The different organs and tissues of the human body age at different speeds and the one that ages the fastest is the one that has the most influence on the health and longevity of the person, according to research from Stanford University (USA) that lays the foundations for understanding better aging and develop therapies to counteract it. The authors of the research have developed a test based on a blood analysis that indicates the biological age of the different organs and tissues of the human body.
The research questions the idea that the entire organism has the same biological age, which may or may not coincide with the chronological age. The results indicate that each organ and tissue has its own biological age, which can be estimated from the proteins they release into the blood.
"A molecular understanding of the aging of human organs (...) could revolutionize patient care, preventive medicine and drug development", write the researchers in the journal Nature, in which they presented the data yesterday.
The work was based on blood samples from 5,676 people in the US who participated in studies on aging and cognitive decline since 2008. Using proteomics techniques, the levels of 4,979 proteins in the blood samples were analyzed . By combining them with deep learning techniques, which is a branch of artificial intelligence, it has been identified which proteins report on the age of specific organs.
In one of the examples that was known before this research and that has been confirmed, the levels of transaminases report on the state of the liver. Other examples were previously unknown and have now been discovered by combining proteomic analysis with artificial intelligence.
The results indicate that one in five apparently healthy people over the age of 50 have an organ that is aging faster than the rest of the body. The researchers expected that accelerated aging would be synchronized between different organs in the body, but the data indicate otherwise: only one in 60 people has two or more organs that age in an accelerated way. The Stanford team concludes that the rate of aging not only varies between people, but also between the different organs in each person.
Another expectation of the researchers has indeed been fulfilled: the accelerated aging of an organ increases the risk of serious illness and premature death. For example, every additional year in the biological age of the heart increases the risk of heart failure by 23%. Aging of the kidneys increases the risk of developing diabetes or hypertension. And that of the muscles, a faster deterioration of the gait and a greater risk of falls.
"We can calculate the biological age of an organ in an apparently healthy person," said neurologist Tony Wyss-Coray, director of the research, in a statement. "This, in turn, predicts the risk of disease related to this organ."
Of the eleven organs and tissues that have been analyzed, none of them has a tendency to age faster than the others. In addition to the heart, kidneys and muscles, the brain, lungs, liver, pancreas, intestine, immune system, vascular system and fat tissue have been analysed.
Looking to the future, the researchers hope that some of the proteins associated with aging that they have identified can guide the development of new drugs. They give the example of the protein MYL7, known but still little studied, as "a promising target for hypertrophic cardiomyopathy", as they write in Nature.
Another perspective is to expand the database with more organs and more proteins to achieve a more precise understanding of aging. "As more proteomics resources emerge, the potential of this strategy will increase (...) We anticipate that more biological information can be obtained with more proteomic coverage", they write in Nature.
For now, the test to find out the biological age of the organs with a blood test is experimental. The director and two co-authors of the research have created the company Teal Omics so that the results of the project are commercialized, available to other doctors and scientists and reach citizens.
