Engineered Exosomes Containing microRNA-29b-2 and Targeting the Somatostatin Receptor Reduce Presenilin 1 Expression and Decrease the β-Amyloid Accumulation in the Brains of Mice with Alzheimer’s Disease

En-Yi Lin,1,2 Shao-Xi Hsu,1 Bing-Hua Wu,1 Yu-Chen Deng,1,3 Wei Wuli,1 Yuan-Sheng Li,3 Jui-Hao Lee,3 Shinn-Zong Lin,2,4 Horng-Jyh Harn,2,5 Tzyy-Wen Chiou1 1Department of Life Science and Graduate Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan; 2Bioinnovation Center, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan; 3Everfront Biotech Inc, Taipei, Taiwan; 4Department of Neurosurgery, Hualien Tzu Chi Hospital, Hualien, Taiwan; 5Department of Pathology, Hualien Tzu Chi Hospital, Hualien, TaiwanCorrespondence: Tzyy-Wen Chiou, Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Road, Shou-Feng, Hualien, Taiwan, Tel +886-3-890-3638, Email twchiou@gms.ndhu.edu.tw Horng-Jyh Harn, Department of Pathology, Hualien Tzu Chi Hospital, Hualien, Taiwan, Tel +886-3-856-1825, Email arthewduke@gmail.comPurpose: Exosomes are membrane vesicles secreted by various cells and play a crucial role in intercellular communication. They can be excellent delivery vehicles for oligonucleotide drugs, such as microRNAs, due to their high biocompatibility. MicroRNAs have been shown to be more stable when incorporated into exosomes; however, the lack of targeting and immune evasion is still the obstacle to the use of these microRNA-containing nanocarriers in clinical settings. Our goal was to produce functional exosomes loaded with target ligands, immune evasion ligand, and oligonucleotide drug through genetic engineering in order to achieve more precise medical effects.Methods: To address the problem, we designed engineered exosomes with exogenous cholecystokinin (CCK) or somatostatin (SST) as the targeting ligand to direct the exosomes to the brain, as well as transduced CD47 proteins to reduce the elimination or phagocytosis of the targeted exosomes. MicroRNA-29b-2 was the tested oligonucleotide drug for delivery because our previous research showed that this type of microRNA was capable of reducing presenilin 1 (PSEN1) gene expression a