A Humanized Mouse Model of Astrocytic Pathology in Schizophrenia

描述(申请人提供)：人类进化伴随着星形胶质细胞表型和功能的多样化，这对人类大脑功能和疾病的物种特异性方面都有贡献。因此，人类星形细胞复杂性的发展与人类特有的精神疾病--特别是精神分裂症--在进化过程中的出现是平行的。然而，尽管星形胶质细胞病理学可能有助于精神分裂症的无序思维，但星形胶质细胞病理学在其发病机制中的作用一直很难研究，部分原因是缺乏人类神经胶质病理生理学的动物模型。我们建议克服这一限制，使用我们开发的一种新的人类神经胶质嵌合小鼠脑模型，与我们新开发的协议相结合，从患者来源的人类诱导多潜能细胞(HiPSCs)高效而可靠地生成星形胶质细胞。利用从精神分裂症患者产生的神经胶质前体细胞(GPC)移植到新生小鼠身上，我们将评估精神分裂症患者来源的星形胶质细胞在疾病发病机制中的特殊贡献。在这些人胶质嵌合的小鼠大脑中，绝大多数常驻的胶质细胞被人类GPC来源的星形胶质细胞及其祖细胞取代，这使得可以在活的成年小鼠身上评估人类神经胶质的生理学、基因表达和对神经功能的影响。通过将这种嵌合化方法与我们开发的从HiPSCs中生成和纯化GPC和星形胶质细胞的方案相结合，并使用从青少年精神分裂症患者产生的HiPSC系，我们将产生其常驻胶质细胞主要来自精神分裂症患者的小鼠。在目标1中，我们将评估这些精神分裂症相关星形胶质细胞对嵌合小鼠皮质内神经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，以及精神分裂症衍生的神经胶质嵌合化对它们的行为表型和对药物应激源的反应的影响。在目标3中，我们将对植入的星形胶质细胞进行分类，以评估精神分裂症患者IPSC来源的星形胶质细胞相对于正常hPSC来源的星形胶质细胞的基因表达模式。通过这种多模式方法，我们希望确定精神分裂症HIPSC来源的星形胶质细胞相对于正常HIPSC来源的胶质细胞的疾病特异性效应、基因表达模式和旁分泌毒性。这些不同的研究路线应该为我们提供对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的更大洞察力。同时，通过提供新的人类神经胶质嵌合模型系统、精神分裂症患者来源的星形胶质细胞形式的新细胞试剂以及涵盖精神分裂症HiPSC来源的星形胶质细胞的新基因表达数据库，该项目应该允许我们向该领域提供一套广泛和令人兴奋的新工具、功能和数据库。综上所述，这些应该会极大地促进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.