Development of a novel extracellular vesicle-based biomarker approach for pediatric high-grade glioma

Pediatric high-grade gliomas (pHGGs) account for 20% of childhood brain tumors and are associated with poor survival rates. Currently, pHGG detection relies on Magnetic Resonance Imaging (MRI), a costly and time-consuming procedure. Extracellular vesicles (EVs) carry molecular markers indicative of their cellular origin and can be isolated from various biofluids, offering an alternative approach. Recent studies showed that pHGGs contain cells that molecularly and morphologically resemble radial glia (RG), a type of neural progenitor. Given that RGs are normally exclusive to the developing brain, we hypothesized that EVs secreted from RG-like glioma cells (RG-EV) serve as a pHGG biomarker. However, there are no established molecular markers to specifically detect RG-derived EVs. To address this, we first identified a combination of surface markers to differentiate EVs derived from RG-like glioma cells from those of non-RG cells. We next validated the expression of these markers in patient-derived cell lines. Our analysis of EVs showed that pHGG cells secrete a significantly higher proportion of RG-EV compared to human astrocytes (88.88 ± 7.69% vs 0.57 ± 0.28%; p < 0.0001), along with other tumor-associated markers, including targets of chimeric antigen receptor (CAR) T cell therapy such as disialoganglioside GD2 (73.46 ± 11.75% vs 0.32 ± 0.07%; p < 0.001). Taken together, our findings showed that RG-derived EVs can be specifically isolated and detected by the combination of markers, distinguishing pHGG cells from non-malignant astrocytes. This work establishes a basis for developing a novel EV-based diagnostic biomarker approach for pHGGs.