Glioblastoma (GBM) Organoids

Glioblastoma Pathology and Preclinical Limitations

Glioblastoma Multiforme (GBM) is the most common and aggressive primary brain malignancy in adults, characterized by rapid growth, genomic instability, and diffuse infiltration into the surrounding healthy brain parenchyma. Despite surgical resection, radiotherapy, and temozolomide chemotherapy, the median survival rate for GBM patients remains less than 15 months. A major driver of this treatment resistance is the cellular heterogeneity of the tumor, which is maintained by a subpopulation of highly resistant Glioblastoma Stem Cells (GSCs).

Preclinical development of new therapeutics has been hampered by the limitations of traditional models. Two-dimensional cell lines cultured on plastic substrates fail to replicate the hypoxic zones and cell-matrix interactions that maintain GSC niches. Animal models, such as orthotopic xenografts in mice, are expensive, slow, and show species-specific differences in drug uptake and brain tissue organization. The development of human-derived GBM organoids provides a predictive, high-throughput platform that preserves the genomic profile and cellular heterogeneity of the patient's original tumor.

Cultivation of Patient-Derived Glioblastoma Organoids

The establishment of patient-derived GBM organoids begins with the acquisition of surgically resected tumor tissue. The specimen is processed immediately under sterile conditions to preserve viability. The tissue is subjected to mechanical slicing and enzymatic digestion to generate small cell clusters, which are then cultured in serum-free media containing neural stem cell growth factors (EGF and FGF2) and B27 supplement.

Culturing the cells in the absence of serum is critical: exposure to serum forces GSCs to differentiate, causing the loss of the tumor stem cell population and the phenotypic characteristics of the patient's original tumor. In suspension culture, these cell clusters self-assemble into three-dimensional organoids within 10 to 14 days.

Genomic profiling (including next-generation sequencing and RNA-seq) confirms that these organoids retain the key genetic driver mutations (such as EGFR amplification, PTEN deletion, and TP53 mutation) and the transcription subtypes (proneural, classical, mesenchymal) of the parental tumor. This genomic fidelity makes GBM organoids suitable for personalized oncology screening.

Co-Culture Invasion Assays and Motility Inhibition

Glioblastoma multiforme (GBM) is characterized by diffuse infiltration into adjacent neural tissues. By culturing GBM organoids alongside cerebral organoids (co-culture invasion assays), researchers observe tumor migration routes in real time.

To model this invasive behavior in vitro, we utilize co-culture invasion assays. Glioblastoma organoids are labeled with a green fluorescent protein (GFP) tag, while healthy cerebral organoids are labeled with a red fluorescent protein (RFP) tag. The tumor organoids are placed in direct contact with the healthy cerebral tissue, and the co-culture is monitored using high-resolution confocal microscopy over several days.

During the assay, GFP-labeled glioblastoma cells invade the healthy cerebral tissue, forming cellular networks called tumor microtubes. These microtubes serve as conduits for signaling, nutrient transport, and invasive migration, allowing the tumor cells to infiltrate the healthy tissue. By analyzing these migration routes, researchers can evaluate the efficacy of experimental therapeutics designed to inhibit cell motility, focal adhesion kinases, or matrix metalloproteinases (MMPs).

Blood-Brain Barrier (BBB) Microfluidic Modeling

A major challenge in brain tumor therapeutics is the blood-brain barrier (BBB), which prevents more than 98% of small-molecule drugs and nearly 100% of large-molecule drugs from entering the brain parenchyma.

To evaluate the BBB penetration of experimental therapeutics, the BioFoundry integrates GBM organoids with microfluidic blood-brain barrier models. These organ-on-a-chip devices consist of parallel fluidic channels separated by a semi-permeable membrane. The vascular channel is lined with human brain microvascular endothelial cells, while the brain channel contains astrocytes, pericytes, and the target glioblastoma organoid.

The endothelial cells form tight junctions that restrict transport, creating a physical barrier. By introducing candidate drugs into the vascular channel and measuring their concentration in the brain channel via mass spectrometry, we can quantify BBB penetration rates. Simultaneously, we can evaluate the cytotoxic impact of the drug on the glioblastoma organoid. This integrated platform helps developers identify candidates that can cross the BBB and target the invasive tumor cells without causing toxic effects on healthy brain tissue.