Development and characterization of an on-chip glioma outgrowth model

Abstract Tumour recurrence in high-grade gliomas, such as glioblastoma, is extremely common due to the challenges associated with complete surgical removal. Approximately 95% of glioblastoma tumours recur within 2 cm of the tumour resection margin; however, unfortunately, the current clinical measurement techniques do not accurately capture cell state during critical stages of recurrence. The development of in vitro models for investigating glioblastoma recurrence outgrowth can inform further understanding of the mechanistic underpinnings of this process at a cellular level. This work presents the development of an on-chip in vitro platform which can be used to assess glioblastoma interactions with healthy neural cells. Using a custom single-channel multi-well microfluidic system, spheroids of GFP transfected rat glioma cells were co-cultured together with rat astrocytes to investigate differences in glioblastoma outgrowth between co-culture and monoculture (i.e. glioma only, or astrocyte only). Quantitative image analysis demonstrated significantly increased outgrowth of glioma cells from spheroids in co-culture compared to monoculture. Additionally, comparison of upregulation of markers associated with glioma aggressiveness (CD44) and astrocyte reactivity (glial fibrillary acidic protein) showed significant differences in cellular expression between the cells in co-culture and monoculture configurations. These findings align with existing literature suggesting that astrocytes facilitate a supportive environment for glioblastoma cells to proliferate and invade healthy tissue by changing to a reactive phenotype. Overall, this work presents a promising on-chip in vitro model that has the potential to aid in the quantification of glioblastoma invasion through directional control of outgrowth and offers the potential for the addition of complexities to more accurately model the glioblastoma neural cell microenvironment.