Mitochondria-containing extracellular vesicles (EV) reduce mouse brain infarct sizes and EV/HSP27 protect ischemic brain endothelial cultures

Current targeting strategies and advanced nanoplatforms for atherosclerosis therapy

Atherosclerosis is one of the major causes of death worldwide, and it is closely related to many cardiovascular diseases, such as stroke, myocardial infraction and angina. Although traditional surgical and pharmacological interventions can effectively retard or slow down the progression of atherosclerosis, it is very difficult to prevent or even reverse this disease. In recent years, with the rapid development of nanotechnology, various nanoagents have been designed and applied to different diseases including atherosclerosis. The unique atherosclerotic microenvironment with signature biological components allows nanoplatforms to distinguish atherosclerotic lesions from normal tissue and to approach plaques specifically. Based on the process of atherosclerotic plaque formation, this review summarises the nanodrug delivery strategies for atherosclerotic therapy, trying to provide help for researchers to understand the existing atherosclerosis management approaches as well as challenges and to reasonably design anti-atherosclerotic nanoplatforms.

Horizontal mitochondrial transfer as a novel bioenergetic tool for mesenchymal stromal/stem cells: molecular mechanisms and therapeutic potential in a variety of diseases

Intercellular mitochondrial transfer (MT) is a newly discovered form of cell-to-cell signalling involving the active incorporation of healthy mitochondria into stressed/injured recipient cells, contributing to the restoration of bioenergetic profile and cell viability, reduction of inflammatory processes and normalisation of calcium dynamics. Recent evidence has shown that MT can occur through multiple cellular structures and mechanisms: tunneling nanotubes (TNTs), via gap junctions (GJs), mediated by extracellular vesicles (EVs) and other mechanisms (cell fusion, mitochondrial extrusion and migrasome-mediated mitocytosis) and in different contexts, such as under physiological (tissue homeostasis and stemness maintenance) and pathological conditions (hypoxia, inflammation and cancer). As Mesenchimal Stromal/ Stem Cells (MSC)-mediated MT has emerged as a critical regulatory and restorative mechanism for cell and tissue regeneration and damage repair in recent years, its potential in stem cell therapy has received increasing attention. In particular, the potential therapeutic role of MSCs has been reported in several articles, suggesting that MSCs can enhance tissue repair after injury via MT and membrane vesicle release. For these reasons, in this review, we will discuss the different mechanisms of MSCs-mediated MT and therapeutic effects on different diseases such as neuronal, ischaemic, vascular and pulmonary diseases. Therefore, understanding the molecular and cellular mechanisms of MT and demonstrating its efficacy could be an important milestone that lays the foundation for future clinical trials.

Focusing on mitochondria in the brain: from biology to therapeutics

Mitochondria have multiple functions such as supplying energy, regulating the redox status, and producing proteins encoded by an independent genome. They are closely related to the physiology and pathology of many organs and tissues, among which the brain is particularly prominent. The brain demands 20% of the resting metabolic rate and holds highly active mitochondrial activities. Considerable research shows that mitochondria are closely related to brain function, while mitochondrial defects induce or exacerbate pathology in the brain. In this review, we provide comprehensive research advances of mitochondrial biology involved in brain functions, as well as the mitochondria-dependent cellular events in brain physiology and pathology. Furthermore, various perspectives are explored to better identify the mitochondrial roles in neurological diseases and the neurophenotypes of mitochondrial diseases. Finally, mitochondrial therapies are discussed. Mitochondrial-targeting therapeutics are showing great potentials in the treatment of brain diseases.

Micro Trojan horses: Engineering extracellular vesicles crossing biological barriers for drug delivery

The biological barriers of the body, such as the blood-brain, placental, intestinal, skin, and air-blood, protect against invading viruses and bacteria while providing necessary physical support. However, these barriers also hinder the delivery of drugs to target tissues, reducing their therapeutic efficacy. Extracellular vesicles (EVs), nanostructures with a diameter ranging from 30 nm to 10 μm secreted by cells, offer a potential solution to this challenge. These natural vesicles can effectively pass through various biological barriers, facilitating intercellular communication. As a result, artificially engineered EVs that mimic or are superior to the natural ones have emerged as a promising drug delivery vehicle, capable of delivering drugs to almost any body part to treat various diseases. This review first provides an overview of the formation and cross-species uptake of natural EVs from different organisms, including animals, plants, and bacteria. Later, it explores the current clinical applications, perspectives, and challenges associated with using engineered EVs as a drug delivery platform. Finally, it aims to inspire further research to help bioengineered EVs effectively cross biological barriers to treat diseases.

