Biomanufacturing of glioblastoma organoids exhibiting hierarchical and spatially organized tumor microenvironment via transdifferentiation.

Glioblastoma (GBM) is the most aggressive type of brain tumor that originates from glioblastoma stem cells (GSCs). In the brain, GSCs are supported by a tumor microenvironment (TME) residing in the perivascular niche and the hypoxic niche. The GBM TME is highly heterogenous and exhibits complex cell-to-cell interactions. Three-dimensional tumorspheres cultured in stem cell-enriching media is often used as an in vitro model. The GBM tumorspheres retain some of the transcriptional and translational GSC features but often fails to recapitulate intertumor heterogeneity. Here, we developed a simple, matrix-free, and in vivo-like GBM organoids (GBOs) using patient-derived xenograft GBM lines in small-scale bioreactors. Shear stress was optimized to produce highly reproducible GBOs over 1 mm diameter within 4-5 weeks. GBOs exhibited high stemness and strong cell-to-cell interactions compared to conventional tumorsphere cultures. They displayed spatial gradients of hypoxia-inducible factor 1α positive hypoxic cores where CD133-positive cells resided and spatially heterogeneous expression of NOTCH and its ligands. We also observed a self-established, hierarchically organized, and heterogeneous TME by GBM transdifferentiation into endothelial cells, pericytes, and astrocytes. Collectively, we demonstrate the ability to biomanufacture uniformly sized GBOs that recapitulate in vivo GBM TME features that can serve as an improved GBM in vitro model.