[Isolation, culture and inflammatory characteristics of astrocytes in aged rats nervous tissue].

Objective: To establish an optimized method for the isolation and purification of astrocytes from the neural tissues of young and aged rats. Then, the morphological and functional differences of astrocytes between young and aged rats were compared to explore the functional changes of astrocytes after aging and its possible mechanism in the aging process. Methods: Young (2 months old) and aged (20 months old) SD rats were used. Astrocytes in brain and spinal cord tissue were purified by 50% - 35% percoll density gradient centrifugation. Each group of cells was set up with three duplicate wells. After 72 h of culture, Glial fibrillary acidic protein (GFAP) which was astrocyte specific marker were detected by immunofluorescence to evaluate the morphological characteristics. Cell senescence markers (p16 and p21) and β- Galactosidase were detected by qPCR and staining respectively. The expressions of pro-inflammatory cytokines (IL-1β, TNF-α) and anti-inflammatory cytokines were detected by qPCR. Results: Using 50%-35% percoll gradient separation, astrocytes were obtained with large number, good activity and purity of more than 95%, which could be used in subsequent experiments. Compared with the astrocytes in the nerve tissue of young rats, the astrocytes in the nervous tissue of the aged rats had fewer protrusions and tended to be activated in cell morphology; the positive rate of β -galactosidase staining was increased significantly and the expressions of p16 and p21 were increased (P<0.01). The expressions of pro-inflammatory cytokines (IL-1β, TNF-α) were increased (P<0.05), and the expression of anti-inflammatory cytokine (IL-10) was decreased (P<0.05) in astrocytes of the aged rats nervous tissue. Conclusion: The percoll gradient of 50% - 35% could be used as a method for separation, purification and primary culture of astrocytes. With the increase of age, astrocytes undergo cellular senescence, showing a pro-inflammatory phenotype, promoting inflammaging of the nervous system, which may be one of the mechanisms of nervous system aging and neurodegenerative diseases.