Glioblastomas (GBMs) functionally integrate into diverse neuronal circuits within the central nervous system, which can promote tumor progression and affect neurons via neuron-to-glioma synapses. It remains challenging to identify and manipulate tumor-innervating neurons, which may remain localized or widely distributed throughout the brain. Building on GBM organoids (GBOs) derived from patient-resected surgical tissue, we present here detailed procedures for assessing interactions between tumors and neurons. We first discuss retrograde trans-monosynaptic tracing approaches to study the neuron-tumor connectome by using a rabies viral system in ex vivo human tissue and in xenogenic animal models. As a complementary approach, we then describe the use of anterograde transsynaptic tracing using herpes simplex virus in vivo and ex vivo to assess brain region-specific connectivity in GBMs. In addition, to facilitate the adaptability of these tracing methodologies in diverse systems, we provide procedures for the viral transduction into GBOs, the generation of assembloids comprising GBOs and human induced pluripotent stem cell-derived cortical organoids and the establishment of air-liquid interface cultures from surgical human brain tissue. Together, these techniques permit the flexible characterization and manipulation of tumor-neural circuits and can be easily adapted to other cancers with nervous system involvement. After the generation of GBOs and/or cortical organoids, transsynaptic tracing requires 12-35 d to complete ex vivo or in vivo. The procedure is suitable for users with expertise in human cell and organoid culture, viral production and transduction, rodent surgery and microscopy.

Chromatin is organized into multiscale three-dimensional structures, including chromosome territories, A/B compartments, topologically associating domains, and chromatin loops. This hierarchically organized genomic architecture regulates gene transcription, which, in turn, is essential for various biological pro-cesses during brain development and adult plasticity. Here, we review different aspects of spatial genome organization and their functions in regulating gene expression in the nervous system, as well as their dysre-gulation in brain disorders. We also highlight new technologies to probe and manipulate chromatin architec-ture and discuss how investigating spatial genome organization can lead to a better understanding of the nervous system and associated disorders.

Brain organoids are self-organized three-dimensional aggregates generated from pluripotent stem cells. They exhibit complex cell diversities and organized architectures that resemble human brain development ranging from neural tube formation, neuroepithelium differentiation, neurogenesis and gliogenesis, to neu-ral circuit formation. Rapid advancements in brain organoid culture technologies have allowed research -ers to generate more accurate models of human brain development and neurological diseases. These models also allow for direct investigation of pathological processes associated with infectious diseases affecting the nervous system. In this review, we first briefly summarize recent advancements in brain orga-noid methodologies and neurodevelopmental processes that can be effectively modeled by brain orga-noids. We then focus on applications of brain organoids to investigate the pathogenesis of neurotropic viral infection. Finally, we discuss limitations of the current brain organoid methodologies as well as appli-cations of other organ specific organoids in the infectious disease research.(c) 2021 Elsevier Ltd. All rights reserved.

As antiretroviral therapy (ART) becomes increasingly affordable and accessible to women of childbearing age across the globe, the number of children who are exposed to Human Immunodeficiency Viruses (HIV) but remain uninfected is on the rise, almost all of whom were also exposed to ART perinatally. Although ART has successfully aided in the decline of mother-to-child-transmission of HIV, the long-term effects of in utero exposure to ART on fetal and postnatal neurodevelopment remain unclear. Evaluating the safety and efficacy of therapeutic drugs for pregnant women is a challenge due to the historic limitations on their inclusion in clinical trials and the dynamic physiological states during pregnancy that can alter the pharmacokinetics of drug metabolism and fetal drug exposure. Thus, much of our data on the potential consequences of ART drugs on the developing nervous system comes from preclinical animal models and clinical observational studies. In this review, we will discuss the current state of knowledge and existing approaches to investigate whether ART affects fetal brain development, and describe novel human stem cell-based strategies that may provide additional information to better predict the impact of specific drugs on the human central nervous system.Approaches to evaluate the impact of drugs on the developing brain. Dysregulation of the developing nervous system can lead to long-lasting changes. Integration of data from animal models, clinical observations, and cell culture studies is needed to predict the safety of therapeutic antiretroviral drugs during pregnancy. New approaches include human induced pluripotent stem cell (iPSC)-based 2D and 3D models of neuronal networks and brain regions, as well as single cell profiling in response to drug exposure.

As antiretroviral therapy (ART) becomes increasingly affordable and accessible to women of childbearing age across the globe, the number of children who are exposed to Human Immunodeficiency Viruses (HIV) but remain uninfected is on the rise, almost all of whom were also exposed to ART perinatally. Although ART has successfully aided in the decline of mother-to-child-transmission of HIV, the long-term effects of in utero exposure to ART on fetal and postnatal neurodevelopment remain unclear. Evaluating the safety and efficacy of therapeutic drugs for pregnant women is a challenge due to the historic limitations on their inclusion in clinical trials and the dynamic physiological states during pregnancy that can alter the pharmacokinetics of drug metabolism and fetal drug exposure. Thus, much of our data on the potential consequences of ART drugs on the developing nervous system comes from preclinical animal models and clinical observational studies. In this review, we will discuss the current state of knowledge and existing approaches to investigate whether ART affects fetal brain development, and describe novel human stem cell-based strategies that may provide additional information to better predict the impact of specific drugs on the human central nervous system.Approaches to evaluate the impact of drugs on the developing brain. Dysregulation of the developing nervous system can lead to long-lasting changes. Integration of data from animal models, clinical observations, and cell culture studies is needed to predict the safety of therapeutic antiretroviral drugs during pregnancy. New approaches include human induced pluripotent stem cell (iPSC)-based 2D and 3D models of neuronal networks and brain regions, as well as single cell profiling in response to drug exposure.