Shalizma Khandaker Orni
Another factor that accounts for aging is metabolism. Metabolism enables life itself, but toxic byproducts of respiration, such as reactive oxygen species, can damage and wear down cells. When this damage eventually builds up, it is associated with some the pathology that we see in aging individuals. The damages can be in the form of cellular atrophy, nuclear mutations, mitochondrial mutations and others.
Sophomore
School of Life Sciences
Independent University, Bangladesh
March 23rd, 2019
Aging is a fairly normal physiological process that occurs
in almost all living organisms. It is part of the fundamental cycle of life as
we think of it. However, there are some species in this world that have somehow
avoided this aging process completely. These biologically “immortal” animals,
such as hydras, jellyfish, and possibly some lobsters, pose an interesting
question: could it be possible to eliminate aging? To answer that question, we
have to understand what brings about aging in the first place.
All cells in our body go through cell division, during which
DNA replicates. Due to the nature of DNA replication, every time a chromosome
is replicated, it loses some DNA at the very ends. This is where protective
sequences of DNA called telomeres, come into play. The telomeres at the ends of
chromosomes protect the chromosomal DNA (which harbors functionally important
DNA sequences called genes, among others).
After each successful cell division, the telomeres get shorter and
shorter until they are gone, and the cells stop dividing and are said to become
senescent. These senescent cells can often persist without being replaced,
leading to the tissue degeneration associated with aging, among other outcomes.
Interestingly, stem cells and cancer cells produce an enzyme called telomerase
which can lengthen the telomeres, allowing the cells to continue growing
indefinitely. This enzyme helps lengthen the telomeres, and increased
telomerase activity is associated with cancer.
IMDb
Another factor that accounts for aging is metabolism. Metabolism enables life itself, but toxic byproducts of respiration, such as reactive oxygen species, can damage and wear down cells. When this damage eventually builds up, it is associated with some the pathology that we see in aging individuals. The damages can be in the form of cellular atrophy, nuclear mutations, mitochondrial mutations and others.
Now that we have some understanding regarding the aging
process, we can focus our attention on ways to possibly eliminate it. One idea
that has persisted for a while now is to eliminate the senescent cells that
characterize aging tissue. To that end, researchers at the Mayo Clinic in
Rochester and the Scripps Research Institute in Jupiter, Florida, among other
places, first identified six signaling pathways that various types of senescent
cells rely on to prevent cell death and continue to persist. In early 2015, the
team identified the first senolytic (drugs which kill senescent cells) based on
inhibiting a pathway that senescent cells need for survival. Dasatinib, an
FDA-approved chemotherapy drug, was found to eliminate human fat-cell
progenitors that have turned senescent, while quercetin, a health-food
supplement, was found to target senescent human endothelial cells. Many other
senolytics have since been discovered.. The major difficulty right now is that
these senolytic compounds only target particular cell types. Combination
therapies are currently being considered and investigated.
Another method to prevent aging, that scientists at Harvard
University, among other institutions, are researching have to do with a
molecule called NAD+ (nicotinamide adenine dinucleotide). An important cofactor
in several metabolic pathways for its ability to transfer electrons, NAD+ has been
compared to a fountain of youth. As the body ages, the supply of NAD+ in the
mitochondria diminishes, and this leads to oxidative damage of DNA and other
cellular components by reactive oxygen species. The Harvard scientists are
developing an “anti-aging” pill containing precursors for NAD+ synthesis in
cells. NAD+ has been demonstrated to reverse signs of aging in mice, and a
company called Elysium already sells an NAD+ boosting pill as a supplement,
although they are now going through clinical trials in humans in order to be
able to market it as an actual drug.
One final method (that we will talk about) that scientists
are looking into is the concept of stem cells. Stem cells are the rejuvenating
blocks of life, and have the ability to grow indefinitely and replace other
cell types. Some types of stem cells persist in adults. For instance,
hematopoietic stem cells found in our bone marrow continually replenish our
blood cell populations. As we age, the regenerative ability of stem cells
deteriorates, and the body becomes less capable of repair and recovery.
Scientists are now considering implanting stem cells into aging individuals to
restore their ability to heal or replace old tissue. This has been already been
demonstrated to produce great results in mice, but clinical trials in humans
are still pending.
In conclusion, as technology advances, we are getting closer
and closer to achieving a state of longevity that far exceed any previous human
generations. But the prospect of eliminating aging leaves us with a few
existential questions. Firstly, would elimination of aging lead to an
overwhelming overpopulation that far exceeds the carrying capacity of the
planet? And if so, what measures can be taken in order to prevent that from
happening? Should we even attempt trying to eliminate aging because of the possible
complications that can arise from it? How would this affect culture, religious
beliefs, and society? While there is only a thin chance that this will actually
happen, we should still proceed with caution and awareness.
Shalizma is a sophomore in Biochemistry who wants to be a
researcher and help humanity with my work. She is always open to trying new
things and challenges which help her get out of her comfort zone. In short, she
is just a girl chasing her dreams and having an amazing adventure while doing
it.
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