Regional characterization of astrocytes in the human brain

直到20世纪90年代，星形胶质细胞在很大程度上被认为是中枢神经系统的被动成分，主要为神经元提供结构支持。现在很清楚，星形胶质细胞是高度动态的细胞，对大脑网络的正常功能起着各种重要作用。然而，我们目前对这些细胞形态功能特性的了解主要来自动物模型，特别是啮齿动物模型的研究。尽管啮齿类动物和人类大脑的基本组织有许多相似之处，但在细胞水平上存在显著差异。我们和其他研究小组的工作最近表明，人类皮层星形胶质细胞比啮齿动物的同类细胞要复杂和多样得多。尽管最近有了这些发现，但关于人脑星形胶质细胞的细胞和亚细胞组织以及分子特性，仍有许多有待发现。特别是，对于其他非皮质脑区星形胶质细胞的形态计量学和分子特征几乎一无所知。******主要和具体目标：本研究计划的主要目标是表征人类大脑不同区域星形细胞亚型的分布、形态计量学和转录组学特征。更具体地说，我们将使用精细的神经解剖学和分子方法来定性和定量地描述星形胶质细胞在大脑皮层和皮层下不同区域的分布和细胞/亚细胞特性，并以细胞群体特异性的方式表征区域星形胶质细胞基因表达谱。******方法：从加拿大道格拉斯-贝尔脑库获得特征明确的固定和冷冻死后脑样本。这些样本将来自健康的35-40岁的男性和女性捐赠者，没有精神、神经或慢性炎症病史。在我的实验室中经常使用的最先进的方法将用于量化区域星形细胞密度和形态特征。这些包括免疫染色细胞的立体定量和三维细胞重建。在每个区域，星形胶质细胞将通过激光捕获显微解剖提取，并通过超低输入RNA测序确定其转录组谱。******意义：本研究有望发现新的星形细胞亚型，星形细胞网络的不同区域特性将会显现。这将使我们更好地了解人类大脑的精细结构和功能组织。

Introduction: Until the 1990s, astrocytes were largely considered to be passive components of the central nervous system, providing mainly structural support for neurons. It is now clear that astrocytes are highly dynamic cells that play a variety of roles that are essential for the proper function of cerebral networks. However, our current knowledge on the morpho-functional properties of these cells comes essentially from studies conducted with animal models, rodents in particular. Despite the many similarities in the basic organization of rodent and human brains, significant differences can exist at the cellular level. Our work as well as that of other groups has recently shown that human cortical astrocytes are much more complex and diverse than their rodent counterparts. Despite these recent findings, much remains to be discovered regarding the cellular and subcellular organization and molecular properties of astrocytes in the human brain. In particular, virtually nothing is known about the morphometric and molecular features of astrocytes in other, non-cortical, brain regions.******Main and specific objectives: The main objective of this research program is to characterize the distributional, morphometric and transcriptomic profiles of astrocytic subtypes found in different regions of the human brain. More specifically, we will use fine neuroanatomical and molecular approaches to describe, qualitatively and quantitatively, the distribution and cellular/subcellular properties of astrocytes in various cortical and subcortical brain regions, and characterize in a cell population-specific manner the regional astrocytic gene expression profiles.******Methods: Well-characterized fixed and frozen postmortem brain samples will be obtained from the Douglas-Bell Canada Brain Bank. These samples will come from healthy 35-40 year-old male and female donors with no history of psychiatric, neurological, or chronic inflammatory conditions. State-of-the-art approaches routinely used in my laboratory will be employed to quantify regional astrocytic densities and morphological features. These include stereological quantifications of immunostained cells and 3D cell reconstructions. In each region, astrocytes will be extracted by laser-capture microdissection, and their transcriptomic profiles determined following ultra-low input RNA sequencing.******Significance: It is expected that this research will lead to the identification of new astrocytic subtypes, and that distinct regional properties of astrocytic networks will emerge. This will allow us to better understand the fine structural and functional organization of the human brain.