Exosomes: potential targets for the diagnosis and treatment of neuropsychiatric disorders

The field of neuropsychiatry is considered a middle ground between neurological and psychiatric disorders, thereby bridging the conventional boundaries between matter and mind, consciousness, and function. Neuropsychiatry aims to evaluate and treat cognitive, behavioral, and emotional disorders in individuals with neurological conditions. However, the pathophysiology of these disorders is not yet fully understood, and objective biological indicators for these conditions are currently lacking. Treatment options are also limited due to the blood-brain barrier, which results in poor treatment effects. Additionally, many drugs, particularly antipsychotic drugs, have adverse reactions, which make them difficult to tolerate for patients. As a result, patients often abandon treatment owing to these adverse reactions. Since the discovery of exosomes in 1983, they have been extensively studied in various diseases owing to their potential as nanocellulators for information exchange between cells. Because exosomes can freely travel between the center and periphery, brain-derived exosomes can reflect the state of the brain, which has considerable advantages in diagnosis and treatment. In addition, administration of engineered exosomes can improve therapeutic efficacy, allow lesion targeting, ensure drug stability, and prevent systemic adverse effects. Therefore, this article reviews the source and biological function of exosomes, relationship between exosomes and the blood-brain barrier, relationship between exosomes and the pathological mechanism of neuropsychiatric disorders, exosomes in the diagnosis and treatment of neuropsychiatric disorders, and application of engineered exosomes in neuropsychiatric disorders.

Mitochondria-containing extracellular vesicles from mouse vs . human brain endothelial cells for ischemic stroke therapy

Ischemic stroke-induced mitochondrial dysfunction in the blood-brain barrier-forming brain endothelial cells ( BECs ) results in long-term neurological dysfunction post-stroke. We previously reported that intravenous administration of human BEC ( hBEC )-derived mitochondria-containing extracellular vesicles ( EVs ) showed a potential efficacy signal in a mouse middle cerebral artery occlusion ( MCAo ) model of stroke. We hypothesized that EVs harvested from donor species homologous to the recipient species ( e.g., mouse) may improve therapeutic efficacy, and therefore, use of mouse BEC ( mBEC )-derived EVs may improve post-stroke outcomes in MCAo mice. We investigated if EVs derived from the same species as the recipient cell (mBEC-EVs and recipient mBECs or hBECs-EVs and recipient hBECs) show a greater EV mitochondria delivery efficiency than cross-species EVs and recipient cells (mBEC-EVs and recipient hBECs or vice versa ). Our results showed that mBEC-EVs outperformed hBEC-EVs in transferring EV mitochondria to the recipient ischemic mBECs, and improved mBEC mitochondrial function via increasing oxygen consumption rate. mBEC-EVs significantly reduced brain infarct volume and improved behavioral recovery compared to vehicle-injected MCAo mice. Our data suggests that mBEC-EVs show superior therapeutic efficacy in a mouse MCAo stroke model compared to hBEC-EVs-supporting the continued use of mBEC-EVs to optimize the therapeutic potential of mitochondria-containing EVs in preclinical studies.

Versatile extracellular vesicle-mediated information transfer: intercellular synchronization of differentiation and of cellular phenotypes, and future perspectives

In recent years, extracellular vesicles (EVs) have attracted significant attention as carriers in intercellular communication. The vast array of information contained within EVs is critical for various cellular activities, such as proliferation and differentiation of multiple cell types. Moreover, EVs are being employed in disease diagnostics, implicated in disease etiology, and have shown promise in tissue repair. Recently, a phenomenon has been discovered in which cellular phenotypes, including the progression of differentiation, are synchronized among cells via EVs. This synchronization could be prevalent in widespread different situations in embryogenesis and tissue organization and maintenance. Given the increasing research on multi-cellular tissues and organoids, the role of EV-mediated intercellular communication has become increasingly crucial. This review begins with fundamental knowledge of EVs and then discusses recent findings, various modes of information transfer via EVs, and synchronization of cellular phenotypes.

