Researchers at the Center for Molecular Medicine of the Austrian Academy of Sciences and the Ludwig Boltzmann Institute for Medical Science at the University of Vienna have developed an artificial intelligence system they call a "tissue clock" to measure the biological age of human organs. The system estimates organ age based on histological images of tissue samples. Experts say that chronological age listed on a birth certificate represents only a partial understanding of aging.
The research team analyzed more than 25,000 images of tissue samples from 40 different organ types, including the brain, heart, lungs, pancreas, skin and intestines. The team converted these samples from a database of 983 people into high-quality digital images revealing the microscopic structure of each organ. Using advanced computational imaging models, the researchers analyzed approximately 480 million individual image segments.
The study found that human organs do not age at the same rate, with different tissues following distinct aging trajectories. Some organs—including the lungs, kidneys, pancreas and adrenal gland—showed accelerated aging beginning in early adulthood, between ages 20 and 40, while aging in other organs accelerated at later life stages. The research team was led by study author André Rendeiro and used one of the world's largest collections of human tissue samples.
The findings showed that accelerated aging in some organs may be linked to specific diseases or physiological changes, such as kidney failure in the kidneys, menopause in the uterus, and diabetes in the pancreas. The researchers also attempted to measure organ age using blood samples by comparing gene expression in blood samples with ages determined from tissue images of the same people.
Blood-based markers were able to identify tissue ages in patients with diseases including Alzheimer's, cystic fibrosis, vasculitis and diabetes. The research team said the strongest indicators of aging appeared in brain tissue samples.