TAT and RVG Co-modified MSC-derived Exosomes-mediated Delivery of microRNA-15b-5p Inhibitor Alleviate Cerebral Ischemia and Reperfusion-induced Neuronal Apoptosis by Promoting HTR2C-ERK Signaling.

Neuronal apoptosis significantly contributes to brain damage in cerebral ischemia and reperfusion (I/R) injury, posing a serious threat to human health and lacking effective treatment. MicroRNA-15b-5p (miR-15b-5p) was previously reported to be significantly elevated in serum exosomes from ischemia patients and in freshly excised human stroke brain tissue. However, how miR-15b-5p regulates neuronal death in cerebral I/R injury remains elusive. In addition, we propose that encapsulating the miR-15b-5p inhibitor in TAT and RVG co-modified mesenchymal stem cell-derived exosomes (TAT&RVG-Exo + miR-15b-5p inhibitor) could serve as an effective treatment for cerebral I/R injury. This study utilized a mouse model of intraluminal middle cerebral artery occlusion/reperfusion (MCAO/R) and HT22 hippocampal neuronal cells exposed to oxygen-glucose deprivation and reoxygenation (OGD/R) to simulate cerebral I/R injury. The impact of miR-15b-5p on neuronal death in cerebral I/R injury and its underlying mechanisms were investigated through bioinformatic analysis, qRT-PCR, Western blotting, immunofluorescent staining, flow cytometry, luciferase reporter assay, and RNA-Fluorescence in situ hybridization. Exosomes derived from MSCs were isolated and characterized using transmission electron microscopy and nanoparticle flow cytometer. Through surface modification and sonication, TAT-peptide and RVG-peptide co-decorated MSC-Exos carrying miR-15b-5p inhibitor (TAT&RVG-Exo + miR-15b-5p inhibitor) were prepared. The protective effects of TAT&RVG-Exo + miR-15b-5p inhibitor on cerebral I/R injury were evaluated using biodistribution imaging system, TTC staining, Western blotting and immunofluorescent staining. In cerebral I/R injury, both in vivo and in vitro, miR-15b-5p expression was significantly elevated, and its inhibition notably reduced neuronal apoptosis. Our findings indicate that miR-15b-5p enhances OGD/R-induced neuronal apoptosis through the HTR2C-ERK signaling pathway. TAT&RVG-Exo + miR-15b-5p inhibitor demonstrated enhanced ability to traverse the BBB and target the peri-infarct region in cerebral I/R injured mice, exhibiting superior protective effects against cerebral I/R injury. TAT and RVG co-modified MSC-derived exosomes-mediated delivery of microRNA-15b-5p inhibitor alleviate cerebral I/R-induced neuronal apoptosis by promoting HTR2C-ERK signaling, which offers a potentially effective new treatment for cerebral I/R injury.