The Biological Clock for Some Tissues May Be Ticking Faster than for Others

       Popular Science recently posted an article about Steve Hovarth, a geneticist at UCLA’s medical school, who has developed a new technique for identifying the exact biological age of human tissue. His research suggests that not all tissues of the body follow the same biological clock. The process involves the observation of DNA methylation, which has been suggested to be a biomarker for the age of a cell. As hypothesized, cancerous tissues age far faster than healthy tissue. However, it was also displayed that even some healthy tissues age faster than the rest of the body; in Hovarth’s study, breast tissue was examined. While completely healthy breast tissue is two to three years older than the rest of the female body, it was also shown that tumors aged the tissue an additional 36 years, and healthy breast tissue that was near a tumor was about 12 years older than tissue in other parts of the body.

Hovarth’s study highlighted over 8,000 healthy samples of 51 different types of tissues. He then went even further to study 6,000 samples of cancerous tissue. For each sample, Hovarth examined the DNA methylation levels of the given tissue. Once the biological age of the tissue was determined through the observation of DNA methylation levels, Hovarth compared the biological age of the tissue to the chronological age of the issue donor. His method was virtually completely successful. Not only did Hovarth’s study find a method of effectively calculating the age of various tissues, but he was also able to transform adult human cells into pluripotent stem cells. This transformation essentially rearranges the cells so that they act as if they were embryonic stem cells; Hovarth commented that this transformation “resets the cells’ clock to zero.”

I found this article particularly interesting not only because it explains how some tissues are biologically older than the rest of the body, but also because it proposes a way to essentially reverse that aging process. Looking at this article from a health perspective, it is fascinating how some parts of the body can age faster than others; this increased age of certain tissues definitely makes them more susceptible to acquire different diseases and illnesses. If Hovarth’s method of reprogramming cells to make them act as embryonic stem cells proves to be effective, then not only can the medical community use this method to combat different diseases, but it can also be utilized as a new weapon in the ongoing war against aging. I am a gerontology minor, so I have been learning a lot about the downside of aging as well as the biological aspects of aging. It is exciting to think that in the near future, this method can be perfected and used to improve the health of the population of individuals who are experiencing difficulty or discomfort when aging.

Aging Changes all Tissues

Reading Your Biological Clock

UCLA professor Steve Horvath used eight thousand samples of fifty-one tissue and cell types in order to develop a new way to understand the biological clock. Specifically, he used over 350 genetic markers to track the relationship age and methylation levels. From his results, he noticed that different types of tissue aged differently when compared to different tissue found on the same body. Specifically, he noticed that healthy breast tissue was two to three years older than the rest of a woman's body when compare to abnormal cancerous breast tissue that, was on average, twelve years older than the rest of another woman's body. He also observed that biological clock is not moving at a constant rate. The clock ticks faster during the earlier stages of life up until the age of twenty. From there, the biological clock was shown to slow down until a constant rate was reached.

I understand that everyone's clock is not same, but this new biological clock can be used as a guide to help us indicate potential issues within our tissue. With more studies, patterns could be developed to indicated a deleterious change compared to a normal change. With further research, people can start to understand some of the processes related to primary aging and the changes that are associated with it on a molecular level. By knowing the relative age of different tissues within the body, specific preventative medicines could be designed to slow down aging in order to prevent possible disease. Aging is a very complex process. Understanding its fundamental processes can help correct age-related diseases or lower risks for diseases.