As people age, they are more susceptible to chronic diseases such as cancer, heart disease, and dementia. Instead of fighting these diseases one by one, scientists are increasingly concerned about a more fundamental question, which is whether aging itself can be slowed down. A new study from Rockefeller University in the United States provides important clues for understanding this issue. Researchers have created the most comprehensive mammalian aging cell map to date, systematically revealing the patterns of cell changes with age in different organs. The relevant results were published in the latest issue of the journal Science. This atlas system demonstrates how aging affects thousands of cell subtypes in 21 tissues within mammals. To complete this research, the team optimized a technique called single-cell ATAC seq, which can determine whether genes are active by analyzing the degree of DNA openness in cells. They analyzed nearly 7 million cells from 32 mice and 21 organs. The ages of the mice are 1 month (young adult), 5 months (middle-aged), and 21 months (elderly). As a result, over 1800 cell subtypes were ultimately identified, including many rare cell types that had not been previously described. They found that some age-related changes begin to appear in earlier stages of life. For example, when mice are 5 months old, the number of some cell populations has shown a downward trend. About 1/4 of cell types show significant increases or decreases with age. For example, the number of some muscle and kidney cells significantly decreases, while multiple immune cells expand with age. In addition, changes between different organs exhibit significant synchronicity, with similar cellular states appearing or decreasing simultaneously in multiple tissues. This phenomenon suggests that there may be signaling molecules transmitted through blood circulation in the body that coordinate the aging process throughout the body. The study also found significant gender differences, with about 40% of age-related changes varying between males and females. For example, females exhibit broader immune system activation during the aging process, which may be related to their increased susceptibility to certain autoimmune diseases. At the molecular level, the research team analyzed approximately 1.3 million genomic regulatory regions, of which around 300000 regions underwent significant changes during the aging process. About 1000 changes occur simultaneously in multiple cell types, many of which are related to immune response, inflammation, and stem cell maintenance. The research team believes that these "regulatory hotspots" may be important breakthroughs in understanding aging mechanisms and developing intervention methods. After further comparing existing studies, the team found that immune signaling molecules, namely cytokines, can induce cellular changes similar to aging. The research team speculates that in the future, if these signaling pathways can be regulated through drugs, it may be possible to slow down aging related processes at multiple organ levels. (New Society)