间充质干细胞来源的外泌体作为新型ncRNA靶向载体治疗心梗的策略及机制研究

心梗是人类致死致残的主要原因，无有效疗法。近期，细胞间信使外泌体移植治疗心梗备受研究者关注。我们发现敲除脐带间充质干细胞的免疫抗原B2M后，将其外泌体注射到心梗动物模型，能更有效地恢复心功能，且是由外泌体内ncRNA介导。基于此，申请人提出了“外泌体母系印记”理论，于2017年发表在Nature Reviews Cardiology杂志。研究内容：1)利用CRISPR技术清除母代细胞免疫排斥等印记，以期得到富含心梗治疗相关ncRNA的外泌体；2）用噬菌体展示技术体内筛选靶向心肌细胞的归巢肽，用基因工程技术改造干细胞，使其外泌体表达归巢肽，确保外泌体的心肌靶向性；3）用复合多肽纳米纤维胶包封外泌体，提高其在心梗区的驻留率；4）用siRNA、慢病毒过表达等多重策略，阐明外泌体中ncRNA治疗心梗的具体机制。本研究旨在为干细胞来源的外泌体作为新型ncRNA靶向载体治疗心梗提供实验数据和理论基础。

Myocardial infarction is a major cause of mortality and morbidity,and there is no effective treatment. Recently, the transplantation of exosomes, which function as cellular messengers, has emerged as a potential approach for the treatment of several devastating diseases. We found that exosomes derived from mesenchymal stem cells with β2-microglobulin knockout restore cardiac function in a myocardial infarction model, and the effects are mediated by non-coding RNA (ncRNA). Based on these findings, the applicant proposed an exosome imprinting theory, published in Nature Reviews Cardiology in 2017. In this grant application, we propose the following studies: 1) To eliminate the immunogenic imprint from parent cells using CRISPR technology in order to obtain exosomes enriched in ncRNAs with therapeutic potential; 2) To identify cardiac homing peptides using the phage display technique and express these peptides in exosomes via genetic engineering of stem cells; 3) To prolong exosome retention in infarcted hearts by encapsulating the exosomes in composite polypeptide nanofiber gel; and 4) To delineate the precise mechanisms by which exosome-derived ncRNAs exert their therapeutic effects, using small-interfering RNA-based gene silencing and lentivirus-based gene overexpression. The goal of this study is to provide both an experimental and a theoretical basis for stem cell-derived exosomes as novel ncRNA carriers targeting the heart and for the treatment of myocardial infarction.