Medical Student University of California, Los Angeles Los Angeles, California, United States
Introduction: Glioblastoma (GBM) is one of the most common and most lethal types of brain cancer. Treatment development is limited by the cost, time, reproducibility, and complexity inherent to all in vivo models, and by the inability of current in vitro models to capture the hallmark genetic heterogeneity of GBM. Furthermore, some GBM cell lines cannot be maintained in vitro at all, thereby posing a significant challenge to high-throughput drug testing for personalized medicine.
Methods: Our lab has developed a 3D tissue-engineered model in which GBM cells are cultured in scaffolds of hyaluronic acid, an extracellular matrix component that is abundant in normal brain tissues, overexpressed in GBM, missing in the current gold standard in vitro model (gliomaspheres in suspension culture), but known to promote tumor growth, invasion, and therapeutic resistance. To test the fidelity of our scaffold in recapitulating various characteristics of the original patient tumor, we are analyzing cellular proliferation and heterogeneity using immunocytochemistry, flow cytometry, and single-cell RNA sequencing.
Results: We have thus far tested three patient-derived xenografts that did not survive in suspension culture, but survived in 3D scaffold culture. We next investigated if survival was due to increased cellular proliferation and/or decreased apoptosis. Flow cytometry data comparing a sphere-failing and a sphere-forming line appear to rule out scaffold-driven increases in cellular proliferation, while apoptosis studies are in progress. Meanwhile, sequencing of a fourth cell line showed an ability of scaffold cultures to retain CD68+ macrophages that were found in the original tumor, but were absent in the patient-matched orthotopic xenograft, thereby suggesting an ability to maintain at least one aspect of the immune system not previously possible in other models.
Conclusion : Our preliminary results suggest that the scaffold provides a microenvironment that is more conducive to maintaining patient-derived GBM cells in culture when compared to other models.
