Pericyte-induced Chemoresistance in Patient-derived Glioblastoma Models for Personalized Medicine

Introduction: Pre-clinical in vitro models using patient-specific glioblastoma (GBM) allow chemotherapeutic drug sensitivity testing for personalized medicine applications. However, reliable models that recapitulate the complex mechanisms of chemoresistance driven by the GBM tumor microenvironment remain to be validated in a patient-specific manner, particularly pericyte-induced chemoresistance mediated by the CCL5-CCR5 paracrine axis. This study aimed to assess and validate the impact of pericytes on inter- and intra-tumoral TMZ chemoresistance heterogeneity.

Methods: Patient-derived GBM cells were isolated from two patients with grade IV tumors. For each patient, GBM cells were isolated from two distinct tumor regions. To evaluate Temozolomide (TMZ) sensitivity, GBM cells (QNS89WT-1C, -1D, -3C, -3D), cultured with or without primary pericytes, were treated with 0, 200, and 800 µM TMZ for 72 hours. GBM cell viability was measured using metabolic activity (Presto Bleu), viability (Live/Dead staining, flow cytometry: Zombie violet), and cell proliferation (flow cytometry: CFSE).

Results: In mono-culture, 72 hours of TMZ treatment decreased metabolic activity (Presto Blue) of all GBM cells compared to controls, with 3C cells (core) most sensitive to TMZ, followed by 3D, 1D, and 1C. TMZ decreased viability (Live/Dead staining) of all GBM cells compared to controls, with 1D and 3D cells (margin) showing a 30% decrease, 3C cells 17%, and 1C cells 8%. Proliferation (CFSE) of 1C, 1D, and 3C cells reduced with TMZ but increased for 3D cells. In co-culture, TMZ affected viability and proliferation, decreasing viability of 1C and 3C cells and increasing 1D and 3D cells. Proliferation of 1C and 3C increased but reduced for 1D and 3D. Pericytes induced inter- and intra-tumoral TMZ chemoresistance heterogeneity, with dose-dependent discrepancies between outcome measures.

Conclusion : Patient-derived GBM in vitro models assess pericyte-induced chemoresistance and TMZ sensitivity heterogeneity. Pericytes' presence and TMZ sensitivity measurement methods are crucial for clinical translation in GBM treatment.