Alternatives Unit, Biomedical Primate Research Centre, Rijswijk, The Netherlands.
Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
Glia. 2022 Apr;70(4):728-747. doi: 10.1002/glia.24136. Epub 2021 Dec 28.
Microglia are increasingly being recognized as druggable targets in neurodegenerative disorders, and good in vitro models are crucial to address cell biological questions. Major challenges are to recapitulate the complex microglial morphology and their in vivo transcriptome. We have therefore exposed primary microglia from adult rhesus macaques to a variety of different culture conditions including exposure to soluble factors as M-CSF, IL-34, and TGF-β as well as serum replacement approaches, and compared their morphologies and transcriptomes to those of mature, homeostatic in vivo microglia. This enabled us to develop a new, partially serum-free, monoculture protocol, that yields high numbers of ramified cells. We also demonstrate that exposure of adult microglia to M-CSF or IL-34 induces similar transcriptomes, and that exposure to TGF-β has much less pronounced effects than it does on rodent microglia. However, regardless of culture conditions, the transcriptomes of in vitro and in vivo microglia remained substantially different. Analysis of differentially expressed genes inspired us to perform 3D-spherical coculture experiments of microglia with oligodendrocytes and radial glia. In such spheres, microglia signature genes were strongly induced, even in the absence of neurons and astrocytes. These data reveal a novel role for oligodendrocyte and radial glia-derived cues in the maintenance of microglial identity, providing new anchor points to study microglia in health and disease.
小胶质细胞越来越被认为是神经退行性疾病的可药物靶点，良好的体外模型对于解决细胞生物学问题至关重要。主要的挑战是再现复杂的小胶质细胞形态及其体内转录组。因此，我们将成年恒河猴的原代小胶质细胞暴露于多种不同的培养条件下，包括暴露于 M-CSF、IL-34 和 TGF-β 等可溶性因子以及血清替代方法，并将其形态和转录组与成熟、体内稳态的小胶质细胞进行比较。这使我们能够开发一种新的、部分无血清的单核培养方案，该方案可产生大量的树突状细胞。我们还证明，成年小胶质细胞暴露于 M-CSF 或 IL-34 会诱导相似的转录组，而暴露于 TGF-β 的效果远不及对啮齿动物小胶质细胞的影响。然而，无论培养条件如何，体外和体内小胶质细胞的转录组仍然存在很大差异。差异表达基因的分析促使我们进行了小胶质细胞与少突胶质细胞和放射状胶质细胞的 3D 球形共培养实验。在这些球体中，即使没有神经元和星形胶质细胞，小胶质细胞特征基因也被强烈诱导。这些数据揭示了少突胶质细胞和放射状胶质细胞衍生信号在维持小胶质细胞特性中的新作用，为研究健康和疾病中小胶质细胞提供了新的研究切入点。
