3D-cultured BMSC exosomes improve cerebral ischemia/reperfusion injury-induced neuronal apoptosis by regulating the microglia polarization

Microglial activation is a key driver of neuroinflammation following cerebral ischemic reperfusion injury (CIRI). Exosomes (Exo) derived from bone marrow mesenchymal stem cells (BMSCs) can regulate microglia, causing a transition from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, thereby reducing neuronal apoptosis in post-reperfusion injuries. However, the generation of superior-quality exosomes remains a significant hurdle in this field. We performed three-dimensional (3D) cultivation of BMSCs using a gelatin methacryloyl (GelMA) hydrogel and collected the released exosomes. We conducted experiments using lipopolysaccharide (LPS)-induced BV2 cells, oxygen-glucose deprivation/reoxygenation (OGD/R)- induced HT22 cells, and CIRI mice to verify the effects of 3D-cultured exosomes in regulating microglial activation and alleviating neuronal apoptosis. Based on the cellular and animal experiments, we successfully demonstrated the remarkable efficacy of exosomes derived from 3D-cultured BMSC using a GelMA hydrogel in the context of CIRI. These exosomes effectively mitigated the conversion of microglia to the inflammatory phenotype and facilitated their transition to the anti-inflammatory phenotype, thereby reducing aseptic inflammatory reactions and neuronal apoptosis. This study demonstrated the effectiveness of GelMA-based 3D-cultured exosomes in treating CIRI and introduced innovative concepts and opportunities for addressing this condition with clinical applications.