On November 1, Nature published the latest findings of the joint research team of the Institute of Zoology of the Chinese Academy of Sciences and the Beijing Institute of Genomics, which took seven years to find a cell subtype toxic to motor neurons, and the team named it "AIMoN CPM". "Through the analysis of single cells, we found a group of unique cells in the spinal cord of elderly primates, which always surround the aging motor neurons." Liu Guanghui, the co correspondent author of the paper and a researcher at the Institute of Zoology of the Chinese Academy of Sciences, told the Science and Technology Daily that this unique gathering must have the purpose of life activities. After in-depth research, it was found that this group of cells secreted a "toxic" protein, It can accelerate the aging of motor neurons. The schematic diagram of aging spinal cord motor neurons being "surrounded" by AIMoN-CPM microglia reveals the source of motor neuron damage. As the saying goes, aging leads to aging of the legs. It can be seen that the first thing that degrades after aging is the ability to exercise. "Our research also confirmed that motor neurons are the most sensitive cell type to aging in the spinal cord." Sun Shuhui, the first author of the paper and assistant researcher of the Institute of Zoology of the Chinese Academy of Sciences, said that neurohistological analysis and research showed that with the significant increase of aging related markers in the motor neurons of primate spinal cord, the function of neurons showed a trend of degradation. Why do motor neuron cells, which only account for 0.3% to 0.4% of all spinal cord cells, bear the brunt of aging? What did they encounter? To unravel this mystery, the team created a high-resolution activity trajectory map at the single-cell level for the aging spinal cord of primates. "The trajectory map is complex, and the cell and molecular types are diverse, so we must draw it carefully to find the clues." Zhang Weiqi, co corresponding author of the paper and researcher of the Chinese Academy of Sciences Beijing Institute of Genomics, said that this part of research takes a long time. Through analysis of histopathology, cell biology, and molecular biology, researchers have discovered a new cell subtype (AIMoN-CPM) around aging motor neurons, which activates specific signals in peripheral motor neurons by secreting chitinase 1 protein, leading to their aging. It is reported that under normal circumstances, the concentration of chitinase 1 in the human body is very low, which can help the body fight against pathogens carrying chitin. But in specific disease states, it can be activated thousands of times, causing inflammation or damage. In the past, the research on the relevant mechanisms and mechanisms was not clear enough, but this study precisely identified a new subtype of neural cells as the source of chitinase 1, opening up a new direction for exploring the mechanism of aging. ▲ Tracer studies have shown that AIMoN-CPM microglia (red) in the spinal cord of aging primates aggregate at the axons of motor neurons (green). The latest human aging pathway is clear. "We found significant increases in chitinase 1 in the cerebrospinal fluid and serum of elderly people and monkeys," Zhang Weiqi said, which proves that the trajectory map discovered by our team at the molecular level does indeed exist in the human body. In order to further verify the toxicity of chitinase 1 secreted by a novel cell subset to motor neurons, researchers injected chitinase 1 with a surgical robot