Uncovering the Link between Biological Age and Epigenetic Clocks: Are We Nearing a Way to Overcome Death?
More humans are now living longer, healthier lives and organizations in Silicon Valley are devoting billions to discovering methods of stopping and even reversing the effects of ageing. Pharmaceutical and biotechnology firms all over the globe have transferred their endeavours and studies from attempting to avert the danger of instant mortality to prolonging life.
In 2014, Joon Yun, a hedge fund supervisor, gave scientists a $1 million incentive to crack the code of life and extend the human lifespan beyond the estimated 120 years. There is a great deal of interest in living longer and healthier lives.
Epigenetics could be a piece of the puzzle in this pursuit. But what is it? What is meant by a biological clock? How are the two linked?
What is the Study of Epigenetics?
Epigenetics examines alterations in gene expression within organisms which are not caused by modifications to the DNA sequences.
Epigenetic alterations differ from genetic ones since they are not permanent, and the genetic code inside cells remains unchanged. Nevertheless, epigenetics can shape how the DNA is read, altering subsequent responses.
Epigenetic modifications are achieved by attaching certain chemicals to DNA strands without altering the sequence of the nucleotides. This process can either activate or deactivate genes and thus control the production of proteins within the cell. This mechanism allows cells to produce only the proteins required to function correctly.
The entirety of a cell's DNA is referred to as the genome, and all the modifications that affect gene expression are known as the epigenome. Factors such as exercise, nutrition, pressure, drinking, smoking, environment, and socio-economic condition can all affect the epigenome; there is no limit to what may influence it.
Epigenetic modifications can differ from person to person, and some of these changes may persist throughout the individual's life. However, many unknowns exist surrounding why modifications may vary with age.
Epigenetic Aging's Trigger is Unlocked by DNA Methylation
Epigenetic modification through DNA methylation is a significant component of many cellular activities, such as gene suppression, chromosome stability, embryonic development, genomic imprinting, and chromosome inactivation.
It has been discovered that when the DNA methylation process malfunctions, it can be correlated to certain medical conditions, including cancers, cardiovascular diseases, atherosclerosis, and nervous disorders.
Research conducted at the University of California, Los Angeles, by Professor Steve Horvath revealed that methylation could effectively measure biological age. To come to this conclusion, the team examined 13,000 human samples and formulated an algorithm to determine a person's biological age accurately.
In 2013, Horvath created his renowned Horvath clock, which is utilized extensively. This idea, and other similar ones, are based on revealing how much organs have deteriorated. This could then help anticipate how many years of life a person has left, despite much disagreement regarding the precision of these clocks.
Horvath has dubbed his clock a "pan-tissue clock" due to its ability to accurately assess the age of many organs in the human body. To create this clock, methylation data was collected from 8,000 samples of more than 50 different cell types and tissues. An algorithm was then utilized to estimate a person's chronological age based on this data.
Turning back the clock on ageing
In California, Steve Horvath conducted a limited clinical trial which, for the first time in history, appeared to reverse indicators of ageing in people.
After twelve months, nine males between 51 and 65, who were all in good health, were given three drugs - one growth hormone and two drugs for diabetes. At the end of the year, it was observed that, on average, the individuals had reversed their biological age by 2.5 years, as measured by the Horvath epigenetic clock. Furthermore, there were indications that the participants' immune systems had become younger.
The researchers were astounded by the outcome, which was the opposite of what they had anticipated - a slowing down of the biological clock, not a reverse. Even though the research was a small sample size with no placebo control arm, it still showed promising results. However, there is still much work to be done before we are able to reverse ageing.
How might the discoveries concerning biological ageing affect the future?
To date, many ageing clocks have been created, yet they still pose a few issues. Primarily, they are 'noisy', meaning that the minute alterations of the methylation process that occur over time can be exaggerated by mistakes in methylation assessment. This ultimately renders the outcomes relatively imprecise.
Although these clocks are a decent way to measure someone's wellness, researchers are striving to make them more precise. Yet, as of now, they are not exact enough to be relied upon.
Epigenetic clocks are still in their early stages. Still, they have the potential to be used in the future to provide a more comprehensive understanding of an individual's health when coupled with other tests, such as measuring cholesterol and blood pressure.