Cellular aging plays an important role in physiological and pathological processes such as embryonic development, injury regeneration, cancer, and body aging. Both are 'elderly' cells, but there are good and bad, some causing chaos in the body, while others silently protect health. How to accurately identify and distinguish between "good" and "bad" individuals in the aging cell population has been a long-standing challenge in the field of cellular aging. Recently, Zhou Bin, the research team of the Center for Excellence and Innovation in Molecular Cell Science of the Chinese Academy of Sciences, systematically discussed the fate track and specific role of aging cells of different cell types in the process of liver injury and repair through technological innovation, and realized more accurate "punishing evil and promoting good" on the model of liver injury mice. The relevant results were recently published in the international academic journal Cell. Researchers first developed a lineage tracing system for aging cells in vivo, and then established functional research techniques for aging cells of different cell types. Based on this, researchers found in a mouse model that cellular aging after liver injury mainly involves macrophages and endothelial cells. Aging macrophages surge during liver injury and promote liver fibrosis by secreting inflammatory factors after injury; Aging endothelial cells, although showing signs of aging after liver damage, still play an important role in the repair process, limiting damage and fibrosis. Clearing aging macrophages can limit liver fibrosis. On the contrary, after the aging endothelial cells are cleared, the liver tissue transitions to a pro fibrotic environment. Researchers have also achieved reprogramming of aging endothelial cells in the body and found that this group of aging cells can significantly reduce the degree of liver fibrosis after "rejuvenation". This work provides important research techniques for the field of cellular aging and regenerative medicine, as well as new research directions and theoretical basis for the clinical treatment of liver related diseases. (New Society)