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Human cerebral organoid (hCO) models offer the opportunity to understand fundamental processes underlying human-specific cortical development and pathophysiology in an experimentally tractable system. Although diverse methods to generate brain organoids have been developed, a major challenge has been the production of organoids with reproducible cell type heterogeneity and macroscopic morphology. Here, we have directly addressed this problem by establishing a robust production pipeline to generate morphologically consistent hCOs and achieve a success rate of >80%. These hCOs include both a radial glial stem cell compartment and electrophysiologically competent mature neurons. Moreover, we show using immunofluorescence microscopy and single-cell profiling that individual organoids display reproducible cell type compositions that are conserved upon extended culture. We expect that application of this method will provide new insights into brain development and disease processes.

IMPORTANCE Despite improvements in survival with aggressive chemoradiation, outcomes for patients diagnosed as having glioblastoma multiforme (GBM) remain poor. Survival is further limited in elderly patients, who are often unable to tolerate multimodality therapy. The appropriate treatment approach for elderly patients (aged >65 years) with GBM remains unclear. While the literature supports the use of standard radiotherapy (60 Gy), several recent studies have suggested that treatment with temozolomide monotherapy or short-course radiotherapy may be a reasonable alternative. OBJECTIVE To review literature reporting survival data related to treatment of elderly patients with GBM using either temozolomide alone or radiotherapy alone. EVIDENCE REVIEW We performed a systematic review to identify articles from the temozolomide era (2005-present) that reported survival data related to treatment of elderly patients with GBM using either temozolomide alone or radiotherapy alone, with consideration of O 6-methylguanine-DNA-methyltransferase gene (MGMT) promoter methylation status. PubMed was searched for articles between January 1, 2005, and August 31, 2013, using the search terms glioblastoma, elderly, temozolomide, radiation, hypofractionated, and survival, and references from relevant articles were searched. Selected articles reported overall survival data associated with either temozolomide alone or radiotherapy alone in elderly patients (aged Ն60 years) with GBM; articles were excluded if they did not report survival data from radiotherapy alone or temozolomide alone, were not restricted to an elderly population, did not report original data, were not restricted to patients with primary GBM, were a subgroup analysis of a prior article, were a case report, or could not be located in entirety. Articles were interrogated as per the criteria designated by the Oxford Centre for Evidence-Based Medicine to determine the level of evidence presented, and data from level 1 and 2 studies were used for analysis. From a review of 185 articles, 23 were selected for inclusion and final analysis. From these, we identified 2 level 1 studies and 1 level 2 study that reported overall survival in elderly patients treated with temozolomide alone, and 4 level 1 studies and 2 level 2 studies that reported overall survival in elderly patients treated with radiotherapy alone. FINDINGS This review of the literature revealed several limitations. First, there is a paucity of randomized clinical studies comparing temozolomide alone with radiotherapy alone in elderly patients with GBM. Second, there is a lack of coherence in the literature for the definition of elderly. Third, the treatment paradigms used are not consistent from study to study. Regardless, the available data did allow the formulation of a recommendation based on level 1 and 2 data. CONCLUSIONS AND RELEVANCE The literature supports the use of hypofractionated radiotherapy or temozolomide monotherapy in the treatment of elderly patients with GBM. In patients with MGMT promoter meth...

Mitochondrial health plays a crucial role in human brain development and diseases. However, the evaluation of mitochondrial health in the brain is not incorporated into clinical practice due to ethical and logistical concerns. As a result, the development of targeted mitochondrial therapeutics remains a significant challenge due to the lack of appropriate patient-derived brain tissues. To address these unmet needs, we developed cerebral organoids (COs) from induced pluripotent stem cells (iPSCs) derived from human peripheral blood mononuclear cells (PBMCs) and monitored mitochondrial health from the primary, reprogrammed and differentiated stages. Our results show preserved mitochondrial genetics, function and treatment responses across PBMCs to iPSCs to COs, and measurable neuronal activity in the COs. We expect our approach will serve as a model for more widespread evaluation of mitochondrial health relevant to a wide range of human diseases using readily accessible patient peripheral (PBMCs) and stem-cell derived brain tissue samples.

Establishing causal links between inherited polymorphisms and cancer risk is challenging. Here, we focus on the single-nucleotide polymorphism rs55705857, which confers a sixfold greater risk of isocitrate dehydrogenase ( IDH) –mutant low-grade glioma (LGG). We reveal that rs55705857 itself is the causal variant and is associated with molecular pathways that drive LGG. Mechanistically, we show that rs55705857 resides within a brain-specific enhancer, where the risk allele disrupts OCT2/4 binding, allowing increased interaction with the Myc promoter and increased Myc expression. Mutating the orthologous mouse rs55705857 locus accelerated tumor development in an Idh1 R132H -driven LGG mouse model from 472 to 172 days and increased penetrance from 30% to 75%. Our work reveals mechanisms of the heritable predisposition to lethal glioma in ~40% of LGG patients.

Mitochondrial health plays a crucial role in human brain development and diseases. However, the evaluation of mitochondrial health in the brain is not incorporated into clinical practice due to ethical and logistical concerns. As a result, the development of targeted mitochondrial therapeutics remains a significant challenge due to the lack of appropriate patient-derived brain 5 tissues. To address these unmet needs, we developed cerebral organoids (COs) from induced pluripotent stem cells (iPSCs) derived from human peripheral blood mononuclear cells (PBMCs) and monitored mitochondrial health from the primary, reprogrammed and differentiated stages. Our results show preserved mitochondrial genetics, function and treatment responses acrossPBMCs to iPSCs to COs, and measurable neuronal activity in the COs. We expect our approach 10

Human cerebral organoid (hCO) models offer the opportunity to understand fundamental processes underlying human specific cortical development and pathophysiology in an experimentally tractable system. While diverse methods to generate brain organoids have been developed, a major challenge has been the production of organoids with reproducible cell type heterogeneity and macroscopic morphology. Here, we directly addressed this problem by establishing a robust production pipeline to generate morphologically consistent (ie uniform) hCOs and achieve a success rate of >80%. These hCOs include both a radial glial stem cell compartment and electrophysiologically competent mature neurons. Moreover, we show using immunofluorescence microscopy and single cell profiling, that individual organoids display reproducible cell type compositions that are conserved upon extended culture. We expect that application of this method will provide new insights into brain development and disease processes.

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