Why do we age?

There are species in the animal kingdom that do not age, undying creatures. Can we become one of them?


Reduced capacity for rejuvenation and the accumulation of cell waste.


Aging is a complicated and pervasive process. It is the result of our body’s limited capacity to regenerate itself. The greatest risk factor for human diseases in the developed world is aging. Currently, there’s roughly 150,000 people dying each day – two thirds of those from age-related diseases. Here, I will address three components of aging that are of particular interest to scientists due to their intimate connection with the aging process: NAD+, cellular senescence and stem cells.

Our bodies are made up of tens of trillions of cells, and our cells are made up of hundreds of millions of parts. They constantly work together in a beautiful harmony, and the emergent property results in our internal reactions, our organs and our body. The parts that make up our cells constantly needs to be removed, replaced, and rebuilt. As we age, this process becomes less efficient, resulting in the parts being damaged, removed slower, or no longer produced in the quantities we need. One of these parts is NAD+, a coenzyme that maintains the efficacy of this process. The levels of NAD+ present in our bodies, diminishes over time as we age. Low amounts of NAD+ are linked to several diseases from skin cancer to Alzheimer’s, cardiovascular disease, and multiple sclerosis. In theory, if we can maintain the optimal levels of NAD+ in our bodies as we age, we might see a slowing down or maybe even reversal of the more common age-related diseases. Restoring the levels of NAD+ in old mice, have been demonstrated to promote health and extend lifespan. This molecule however, cannot diffuse through cell membranes, and so we cannot ingest it by way of pills. Thus, we need to circumvent this issue through the use of NAD+ precursors. Scientists noticed that more flexible substances could enter cells and turn into NAD+ inside. Ongoing research into the effectiveness of such precursors have just recently begun.

Another component to aging is the build of senescent cells. Over the course of our lives, our cells continually divides and copies its chromosomes. Each day, nearly 2 trillion cells divide. Because of how cell division works, they lose a small amount of DNA at the ends of their chromosomes. To protect themselves from this, additional long segments of DNA called telomeres are wrapped around the ends of the chromosomes.

After each cell division, the telomeres at the tips of the chromosomes become shorter and shorter. In some cells, this continues up to a point where the telomeres are entirely gone and they become senescent. SOURCE: ISTOCK AT https://www.istockphoto.com

In some cells, after a number of cell divisions, the telomeres will be entirely gone and the cells become senescent. These senescent cells accumulate in our bodies throughout our lives, and unlike normal cells that may undergo programmed cell death (apoptosis) when they are damaged, senescent cells don’t. This becomes a problem as senescent cells harm tissue around them and are linked to many diseases that are age-related like diabetes and kidney failure. The inception of the CRISPR/Cas9 technology, enabling specific genome changes in living organisms, may prove to be a powerful tool for researchers trying to understand the dynamics of telomere formation, as well as telomerase activity.

Lastly, there’s stem cells. Stem cells are present throughout the body and remain in a non-specific state until they’re needed (e.g. for tissue repair). Unfortunately, stem cells in our bodies decline as we age, ultimately leading to our own decline as well. Without stem cells to renew tissue and help the body maintain its proper functionality, we become increasingly worn out, unable to replenish ourselves.

Embryonic stem cell illustration.
SOURCE: www.istockphotos.com

The decline of NAD+ and stem cells, as well as the build-up of senescent cells harming the cells around them, are major components causing us to age. In the following posts, I will go into more detail on each component and how they can be engineered and/or manipulated to help us fight aging and its devastating consequences. Aging gradually diminishes your quality of life, and in the end causes a significant burden to your loved ones and to our society. There is a rising issue of there being more people of old age than there are people being born. In most countries, there’s not enough resources to provide care for all the elderly. There’s also increasingly more cases of neglect among their caretakers, as it is a very straining job and they’re all too often undermanned.

If you’ve ever experienced a loved one on the verge of loosing their hearing, their vision or their minds — unable to take care of themselves — you might agree that we should do more to prevent this.

Imagine what the future holds.

Don’t miss out on it.

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2 thoughts on “Why do we age?

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