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 tumours and are associated with poor survival. Currently, pHGG detection relies on 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 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. Analysis of EVs isolated from cell culture media confirmed the presence of these markers, along with other tumour-associated markers including targets of chimeric antigen receptor (CAR) T cell therapy. Taken together, our results showed that RG-derived EVs can be isolated and detected by the combination of markers, laying a groundwork for developing a novel EV-based biomarker for pHGGs.