Abstract
Glioblastoma multiforme (GBM) is the most common primary and aggressive brain tumors in adults with extremely poor prognosis and limited treatment options. A major hallmark of GBM is the rapid and diffused infiltration of tumor cells into the surrounding healthy tissue that contribute to tumor recurrence and therapeutic resistance. However, existing in vitro cell culture or in vivo xenograft models inadequately recapitulate the inter-tumoral and intra-tumoral heterogeneity which are key features of GBM. For example, common oncogenic drivers of GBM such as epidermal growth factor receptor (EGFR) amplification and EGFRvIII mutation do not persist in traditional in vitro models due to selection pressures, thus requires exogenous overexpression. Alternatively, EGFR statuses can be maintained in xenografted mice, but implantation of the primary GBM cells into the flank is required to first establish the tumor prior to secondary injection into the brains. Recently, we have established a novel protocol for culturing GBM tissue as organoids (GBOs) directly from patient tumor resection that retain many distinct cell populations in vitro with high fidelity evidenced by histological, whole-exome, bulk and single cell RNA analyses. Compared to prolonged generation time of previously established in vitro and xenograft models, our methodology is robust for generating GBOs within 1–2 weeks from initial resection. In addition, these GBOs can be readily xenografted into the adult mouse brains as an intact organoid, exhibit rapid and aggressive infiltration phenotypes, and maintains driver mutation EGFRviii within as little as one month. Consequently, they can be used to test in vivo treatment efficacies in a timely fashion. The presence of diverse cell types in this GBO model offers a promising platform for not only understanding of tumor biology, but also more strategic development of new therapies.