Developing a 3D Bioprinted Glioblastoma Multiforme Model in a Vasculated Environment
Introduction
Glioblastoma multiforme (GBM) is an aggressive and highly vasculated grade IV glioma primarily comprised of glioma stem-like cells (GSCs). Current in-vitro disease models cannot fully replicate the perivascular tumor niche given the lack of vasculature and extracellular matrix (ECM). Alternatively, current in vivo models are restricted by their high cost, time intensiveness, and slightly altered human disease responses in animal backgrounds. Therefore, we propose the development of a vasculated, 3D bioprinted GBM model to obtain in vivo-like results in an ex vivo setting.
Methods
Our model consists of GSC spheroids that represent either proneural or mesenchymal GBM subgroups, human brain replica ECM, and endothelial cells (ECs) lining a perfusable channel. Specifically, our methods include biomaterial synthesis, bioprinting, spheroid formation, qRT-PCR, immunofluorescent staining, cell seeding, spheroid encapsulation, and Western blot.
Results
After confirming that our GSCs retained their stemness, proliferation, hypoxia, and group-specific expressions as spheroids in the presence and absence of ECs, we observed that both GSC spheroids are prone to differentiation towards astrocytes and pericytes when in the presence of ECs. These results resemble other in vitro studies and serve as our controls. Our brain-mimicking ECM biomaterial was formulated to include gelatin and hyaluronan derivatives with a healthy brain stiffness of ~1 kPa. This starting condition for our model will potentially allow the GSCs to remodel the ECM in a physiologically relevant manner, ultimately increasing the stiffness to the diseased state of ~5 kPa. Notably, proneural GSC spheroids are more prone to sprouting in the ECM than the mesenchymal GSC spheroids after encapsulation and culturing beyond one month.
Conclusion
Future co-culturing of GSC spheroids and ECs in the bioprinted ECM should increase sprouting, differentiation, and expressions that trend more towards in vivo observations. The completed bioprinted model with perfusable EC channel should better replicate responses seen with in vivo models. Our goal is to use this model to study GBM biology, identify tumor specific dependencies, and perform high throughput drug screens.