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Astrocytes regulate glial scar formation in cerebral ischemic stroke
Yang Ting, Ding Zhibin, Jiang Nan, Han Hongxia, Hou Miaomiao, Ma Cungen, Song Lijuan, Li Xinyi
2024, 28 (1):
131-138.
doi: 10.12307/2023.742
BACKGROUND: Cerebral ischemic stroke is one of the main fatal and disabling diseases in the clinic, but only a few patients benefit from vascular recanalization in time, so it is urgent to explore new and effective therapy. As one of the critical pathological changes of ischemic stroke, the glial scar formed mainly by astrocytes is one major cause that hinders axonal regeneration and neurological recovery at the late stage of stroke.
OBJECTIVE: To elucidate the pathological process and crucial signal regulatory mechanism of astrocytes in the formation of glial scar after ischemic stroke, as well as the potential therapeutic targets, to provide a theoretical reference for intervening astrocytic scar formation against ischemic stroke effectively, and novel strategies for promoting post-stroke rehabilitation.
METHODS: The relevant articles published in CNKI, PubMed and Web of Science databases from 2010 to 2022 were retrieved. The search terms were “Ischemic stroke, Brain ischemi*, Cerebral ischemi*, Astrocyt*, Astroglia*, Glial scar, Gliosis, Astrogliosis” in Chinese and English. Finally, 78 articles were included after screening and summarized.
RESULTS AND CONCLUSION: (1) Astrocytes play an important role in the maintenance of central nervous system homeostasis. After ischemic stroke, astrocytes change from a resting state to an active state. According to the different severities of cerebral ischemic injury, astrocyte activation changes dynamically from swelling and proliferation to glial scar formation. (2) Mature astrocytes are stimulated to restart the cell cycle, then proliferate and migrate to lesions, which is the main source of the glial scar. Neural stem cells in the subventricular zone, neuron-glial antigen 2 precursor cells and ependymal precursor cells in the brain parenchyma can also differentiate into astrocytes. Endothelin-1, aquaporin 4, ciliary neurotrophic factor and connexins are involved in this process. In addition, chondroitin sulfate proteoglycan, as the main component of the extracellular matrix, forms the dense glial scar barrier with proliferated astrocytes, which hinders the polarization and extension of axons. (3) Activation or inhibition of crucial signal molecules involved in astrocyte activation, proliferation, migration and pro-inflammation functions regulate the glial scar formation. Transforming growth factor beta 1/Smad and Janus kinase/signal transducer and activator of transcription 3 are classical pathways related to astrogliosis, while receptor-interacting protein 1 kinase and glycogen synthase kinase 3β are significant molecules regulating the inflammatory response. However, there are relatively few studies on Smad ubiquitination regulatory factor 2 and Interleukin-17 and their downstream signaling pathways in glial scar formation, which are worthy of further exploration. (4) Drugs targeting astrogliosis-related signaling pathways, cell proliferation regulatory proteins and inflammatory factors effectively inhibit the formation of glial scar after cerebral ischemic stroke. Among them, the role of commonly used clinical drugs such as melatonin and valproic acid in regulating glial scar formation has been verified, which makes it possible to use drugs that inhibit glial scar formation to promote the recovery of neurological function in patients with stroke. (5) Considering the protective effects of glial scar in the acute phase, how to choose the appropriate intervention chance of drugs to maintain the protective effect of the glial scar while promoting nerve regeneration and repair in the local microenvironment is the direction of future efforts.
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