Intranasal administration of stem cell-derived exosome alleviates cognitive impairment against subarachnoid hemorrhage

Introduction: Brain damage caused by subarachnoid hemorrhage (SAH) currently lacks effective treatment, leading to stagnation in the improvement of functional outcomes for decades. Recent studies have demonstrated the therapeutic potential of exosomes released from mesenchymal stem cells (MSC), which effectively attenuate neuronal apoptosis and inflammation in neurological diseases. Due to the challenge of systemic dilution associated with intravenous administration, intranasal delivery has emerged as a novel approach for targeting the brain. In this study, we investigate the effects of intranasally administered MSC-derived exosomes in a SAH animal model and elucidate their mode of action.

Methods: Exosomes were isolated from the cell supernatants of amnion-derived MSC. SAH was induced in 8-week-old Sprague-Dawley rats using an autologous blood prechiasmatic cistern injection model. A total of 1.2 × 10¹⁰ particles of exosomes in 200 μL of PBS or PBS alone were intranasally administered immediately and 24 h post-injury. Neurological function was assessed up to 7 days after injury, and histological analysis was performed to evaluate their anti-apoptotic and anti-inflammatory effects. The biodistribution of exosomes was assessed using PET/CT imaging of ⁶⁴Cu labeled exosome. In vitro analyses were performed using primary glial cells and cell lines to evaluate the anti-inflammatory effects of the exosomes.

Results: Animals treated with exosomes exhibited significant improvement in cognitive function compared with PBS treated animal. Apoptotic cells and inflammation were reduced for the exosome group in the hippocampal CA1 area and in cortex, resulting in better neuronal cell survival. Blood brain barrier permeability was also preserved in the exosome group. Nuclear imaging revealed that exosomes were primarily transferred to the olfactory nerve and cerebrum; furthermore, exosomes were also observed in the trigeminal nerve and brainstem, where exosomes were co-localized with microglia and with endothelial cells. In vitro assessment showed that exosome administration ameliorated inflammation and prevented the death of glial cells.

Conclusions: MSC-derived exosomes were successfully transferred into the brain through intranasal administration and alleviated brain damage following SAH.