly broken society?

It is unfortunate that humans have to have this upper-limit to their age of productivity.

As soon as you really start to get your life figured out – by the time you get your finances under control, have learned quite a lot about the world, have developed a strong network of friendships, and built a solid career, the effects of aging start to creep up on you and slowly compound and get worse over the next several decades of life.

Reason #2 – aging is expensive

As you reach old age, the numeric age of a person is quite insignificant.

What really matters is the quality of life, health, and prevalence of disease – or ideally lack thereof.

But one thing is for sure – as people get older, they tend to develop more age related illnesses.

These illnesses unfortunately cost a lot.

Medicare in the United States spends about $35 billion per year on kidney failure alone. [1]

At age 65 and older people spend over $11,000 on average per year on healthcare.

Imagine a futuristic society where people don’t have to get sick and debilitated as they get old.

Imagine that instead of spending $35 billion on treating kidney failure (which, by the way, is almost always incurable), we spent far less money on re-programming cells and turn back the aging clock.

The large healthcare costs could be more efficiently put towards other endeavors such as infrastructure, education, providing clean access to drinking water, advancing space travel – anything we can think of to make life more enjoyable for everyone on planet Earth.

Reason #3 – death is scary

No matter what they say, no one wants to die.

Yet, when bringing up the idea of living forever, so many people start acting squirrely and say something along the line of “but without death, we won’t have meaning in our lives”.

The thing is, we’ll always die. But the goal here is to stop the body from breaking down.

Let’s not worry so much about they unknown negative effects of living forever, and instead, let’s first focus on finding a cure for aging and age related diseases, enabling people to live healthy lifespans for longer.

A special thank you to David Sinclair and his inspiring book “Lifespan”.

  1. Kidney Project Statistics

Stanford is Helping Humans Age Well

Everyone wants to thrive during old age. What will it take to to increase the number of years of healthy, active life that we all have the opportunity to experience? Stanford University created a center to do just that.

The official mission…

…of the Stanford Center on Longevity is: “accelerate and implement scientific discoveries, technological advances, behavioral practices, and social norms so that century long lives are healthy and rewarding.” The center has three divisions: Mind, Mobility, and Financial Security.

From the mission above, let’s look at what, specifically, Stanford is doing to help us achieve healthy, rewarding, Century-Long Lives.

In an internet-connected world…

…more and more devices are starting to track human data. In addition to devices such as fitbit heart rate and step trackers, our iPhones also have the capability of collecting and recording large amounts of data from our everyday lives. Aggregating this data and analyzing it using Artificial Intelligence algorithms could provide insight into a person’s current state of health, which may allow for earlier prediction of disease, to recognize it in its early stages. For example, according to the New York Times, speech recognition software has been used by Arizona State University to analyze linguistic data of NFL players at press conferences over a multiple year period to determine changes in vocabulary and sentence structure, which provided insight into the onset of chronic traumatic encephalopathy (CTE). What if a similar speech analysis technology could be applied during phone calls of individuals with Parkinson’s disease so that their doctor can adjust the medication, as this article from Slate mentions? What if one could apply the same for Alzheimer’s? Complex algorithms would have to be written, but when considering the scope of technological capacity that we have today, this is certainly possible.

Financial Stability

The center is helping people with achieve and maintain financial stability. Some great first steps to becoming more financially stable include getting out of high-interest debt (such as credit card debt), paying off student loans/mortgage each month, living below your means by creating a budget, saving a regular percentage of your income, maintaining 6-12 months of living expenses in cash, and finally, investing. From a financial standpoint, center focuses on financial capability, new career lifecycles, and common financial pitfalls (such as fraud). In order to maintain your finances as you get older and well into your retirement, the center covers some best practices and other wisdom related to helping manage retirement income, and even ways to supplement that income. If we’re going to be healthier and energetic for longer, humans will have the opportunity to start a side gig, take up a craft, and maybe even build their own business.

Fellowship

Surrounding yourself with a supportive community is supremely important as well. William Chopik mentions that, whether it be friends or family, “having people you can rely on, for the good times as well as the bad” may be so crucial to keeping stress levels low and maintaining positivity, and overall happiness.

It’s great to see universities like Stanford leading our civilization on teaching and spreading the word about how we can implement some of the latest breakthroughs in longevity research. The center’s website will serve as a great resource to help people take small actions to maintain health.

From the Stanford Center on Longevity’s website, it was founded in 2007 by Thomas Rando MD, PhD, and Laura Carstensen PhD.