Visualization and Identification of Bioorthogonally Labeled Exosome Proteins Following Systemic Administration in Mice

Platelet Membrane and miR-181a-5p Doubly Optimized Nanovesicles Enhance Cardiac Repair Post-Myocardial Infarction through Macrophage Polarization

Macrophages play a crucial role in cardiac remodeling and prognosis after myocardial infarction (MI). Our previous studies have built a scalable method for preparing scaled stem cell nanovesicles (NVs) and demonstrated their remarkable reparative effects on ischemic heart disease. To further enhance the targeted reparative capabilities of the NVs toward injured myocardium, we employed a dual modification strategy involving platelet membrane coating and miR-181a-5p loading, creating a nanovesicle termed P-181-NV. This study aimed to investigate the efficacy of P-181-NV in targeted reparative interventions for damaged myocardium and to reveal the underlying mechanisms involved. After successful construction and characteristic analysis of P-181-NV, the in vivo tracking techniques demonstrated a significant enhancement in the targeting capacity of P-181-NV toward the injured myocardium. Moreover, P-181-NV showed marked improvements in cardiac function and remodeling as observed through ultrasound echocardiography and Masson's trichrome staining. Furthermore, P-181-NV significantly augmented myocardial cell viability, angiogenic potential, and the polarization ratio of the anti-inflammatory macrophages. The findings of this study underscore the pivotal role of platelet-membrane-coated and miR-181a-5p modified stem cell nanovesicles in facilitating postmyocardial infarction cardiac repair. By modulating macrophage polarization, P-181-NV offers a promising approach for enhancing the efficacy of targeted reparative interventions for damaged myocardium. These results contribute to our understanding of the potential of nanovesicles as therapeutic agents for cardiac repair and regeneration, presenting avenues for future research and clinical applications.

Cell-Type-Specific Protein Metabolic Labeling and Identification Using the Methionine Subrogate ANL in Cells Expressing a Mutant Methionyl-tRNA Synthetase

The study of protein homeostasis in vivo is crucial for our understanding of the functions of cells and organisms. However, complex organisms, such as mammals, are built from heterogeneous tissues and cell-types. These cell-types are often specialized and react in different ways to the same physiological or pathological stimulus. Therefore, a major challenge in proteomics is the identification of proteomes and their behavior in a cell-type-specific manner. In this protocol, we describe a technique to label, enrich, and identify proteins from specific cell types. This technique is based on the expression of a mutant methionyl-tRNA synthetase (MetRS*) for incorporation of a bioorthogonal analog of methionine (ANL) into proteins. ANL can be subsequently bound to an alkyne by click-chemistry, which is used as a bait for protein purification followed by mass spectrometry identification.

Engineered exosomes for tissue regeneration: from biouptake, functionalization and biosafety to applications

Exosomes are increasingly recognized as important effector molecules that regulate intercellular signaling pathways. Notably, certain types of exosomes can induce therapeutic responses, including cell proliferation, angiogenesis, and tissue repair. The use of exosomes in therapy is a hot spot in current research, especially in regenerative medicine. Despite the therapeutic potential, problems have hindered their success in clinical applications. These shortcomings include low concentration, poor targeting and limited loading capability. To fully realize their therapeutic potential, certain modifications are needed in native exosomes. In the present review, we summarize the exosome modification and functionalization strategies. In addition, we provide an overview of potential clinical applications and highlight the issues associated with the biosafety and biocompatibility of engineered exosomes in applications.

Nanoengineering facilitating the target mission: targeted extracellular vesicles delivery systems design

Precision medicine has put forward the proposition of "precision targeting" for modern drug delivery systems. Inspired by techniques from biology, pharmaceutical sciences, and nanoengineering, numerous targeted drug delivery systems have been developed in recent decades. But the large-scale applications of these systems are limited due to unsatisfactory targeting efficiency, cytotoxicity, easy removability, and instability. As such, the natural endogenous cargo delivery vehicle-extracellular vesicles (EVs)-have sparked significant interest for its unique inherent targeting properties, biocompatibility, transmembrane ability, and circulatory stability. The membranes of EVs are enriched for receptors or ligands that interact with target cells, which endows them with inherent targeting mission. However, most of the natural therapeutic EVs face the fate of being cleared by macrophages, resulting in off-target. Therefore, the specificity of natural EVs delivery systems urgently needs to be further improved. In this review, we comprehensively summarize the inherent homing mechanisms of EVs and the effects of the donor cell source and administration route on targeting specificity. We then go over nanoengineering techniques that modify EVs for improving specific targeting, such as source cell alteration and modification of EVs surface. We also highlight the auxiliary strategies to enhance specificity by changing the external environment, such as magnetic and photothermal. Furthermore, contemporary issues such as the lack of a gold standard for assessing targeting efficiency are discussed. This review will provide new insights into the development of precision medicine delivery systems.

Reporter Systems for Assessments of Extracellular Vesicle Transfer

Extracellular vesicles (EVs) are lipid bilayer particles naturally released from most if not all cell types to mediate inter-cellular exchange of bioactive molecules. Mounting evidence suggest their important role in diverse pathophysiological processes in the development, growth, homeostasis, and disease. Thus, sensitive and reliable assessments of functional EV cargo transfer from donor to acceptor cells are extremely important. Here, we summarize the methods EV are labeled and their functional transfer in acceptor cells are evaluated by various reporter systems.

Extruded Mesenchymal Stem Cell Nanovesicles Are Equally Potent to Natural Extracellular Vesicles in Cardiac Repair

Mesenchymal stem cells (MSCs) repair injured tissues mainly through their paracrine actions. One of the important paracrine components of MSC secretomes is the extracellular vesicle (EV). The therapeutic potential of MSC-EVs has been established in various cardiac injury preclinical models. However, the large-scale production of EVs remains a challenge. We sought to develop a scale-up friendly method to generate a large number of therapeutic nanovesicles from MSCs by extrusion. Those extruded nanovesicles (NVs) are miniature versions of MSCs in terms of surface marker expression. The yield of NVs is 20-fold more than that of EVs. In vitro, cell-based assays demonstrated the myocardial protective effects and therapeutic potential of NVs. Intramyocardial delivery of NVs in the injured heart after ischemia-reperfusion led to a reduction in scar sizes and preservation of cardiac functions. Such therapeutic benefits are similar to those injected with natural EVs from the same MSC parental cells. In addition, NV therapy promoted angiogenesis and proliferation of cardiomyocytes in the post-injury heart. In summary, extrusion is a highly efficient method to generate a large quantity of therapeutic NVs that can potentially replace extracellular vesicles in regenerative medicine applications.

Exosomes: Potential Disease Biomarkers and New Therapeutic Targets

Exosomes are extracellular vesicles released by cells, both constitutively and after cell activation, and are present in different types of biological fluid. Exosomes are involved in the pathogenesis of diseases, such as cancer, neurodegenerative diseases, pregnancy disorders and cardiovascular diseases, and have emerged as potential non-invasive biomarkers for the detection, prognosis and therapeutics of a myriad of diseases. In this review, we describe recent advances related to the regulatory mechanisms of exosome biogenesis, release and molecular composition, as well as their role in health and disease, and their potential use as disease biomarkers and therapeutic targets. In addition, the advantages and disadvantages of their main isolation methods, characterization and cargo analysis, as well as the experimental methods used for exosome-mediated drug delivery, are discussed. Finally, we present potential perspectives for the use of exosomes in future clinical practice.