Study of oncolytic virus on an in vitro model of glioblastoma developed in brain organoid

Author(s)

Rodolfo Sanches Ferreira

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2022-12-19

Examining board members

Oswaldo Keith Okamoto; Patricia Cristina Baleeiro Beltrao Braga; Merari de Fatima Ramires Ferrari; Tiago Góss dos Santos

• Advisor: Oswaldo Keith Okamoto

Abstract

Cancer is one of the main causes of death worldwide, and central nervous system (CNS) cancers have great clinical relevance since they are responsible for high rates of morbidity and mortality. Glioblastoma (GBM), the adult diffuse glioma with worst prognosis, is the most common CNS tumor in adults and causes thousands of deaths annually. The treatments currently used result in an average overall survival of only 12 to 15 months, a fact that emphasizes the need for new therapeutic strategies against GBM. Recently, studies have found that the Zika virus (ZIKV) has a relevant oncolytic effect against CNS tumors, including GBM, but additional data on its efficacy and safety are needed. The heterogeneous histological pattern, the simultaneous presence of different cell types and the multiple tumor-microenvironment interactions of CNS tumors emphasize the need for adequate GBM in vitro models. The application of human organoids models on cancer research has proved to be a valuable strategy for testing new therapeutic approaches. In this context, our work sought to evaluate the ZIKV oncolytic effect on different GBM cell lines, compared to embryonic CNS tumors cell lines, co-cultured with brain organoids derived from stem cells, evaluating viral selectivity between normal and transformed cells. Our organoids showed characteristic tissue organization and cellular composition similar to developing brain layers. The hybrid co-culture models provided a three-dimensional cellular environment that allowed tumor cells interaction with neural tissue. Adhesion and dispersion of tumor cells were observed within the initial 72 hours of co-culture. All tumor strains used were able to invade the interior of the organoid tissue within two weeks. ZIKV infection of co-cultured models led to a significant reduction in tumor cells proportion in two GBM strains evaluated, LN18 one-week post-infection and U343-MG two-weeks post-infection, and in the Medulloblastoma strain USP13 two weeks after infection. ZIKV quantification showed significantly higher viral copies in organoids containing tumor cells compared to isolated control organoids. Our findings emphasize brain organoids fitness for CNS tumors analysis in vitro. The application of ZIKV in the co-culture model led to viral infection and replication, causing an oncolytic effect in GBM and Medulloblastoma cells. Future studies with in vitro and in vivo models of GBM are needed to explore ZIKV antitumor capacity and assist in the development of new therapeutic strategies against aggressive CNS tumors. (AU)

• FAPESP's process: 19/27784-8 - Study of oncolytic virus on an in vitro model of glioblastoma developed in brain organoid
• Grantee: Rodolfo Sanches Ferreira
• Support Opportunities: Scholarships in Brazil - Master