Abstract 3845: A matching panel of tumor organoids and patient derived orthotopic xenograft mouse models (PDOX) of high-grade gliomas in EGFP-based SCID mice

Background: High grade glioma, also known as glioblastoma multiform (GBM) a highly aggressive brain tumor, requires advanced systems to study tumor-stroma interactions. Paired in vitro and in vivo model systems such as 3D organoids and PDOX models derived from EGFP-SCID mice offered a unique opportunity to precisely and rapidly differentiation of mouse (EGFP positive) from human tumor cells, thereby facilitating the visualization and analysis of tumor/normal cell interactions in vitro and in vivo. Methods: EGFP-SCID mice received intra-cranial implantation of pediatric (n=6) and adult (n=6) GBM tumors to form PDOX. Tumor-bearing mouse brains were dissected, and tumor cells were cultured to generate organoids by seeding at cell densities of 1250, 2500, 5000 cells/well and monitored for size and count over 1-21 or 28 days. Immunohistochemistry (IHC) tracked the distribution of EGFP-positive mouse cells and GBM markers, including GFAP, Nestin, Ki67, GFP, CD276+ and so on. Additional staining for lysosomes and nuclei (Hoechst/DIPA) confirmed cellular localization and interactions. Results: Hybrid organoids were successfully generated, integrating mouse and human GBM cells in 12 PDOX models. Organoid size and count varied by cell density and culture duration, with similar growth patterns between pediatric and adult samples. IHC confirmed expression of cellular proliferation (Ki67), glial cells (GFAP), differentiation (SYN), stem cell (Nestin) as well as normal mouse cells (GFP) that were in and surrounding tumor cells. In organoids, EGFP fluorescence revealed dynamic tumor-stroma interactions, with changing proportions of mouse cells and GBM cells over time, reflecting the organoid’s developmental complexity. Conclusion: This EGFP-based organoid and PDOX model system offers a robust platform for studying tumor-stroma interactions and characterizing cellular dynamics in GBM. The system’s integration of IHC provides a detailed view of tumor and stromal components, making it a valuable tool for biological and translational GBM studies. Citation Format: Xin (Alice) Zhai, Milagros Suarez Palacios, Zilu Huang, Jinnan Chen, Tongchao Jiang, Nitin Wadhwani, Michael DeCuypere, Yuchen Du, Xiaonan Li. A matching panel of tumor organoids and patient derived orthotopic xenograft mouse models (PDOX) of high-grade gliomas in EGFP-based SCID mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3845.