ABSTRACT Cranial radiation therapy (RT) with concomitant and adjuvant temozolomide (TMZ; Stupp protocol) prolongs glioma survival but frequently results in persistent cognitive impairment. Human neural stem cell (hNSC)-derived extracellular vesicles (EVs) are a promising acellular therapy whose bioactive cargo can modulate neuroinflammation and synaptic integrity. We evaluated two EVs derived from GMP-grade hNSCs (Shef6 and UCI-191) in syngeneic glioma-bearing and non-tumor adult mice treated with fractionated cranial RT (3 × 8.67 Gy) together with concomitant low-dose (25 mg/kg) and adjuvant high-dose (66.7 mg/kg, intraperitoneal) TMZ. EV administration improved memory performance in RT-TMZ–exposed mice and, notably, Shef6-EVs also extended survival in glioma-bearing mice in the absence of chemoradiotherapy. Immunofluorescence analyses demonstrated attenuated gliosis and preservation of synaptic integrity in EV-treated RT-TMZ-exposed brains, while bulk transcriptomic profiling identified distinct neuroprotective gene expression pathways associated with each EV source. Critically, neither Shef6 nor UCI-191 EVs diminished or interfered with the anti-tumor efficacy of RT-TMZ. These data support hNSC-derived EVs as a translational strategy to mitigate treatment-related neurotoxicity while preserving oncologic benefit in a clinically relevant glioma model. • Systemic administration of GMP-grade hNSC-EVs after RT-TMZ restores cognitive performance in both non-tumor and glioma-bearing mice. • hNSC-EV treatment attenuates astrogliosis and microglial activation and preserves synaptic density in brain regions critical for learning and memory. • hNSC-EVs do not compromise the anti-tumor efficacy of RT-TMZ, as tumor control and survival are maintained in glioma-bearing animals. • Peripheral organ histology shows no gross toxicity following repeated systemic EV administration. • Transcriptomic profiling reveals distinct but convergent neuroimmune and neuroprotective gene-expression programs engaged by each EV line, consistent with the observed rescue of cognition and synaptic integrity.
Hudson et al. (2026) studied this question.