Microglia are brain resident macrophages originated from primitive progenitor cells in the yolk sac. Microglia can be activated within hours and recruited to the lesion site. Traditionally, microglia activation is considered to play a deleterious role in ischemic stroke, as inhibition of microglia activation attenuates ischemia induced brain injury. However, increasing evidence show that microglia activation is critical for attenuating neuronal apoptosis, enhancing neurogenesis, and promoting functional recovery after cerebral ischemia. Differential polarization of microglia could likely explain the biphasic role of microglia in ischemia. We comprehensively reviewed the mechanisms involved in regulating microglia activation and polarization. The latest discoveries of microRNAs in modulating microglia function are discussed. In addition, the interaction between microglia and other cells including neurons, astrocytes, oligodendrocytes, and stem cells were also reviewed. Future therapies targeting microglia may not exclusively aim at suppressing microglia activation, but also at modulating microglia polarization at different stages of ischemic stroke. More work is needed to elucidate the cellular and molecular mechanisms of microglia polarization under ischemic environment. The roles of microRNAs and transplanted stem cells in mediating microglia activation and polarization during brain ischemia also need to be further studied.

小胶质细胞是源自卵黄囊原始祖细胞的常驻巨噬细胞。小胶质细胞可以在数小时内激活并募集到病变部位。传统上，小胶质细胞活化被认为在缺血性中风中起有害作用，因为抑制小胶质细胞活化可减轻局部缺血引起的脑损伤。然而，越来越多的证据表明，小胶质细胞活化对于减轻脑缺血后神经元凋亡，增强神经发生和促进功能恢复至关重要。小胶质细胞的极化分化可能可以解释小胶质细胞在缺血中的两相作用。我们全面审查了涉及调节小胶质细胞活化和极化的机制。讨论了microRNA在调节小胶质细胞功能中的最新发现。此外，还综述了小胶质细胞与其他细胞（包括神经元，星形胶质细胞，少突胶质细胞和干细胞）之间的相互作用。靶向小胶质细胞的未来疗法可能不仅旨在抑制小胶质细胞的活化，而且还旨在调节缺血性卒中不同阶段的小胶质细胞极化。需要更多的工作来阐明在缺血环境下小胶质细胞极化的细胞和分子机制。microRNA和移植的干细胞在介导脑缺血期间介导小胶质细胞活化和极化中的作用也需要进一步研究。而且还可以调节缺血性卒中不同阶段的小胶质细胞极化。需要更多的工作来阐明在缺血环境下小胶质细胞极化的细胞和分子机制。microRNA和移植的干细胞在介导脑缺血期间介导小胶质细胞活化和极化中的作用也需要进一步研究。而且还可以调节缺血性卒中不同阶段的小胶质细胞极化。需要更多的工作来阐明在缺血环境下小胶质细胞极化的细胞和分子机制。microRNA和移植的干细胞在介导脑缺血期间介导小胶质细胞活化和极化中的作用也需要进一步研究。