Date of Award

2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Biochemistry & Molecular Biophysics

First Advisor

Hongjun Song

Abstract

Neurological diseases, including brain cancers, involve complex interactions between different cell types in typified cytoarchitectures and microenvironmental niches; however, many laboratory models inadequately capture this heterogeneity and thus limit the investigation of important underlying biological processes. Building on our work with brain organoid models of early neural development, we established patient-derived glioblastoma (GBM) organoids (GBOs) as models of inter- and intra-tumoral heterogeneity. We performed extensive histological, genetic, and transcriptomic analyses to demonstrate that these GBOs maintain the diverse cellular composition, somatic mutational landscape, and transcriptomic states of their corresponding parental tumors. Importantly, non-neoplastic tumor resident cells, such as macrophages, microglia, vascular cells, and oligodendrocytes are preserved in GBOs, allowing for investigation of the tumor microenvironment with this cellular context intact. GBOs are amenable to a wide range of experimental manipulations, such as orthotopic xenograft for studies of tumor cell infiltration and drug screening for personalized medicine or chemical genetics. These studies validate the fidelity of GBOs to their parental tumors and highlight the unique advantages and opportunities available with this laboratory model of GBM

Chimeric antigen receptor modified (CAR) T cell therapy has achieved remarkable outcomes in certain treatment resistant malignancies, however, trials in GBM have yet to yield broad success. Correlative studies have pointed towards an adaptive tumor response in opposition to the cellular immunotherapy as important in mediating overall treatment inefficacy, though the specific cellular and molecular components of this response remain unknown. We sought to dissect the dynamic evolution of the tumor and CAR T cell interactions in a co-culture model with GBOs using single cell multi-modal analysis platform. We identified components of a closely interconnected network of cell-cell interactions that led to concomitant shifts in cellular states upon T cell activation. Unexpectedly, we also observed that the immunosuppressive tumor response coincided with the downregulation of glioma stem cell signatures in both antigen-positive and antigen-negative neoplastic cells. Soluble factors in the conditioned media from the co-cultures could recapitulate this phenotype, and we found that IFNɣ was required in this context, but it alone was not sufficient. These results indicate that the GBM stem cell like state could be influenced by immune activity and suggest a broader role for immunotherapies in the treatment of this disease.

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Available to all on Sunday, September 14, 2025

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