Abstract 181: Biomimetic, 3D hydrogels to investigate effects of microenvironment biophysical properties on patient-derived glioblastoma (GBM) and endothelial cells (ECs)
Authors: Sohrabi Alireza , Liang Jesse , Muthukrishnan Deepthi , Solomon Itay , Kim Carolyn , Lao Amelia , Kornblum Harley , Seidlits Stephanie 
Published: August 2018

Abstract
Introduction: This study investigated how the mechanical microenvironment of glioblastoma (GBM) tumors may affect morphology and phenotype of patient-derived GBM and brain endothelial cells (ECs)– both critical components in the perivascular invasive niche.
Materials and Methods: Hydrogels were fabricated from thiolated hyaluronic acid (HA-SH) (0.5 w/v%) and 4-arm PEG-SH (1.5 w/v%), 8-arm PEG-norbornene (1.125 w/v%). Gelation occurred upon exposure to UV light (365 nm, 3-5.75 mw/cm2) for 15 s in the presence of a cytocompatible photoinitiator LAP (Lithium Pehnyl (2, 4, 6-trimethylbenzoyl) phosphinate, 0.025 w/v%). Patient-derived gliomaspheres or single dissociated ECs were mixed with hydrogel precursors prior to gelation. Phase contrast images were acquired every 3 days to monitor cell migration. After 9 days, 3D cultures were fixed, and cells visualized with CellMaskTM Green (ThermoFisher) and Hoescht (nuclei). Cell survival following encapsulation was evaluated using a Live/Dead Assay (Life Technologies). A Leica LSP5 confocal microscope was used to image 3D cultures. Storage moduli (G') of hydrogels were measured using shear rheometer (TA DHR-2) with an 8-mm flat plate geometry.
Results and Discussion: Hydrogel stiffness (G') was controlled by varying UV intensity to achieve a range of 150-1500 Pa, which is representative of the normal brain and tumor microenvironments, respectively. Gliomaspheres and ECs cultured showed comparable survival 7 days post-encapsulation in both soft and stiff gels. Gliomaspheres cultured in stiff hydrogels remained did not migrate away from spheroids, while cells encapsulated in soft hydrogels exhibited robust migration. Our previous results showed that ECs residing in GBM perivasculature differentially express high amount of integrin-binding sialoprotein (IBSP). Survival of ECs in hydrogels baring different biophysical properties is an appropriate platform to study the effect of stiffness on ECs protein expression.
Conclusion: Patient-derived GBM and ECs were successfully cultured in 3D HA hydrogels mimicking biophysical properties of brain or GBM tumor tissue. GBM cells cultured in stiffer environments were unable to migrate, but upon culture in soft environments were found to migrate up to 200 µm away from seeded spheroids within 9 days of cultures.
Acknowledgment: This project is funded by NIH 1R21NS0931099-01A1 grant and University of California Cancer Research Coordinating Committee Research Award. NIH Training Grant in Genomic Analysis and Interpretation T32HG002536.
Citation Format: Alireza Sohrabi, Jesse Liang, Deepthi Muthukrishnan, Itay Solomon, Carolyn Kim, Amelia Lao, Harley Kornblum, Stephanie Seidlits. Biomimetic, 3D hydrogels to investigate effects of microenvironment biophysical properties on patient-derived glioblastoma (GBM) and endothelial cells (ECs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 181.