A Humanized Mouse Model of Astrocytic Pathology in Schizophrenia

描述（由申请人提供）：人类进化伴随着星形细胞表型和功能的多样化，这有助于人类大脑功能和疾病的物种特异性方面。因此，人类星形细胞复杂性的发展与人类特有的精神疾病的进化过程是平行的，尤其是精神分裂症。然而，尽管星形胶质细胞病理可能与精神分裂症的思维紊乱有关，但星形胶质细胞病理在其发病机制中的作用一直难以研究，部分原因是缺乏人类神经胶质病理生理的动物模型。我们建议克服这一限制，使用我们开发的人类神经胶质嵌合小鼠大脑的新模型，结合我们新开发的从患者来源的人类诱导多能细胞（hiPSCs）高效可靠地生成星形胶质细胞的方案。我们将利用新生小鼠植入来自精神分裂症患者hipsc的神经胶质祖细胞（GPCs），评估精神分裂症患者来源的星形胶质细胞对疾病发病机制的具体贡献。在这些人类神经胶质嵌合小鼠大脑中，绝大多数常驻神经胶质细胞被人类gpc衍生的星形胶质细胞及其祖细胞所取代，从而可以在活的成年小鼠中评估人类神经胶质生理学、基因表达和对神经功能的影响。通过将这种嵌合方法与我们开发的从hiPSC中生成和纯化GPCs和星形胶质细胞的方案结合起来，并使用从青少年发作的精神分裂症患者身上产生的hiPSC系，我们将生产出主要来自精神分裂症患者的常驻胶质细胞的小鼠。在目的1中，我们将评估这些与精神分裂症相关的星形胶质细胞对嵌合小鼠皮质内胶质合胞传递的相对影响。在目标2中，我们接下来将评估嵌合小鼠的突触可塑性，以及精神分裂症来源的胶质嵌合对其行为表型和对药理学应激源的反应的影响。在Aim 3中，我们将对植入的星形胶质细胞进行分类，以便评估精神分裂症ipsc衍生的星形胶质细胞相对于正常hipsc衍生的胶质细胞的基因表达模式。通过这种多模式方法，我们希望确定相对于正常hipsc来源的胶质细胞，精神分裂症hipsc来源的星形胶质细胞的疾病特异性作用、基因表达模式和旁分泌毒性。这些不同的研究方向将为我们深入了解人类星形胶质细胞在精神分裂症发病机制中的物种和细胞类型特异性作用。同时，通过提供一个新的人类神经胶质嵌合模型系统，新的细胞试剂，以精神分裂症患者来源的星形胶质细胞的形式，以及新的基因表达数据库，涵盖精神分裂症hipsc来源的星形胶质细胞，该项目将使我们能够为该领域提供一套广泛而令人兴奋的新工具，能力和数据库。总之，这些应该大大加快我们对精神分裂症发病机制中人类神经胶质功能障碍的理解。

DESCRIPTION (provided by applicant): Human evolution has been accompanied by a diversification of astrocytic phenotype and function, that has contributed to species-specific aspects of both human brain function and disease. As such, the development of human astrocytic complexity has paralleled the appearance in evolution of psychiatric disorders unique to humans - the schizophrenias in particular. Yet despite this correlative suggestion that astrocytic pathology might contribute to the disordered thought of schizophrenia, the role of astroglial pathology in its pathogenesis has been difficult to study, in part because of the lack o animal models of human glial pathophysiology. We propose to overcome this limitation, using a new model of human glial-chimeric mouse brains that we have developed, paired with our newly-developed protocols for efficiently and reliably generating astrocytes from patient-derived human induced pluripotential cells (hiPSCs). Using mice neonatally engrafted with glial progenitor cells (GPCs) derived from hiPSCs generated from schizophrenic patients, we will assess the specific contributions of schizophrenic patient-derived astrocytes to disease pathogenesis. In these human glial chimeric mouse brains, the vast majority of resident glia are replaced by human GPC-derived astrocytes and their progenitors, allowing human glial physiology, gene expression, and effects on neural function to be assessed in live adult mice. By pairing this chimerization approach with protocols that we have developed for both generating and purifying GPCs and astrocytes from hiPSCs, and using hiPSC lines produced from patients with juvenile-onset schizophrenia, we will produce mice whose resident glia are largely derived from patients with schizophrenia. In Aim 1, we will assess the relative effects of these schizophrenia-associated astrocytes upon glial syncytial transmission within the cortices of the chimeric mice. In Aim 2, we will next assess the synaptic plasticity of the chimeric mice, as well as the effects of schizophrenia-derived glial chimerization upon their behavioral phenotype and responses to pharmacological stressors. In Aim 3, we will sort engrafted astroglia from the brains into which they have integrated, so as to assess the gene expression patterns of schizophrenic iPSC-derived astrocytes, relative to those of normal hiPSC-derived glia. By means of this multimodal approach, we hope to define the disease-specific effects, gene expression patterns, and paracrine toxicities of schizophrenic hiPSC-derived astrocytes relative to normal hiPSC-derived glia. These diverse lines of investigation should provide us great insight into the species- and cell type-specific roles of human astrocytes in the pathogenesis of schizophrenia. At the same time, by providing a new human glial chimeric model system, new cellular reagents in the form of schizophrenic patient-derived astrocytes, and new gene expression databases covering schizophrenic hiPSC-derived astrocytes, this project should allow us to make available to the field a broad and exciting new set of tools, capabilities and databases. Together, these should greatly accelerate our understanding of human glial dysfunction in the pathogenesis of schizophrenia.