Effect of Passage Number on Human Induced Pluripotent Stem Cell Derived Neurons Culture Contaminants with Non-Neuronal Cell Types

Background: The study of live human neurons has been hindered due to the complexity and potential irreversible damage to the patient during biopsy. However, reprogramming of adult human somatic cells into induced pluripotent stem cells (iPSCs) has proved to be a novel method in the study of the pathophysiology of disease and therapeutic targets of the human nervous system. There are several approaches, and the optimum time (i.e., passage number) to generate highly pure cultures is being studied. Therefore, our laboratory has investigated the effect of passage number on culture contaminants with non-neuronal cell types. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood from three cell lines and reprogrammed into iPSCs. Each cell line consisted of three samples that were analyzed after low (5-10), middle (20-26), and high (30-38) number of passages. Cells were maintained in an induction medium for eight days. On day nine, cells were dissociated and replated in a maintenance medium. On day 33, total RNA was extracted from cells. Normalized values for non-neuronal cell marker genes were compared using paired Student’s t-tests and two-way ANOVA, with the cell line and passage number as independent variables. P-values less than 0.05 were considered significant. Results: Our results showed that lower passage number was associated with decreased astrocyte and chondrocyte marker expression. High passage number was associated with decreased oligodendrocyte and glial precursor marker expression. Of the fibroblast markers evaluated, there were similar trends of expression between all three groups. There was no significant difference in microglial cell marker gene expression between all three groups. Conclusion and Potential Impact: Low gene expression suggests a purer culture. According to these results, as passage number increases, there is more contaminants with oligodendrocytes and glial precursor cells. Conversely, with low passage numbers, there are more contaminants with astrocytes and chondrocytes. Future studies will identify the impact of these non-neuronal contaminants and implications on research.

HGG-06. EARLY GABAERGIC NEURONAL LINEAGE DEFINES DEPENDENCIES IN HISTONE H3 G34R/V GLIOMA

High-grade gliomas harboring H3 G34R/V mutations exclusively occur in the cerebral hemispheres of adolescents and young adults, suggesting a distinct neurodevelopmental origin. Combining multimodal bulk and single-cell genomics with unbiased genome-scale CRISPR/Cas9 approaches, we here describe a GABAergic interneuron progenitor lineage as the most likely context from which these H3 G34R/V mutations drive gliomagenesis, conferring unique and tumor-selective gene targets essential for glioma cell survival, as validated genetically and pharmacologically. Phenotypically, we demonstrate that while H3 G34R/V glioma cells harbor the neurotransmitter GABA, they are developmentally stalled, and do not induce the neuronal hyperexcitability described in other glioma subtypes. These findings offer a striking counter-example to the prevailing view of glioma origins in glial precursor cells, resulting in distinct cellular, microenvironmental, and therapeutic consequences.

Genetic Architectures and Cell-of-Origin in Glioblastoma

An aggressive primary brain cancer, glioblastoma (GBM) is the most common cancer of the central nervous system in adults. However, an inability to identify its cell-of-origin has been a fundamental issue hindering further understanding of the nature and pathogenesis of GBM, as well as the development of novel therapeutic targets. Researchers have hypothesized that GBM arises from an accumulation of somatic mutations in neural stem cells (NSCs) and glial precursor cells that confer selective growth advantages, resulting in uncontrolled proliferation. In this review, we outline genomic perspectives on IDH-wildtype and IDH-mutant GBMs pathogenesis and the cell-of-origin harboring GBM driver mutations proposed by various GBM animal models. Additionally, we discuss the distinct neurodevelopmental programs observed in either IDH-wildtype or IDH-mutant GBMs. Further research into the cellular origin and lineage hierarchy of GBM will help with understanding the evolution of GBMs and with developing effective targets for treating GBM cancer cells.

A giant solid cystic inferior fourth ventricle subependymoma – Case report and literature review

Subependymomas are a rare subtype of ependymomas, slow growing WHO grade I tumors that develop either intracranial from the subependymal glial precursor cells layer of the ventricles or intramedullary. These tumors originate in the undifferentiated Subependymal layer of cells that can become either ependymocytes or astrocytes. Most of the subependymomas are located inside the fourth ventricle (50-60%). We reviewed the case of a 40 years old woman with a giant solid cystic fourth ventricle ependymoma. The patient underwent total resection of the tumor through a subociipital transvermian approach. We discussed the characteristics of these benign tumors and reviewed the literature on this subject and concluded that total resection is the treatment of choice for symptomatic Subependymomas localized in posterior fossa.