Scientists develop “aging clocks” for individual cell types using a single blood test

Scientists have developed a method that can estimate how quickly different types of cells are aging from a single blood test and link these changes to the risk of serious diseases and death.

The study, published in Cell Reports Medicine, uses machine learning and an analysis of more than 7,000 plasma proteins. Using data from the Human Protein Atlas, researchers linked these proteins to more than 40 cell types and developed “aging clocks” for individual cell populations.

The models were tested in nearly 60,000 people using data from three large cohorts and two independent protein-analysis platforms, SomaScan and Olink.

The results showed that the biological age of different cell types can vary considerably within the same person. Some cell populations may age faster, while others can retain a more “youthful” state.

Cell aging may predict disease risk

The strongest associations were found between the aging of specific cell types and the risk of developing certain diseases later in life.

For example, extreme aging of astrocytes — cells in the nervous system that support the function of neurons — was the strongest predictor of Alzheimer's disease among the markers analyzed. Over a 15-year follow-up period, people with pronounced astrocyte aging had a 12.6-fold higher risk of developing Alzheimer's disease.

For comparison, carrying the APOE4 variant, which is associated with an increased risk of Alzheimer's, was linked to a 5.3-fold increase in risk. Polygenic risk was associated with a 2.14-fold increase, while chronological age increased the risk by 1.24 times.

The difference was particularly striking among people carrying two copies of APOE4. Alzheimer's disease developed in 38.3% of participants with extreme astrocyte aging, compared with 12.6% of those whose astrocytes showed normal aging.

The researchers also identified similar associations with other diseases.

Pronounced aging of skeletal muscle cells was associated with a 12.7-fold higher risk of amyotrophic lateral sclerosis (ALS). Accelerated aging of alveolar and respiratory epithelial cells was also linked to an increased risk of lung cancer, beyond the effect associated with smoking alone.

A broader measure of biological aging

The researchers also developed an overall measure called the Polycellular Aging Risk Score, which combines aging indicators from multiple cell types.

Among people showing pronounced aging in more than 20 cell populations, the 15-year survival rate was approximately 34%, compared with about 90% among people whose cellular aging measures were within the normal range.

The authors believe the approach could eventually become a tool for personalized medicine. Instead of assessing biological age only at the level of the entire body, a blood test could potentially reveal which specific cellular systems are aging faster and which diseases may be associated with those changes.

However, the findings are currently based on associations and do not mean that accelerated cellular aging directly causes the diseases identified. Further research will be needed to determine whether these cellular aging clocks can be used reliably for individual risk prediction or clinical decision-making.

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