Standardized Workflow for the Generation of Patient-Derived Glioblastoma Spheroids.

Glioblastoma (GBM) is one of the most aggressive and therapy-resistant primary brain tumors, mainly due to its pronounced intratumoral heterogeneity and highly invasive phenotype. Patient-derived three-dimensional (3D) culture models, including tumor spheroids, represent valuable tools to preserve the cellular complexity, phenotypic plasticity, and microenvironmental features of GBM ex vivo. However, standardized and reproducible protocols for the generation and maintenance of GBM spheroids from surgical specimens are still limited. Here, we describe a detailed and robust protocol for the isolation, 3D cultures, and expansion of primary GBM cells obtained from patient biopsies, leading to the formation of stable and morphologically consistent spheroids. The protocol provides step-by-step instructions for tissue dissociation, cell seeding under low-adhesion conditions, optimization of culture density, and long-term spheroid maintenance. In addition, we include guidelines for the morpho-phenotypical characterization of the resulting 3D structures. This methodological workflow offers a reproducible platform for modeling GBM in vitro, enabling the study of tumor biology and supporting translational applications such as drug screening, biomarker validation, and patient-specific therapeutic testing in a 3D context.