Bioengineered Scaffolds for 3D Analysis of Glioblastoma Proliferation and Invasion

The invasion of malignant glioblastoma (GBM) cells into healthy brain is a primary cause of tumor recurrence and associated morbidity. Here, we describe a high-throughput method for quantitative measurement of GBM proliferation and invasion in three-dimensional (3D) culture. Optically clear hydrogels composed of thiolated hyaluronic acid and gelatin were chemically crosslinked with thiol-reactive poly(ethylene glycol) polymers to form an artificial 3D tumor microenvironment. Characterization of the viscoelasticity and aqueous stability indicated the hydrogels were mechanically tunable with stiffness ranging from 18 Pa to 18.2 kPa and were resistant to hydrolysis for at least 30 days. The proliferation, dissemination and subsequent invasion of U118 and U87R GBM spheroids cultured on the hydrogels were tracked in situ with repeated fluorescence confocal microscopy. Using custom automated image processing, cells were identified and quantified through 500 µm of gel over 14 days. Proliferative and invasive behaviors were observed to be contingent on cell type, gel stiffness, and hepatocyte growth factor availability. These measurements highlight the utility of this platform for performing quantitative, fluorescence imaging analysis of the behavior of malignant cells within an artificial, 3D tumor microenvironment.