Islet-1 Mesenchymal Stem Cells-Derived Exosome-Incorporated Angiogenin-1 Hydrogel for Enhanced Acute Myocardial Infarction Therapy.

Although stem cell-derived exosomes have been recognized as new candidates for cell-free treatment in myocardial infarction (MI), the challenge to improve the exosome retention in ischemic tissue remains. Our previous research indicated that islet-1(ISL1) overexpression enhances the paracrine function of mesenchymal stem cells (MSCs) and promotes angiogenesis in a model of MI. In this study, genetically engineered ISL1-MSC-derived exosomes (ISL1-MSCs-Exo) were collected, and the contents were analyzed by exosomal RNA sequencing. Next, we investigated if ISL1-MSCs-Exo could exert therapeutic effects and their incorporation into a new angiogenin-1 hydrogel (Ang-1 gel) could boost the retention of exosomes and further enhance their protective effects. Our results demonstrated that ISL1-MSCs-Exo could play a therapeutic role in vitro and in vivo, which might be due to changed exosomal contents. Ang-1 gel increased the retention and enhanced the anti-apoptosis, proliferation, and angiogenic capacity of ISL1-MSCs-Exo in endothelial cells. Echocardiography revealed that Ang-1 gel significantly augment the therapeutic effects of ISL1-MSCs-Exo for MI. The main mechanism might result from increased retention of ISL1-MSCs-Exo, herein enhanced pro-angiogenetic effects in an ischemic heart. Taken together, our findings indicated that ISL1-MSCs-Exo had endothelium-protective and pro-angiogenic abilities alone and Ang-1 gel could notably retain ISL1-MSCs-Exo at ischemic sites, which improved the survival and angiogenesis of endothelial cells and accelerated the recovery of MI. These results not only shed light on the therapeutic mechanism of ISL1-MSCs-Exo incorporated with Ang-1 gel but also offer a promising therapeutic option for ischemic disease.