The Role of Microglial Depletion Approaches in Pathological Condition of CNS.

Microglia are the primary immune cells of the central nervous system (CNS) that comprise about 5-12% of all cells in the brain. These cells are the first line of defense that protects the CNS from damage and attacking pathogens. Microglia originate from yolk sac macrophages and migrate to the brain before the blood-brain barrier formation. Microglia show key roles in healthy CNS including promoting neurogenesis, synaptic sculpting, and maintaining homeostasis but in pathological conditions of CNS, microglial activation may exacerbate diseases. Thus, microglial depletion of the CNS is a novel approach that could be a useful tool to understand the microglial functions in neurodegenerative and neuroinflammatory diseases. There are methods for microglial ablation and reduction such as genetic tools and pharmacological inhibitors. In this study, we review recent studies that used different microglial ablation models for microglial reduction and repopulation after depletion in pathological states of CNS. Recently, studies showed that microglial depletion as a potential therapeutic application has benefits (such as inflammatory factors reduction, increase synaptogenesis, astrogliosis preventation) in CNS. For these reasons, the inhibition of microglia with these models was considered a therapeutic approach for neurodegenerative disease treatment.