THE PROBLEM (1/2)

Stem Cell Aging Causes Our Deaths

Over time, the functionality of the human body’s cells deteriorates and eventually is unable to replicate. Question is, why?

Fatimah Hussain
5 min readJul 16, 2021

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For centuries, aging was the natural way of life. Students were introduced to the concept of aging in their first biology class. We’d even see aging with our own eyes, everywhere we go. We’ve seen it at family dinner parties and with our relatives. Siblings, parents, grandparents, and great-grandparents.

The concept of aging is nothing new to us. It’s a natural process that occurs when our body’s functions change, originating from the cells in our body.

But biological aging is no longer an unsolvable problem.

Aging & Longevity

Although aging is unavoidable, its course can be influenced by various factors. Longevity has also been altered experimentally in some animal species. Aging follows a period of growth and reproduction.

Credit

It’s important to note, however, that aging and longevity are different.

Distinguishing human biological aging from longevity can be difficult due to the fact that the rate of aging may affect the length of the life span.

Longevity can be genetically altered, and isn’t necessarily solely dependent on nature and how the body naturally functions.

Hallmarks of Aging

The following hallmarks of aging are:

  • Stem cell exhaustion
  • Altered intercellular communication
  • Genomic instability
  • Mitochondrial dysfunction
  • Telomere attrition
  • Epigenetic alterations
  • and more…

I’m going on a limb here and going to assume that you don’t know most of these terms, much less what they infer. But the first one, stem cell exhaustion, well encompasses the idea.

What is Stem Cell Exhaustion?

Simply put, the exhaustion of stem cells. The meaning of exhaustion is the decline. Stem cell exhaustion is the decline in stem cells and function, in turn leading to stem cell aging

But to define stem cell exhaustion, it’s prime to understand stem cells.

Stem cells are cells that can proliferate (divide) into other types of cells. For example, hematopoietic stem cells are a type of adult stem cell found in the bone marrow. They make new red blood cells, white blood cells, and other types of I’ve debriefed this type of stem cell in the following article below:

Stem cell exhaustion is caused by telomere attrition, DNA damage, and mitochondrial dysfunction.

Telomere Attrition

Telomere attrition is the loss of caps on chromosomes, which is DNA located inside the nucleus tightly wrapped in a X-shape. Telomeres are structures on the chromosome ends. The job of telomeres is to protect the information that’s contained in the chromosomal DNA. Another role they play is to protect the ends of the chromosomes from fusing with nearby chromosomes.

Depiction of telomere attrition

The telomere caps become slightly shorter each time a chromosome replicates itself. When the cell has replicated so much, the telomere caps eventually is nonexistent.

But this can be prevented by telomerase. Telomerase is a key enzyme for cell survival that prevents the shortening of telomeres and damage to the chromosomal DNA. Telomerase does so by adding additional telomere sequences (TTAGGG, usually repeated 3,000 times) to the ends of your chromosomes. However, most cell types in your body don’t have telomerase or become inactive as you age.

Telomerase also decreases the risk of some diseases but increases the risk of some cancers.

When telomere attrition occurs, it limits cell division and causes mitochondrial dysfunction, which will be covered later. It also enforces the loss of quiescence proliferation.

Quiescence is a temporary cell cycle state where populations of cells rest and do not replicate before they are activated and re-enter the cell cycle.

Quiescence is important because it provides time for DNA repair and prevents the propagation of damage to future generations.

Mitochondrial Dysfunction

Mitochondria are known as the powerhouse of the cell. Mitochondrion generate ATP, an energy-carrying molecule found in the cells of all living things. The mitochondria use ATP to fuel the cell’s reactions. Mitochondrial dysfunction can be caused by senescence, by a disease, or condition.

Mitochondria

Senescence is the no. 1 cause of aging in mammals and is caused by the shortening and degradation of telomeres over time. Each time a cell divides, they lose a tiny bit of DNA at the ends, but telomeres refute that. And as you know, the telomere shrinks after each division. Senescent cells occur when the telomeres are gone, and harm tissue around them, and are linked to diseases such as diabetes.

Cell senescence

A cell is able to replicate approximately 50 times before it becomes senescent.

Mitochondrial dysfunction also negatively affects the cell. Mitochondria fuels all the processes in the cell, similar to a battery. But if there is a problem with the mitochondria, it won’t be able to do its job well, or at all. As a result, the cells will bring a large impact to the body that it’s in. Some include poor growth, visual / hearing problems, and aging.

How Do These Contribute to Stem Cell Exhaustion?

As stem cells age, their functional ability also deteriorates. Their ability to differentiate into the various cell types is altered. So, they aren’t able to provide as well as they did when they were fully functional or before they started proliferating. Accordingly, research has shown that the result of stem cell aging plays a key role in various aging-associated disorders.

Subsequently, factors like telomere attrition, mitochondrial dysfunction, and DNA damage play a large role in the digressing health of these stem cells. The following factors correlate to stem cell aging, therefore contributing to stem cell exhaustion.

The Solution

Healthcare has come far too long for professionals to not find potential solutions to stem cell exhaustion. But, this article has also been far too long, so part 2, creative solutions to mitigate stem cell exhaustion, will come soon.

Personal Note

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Fatimah Hussain

An AI+ML+CAD Software Design Enthusiast. Striving to Create an Everlasting Impact.