Targeted delivery of hybrid nanovesicles for enhanced brain penetration to achieve synergistic therapy of glioma

Blood-brain barrier (BBB) obstructing brain drug delivery severely hampers the therapeutic efficacy towards glioma. An efficient brain delivery strategy is of paramount importance for the treatment of glioma. Inspired by brain targeting exosome, biomimetic BBB penetrated hybrid (pHybrid) nanovesicles, engineered by membrane fusion between blood exosome and tLyp-1 peptide modified liposome, is explored for brain targeting drug delivery. Transferrin receptor (TfR) on pHybrid nanovesicles facilitates the BBB transcytosis into brain parenchyma, and eventually endocytosed by glioma cells and diffusion to extra-vascular tumor tissues under the guidance of tLyp-1 peptide. pHybrid nanovesicles co-loaded with salvianolic acid B (SAB) and cryptotanshinone (CPT), which is constructed by membrane hybridization of blood exosome loaded with SAB and tLyp-1 modified liposome loaded with CPT, are explored for cytotoxic and anti-angiogenetic therapy towards glioma. Upon accumulation at tumor site, the loaded CPT and SAB shows synergistic effects towards glioma from cytotoxicity on cancer cells and anti-angiogenesis on tumor, respectively. Overall, this study provides a biomimetic nanoplatform for increased BBB transcytosis into brain parenchyma, which serves as a prospective strategy for delivering therapeutic agents against glioma through synergistic mechanisms.

Mitochondrial-targeted and ROS-responsive nanocarrier via nose-to-brain pathway for ischemic stroke treatment

Oxidative stress injury and mitochondrial dysfunction are major obstacles to neurological functional recovery after ischemic stroke. The development of new approaches to simultaneously diminish oxidative stress and resist mitochondrial dysfunction is urgently needed. Inspired by the overproduced reactive oxygen species (ROS) at ischemic neuron mitochondria, multifunctional nanoparticles with ROS-responsiveness and mitochondrial-targeted (SPNPs) were engineered, achieving specific targeting delivery and controllable drug release at ischemic penumbra. Due to the nose-to-brain pathway, SPNPs which were encapsulated in a thermo-sensitive gel by intranasal administration were directly delivered to the ischemic penumbra bypassing the blood‒brain barrier (BBB) and enhancing delivery efficiency. The potential of SPNPs for ischemic stroke treatment was systematically evaluated in vitro and in rat models of middle cerebral artery occlusion (MCAO). Results demonstrated the mitochondrial-targeted and protective effects of SPNPs on H2O2-induced oxidative damage in SH-SY5Y cells. In vivo distribution analyzed by fluorescence imaging proved the rapid and enhanced active targeting of SPNPs to the ischemic area in MCAO rats. SPNPs by intranasal administration exhibited superior therapeutic efficacy by alleviating oxidative stress, diminishing inflammation, repairing mitochondrial function, and decreasing apoptosis. This strategy provided a multifunctional delivery system for the effective treatment of ischemic injury, which also implies a potential application prospect for other central nervous diseases.

Mitochondrial transfer between cell crosstalk - An emerging role in mitochondrial quality control

Intercellular signaling and component conduction are essential for multicellular organisms' homeostasis, and mitochondrial transcellular transport is a key example of such cellular component exchange. In physiological situations, mitochondrial transfer is linked with biological development, energy coordination, and clearance of harmful components, remarkably playing important roles in maintaining mitochondrial quality. Mitochondria are engaged in many critical biological activities, like oxidative metabolism and biomolecular synthesis, and are exclusively prone to malfunction in pathological processes. Importantly, severe mitochondrial damage will further amplify the defects in the mitochondrial quality control system, which will mobilize more active mitochondrial transfer, replenish exogenous healthy mitochondria, and remove endogenous damaged mitochondria to facilitate disease outcomes. This review explores intercellular mitochondrial transport in cells, its role in cellular mitochondrial quality control, and the linking mechanisms in cellular crosstalk. We also describe advances in therapeutic strategies for diseases that target mitochondrial transfer.

Bio-clickable, small extracellular vesicles-COCKTAIL therapy for ischemic stroke

Delivering large therapeutic molecules via the blood-brain barrier to treat ischemic stroke remains challenging. NR2B9c is a potent neuroprotective peptide but it's safe and targeted delivery to the brain requires an efficient, natural, and non-immunogenic delivery technique. Small extracellular vesicles (sEVs) have shown great potential as a non-immunogenic, natural cargo delivery system; however, tailoring of its inefficient brain targeting is desired. Here, we coupled rabies virus glycoprotein 29 with sEVs surface via bio-orthogonal click chemistry reactions, followed by loading of NR2B9c, ultimately generating stroke-specific therapeutic COCKTAIL (sEVs-COCKTAIL). Primary neurons and Neuro-2a cells were cultured for in vitro and transient middle cerebral artery occlusion model was used for in vivo studies to evaluate neuron targeting and anti-ischemic stroke potential of the sEVs-COCKTAIL. Bio-clickable sEVs were selectively taken up by neurons but not glial cells. In the in vitro ischemic stroke model of oxygen-glucose deprivation, the sEVs-COCKTAIL exhibited remarkable potential against reactive oxygen species and cellular apoptosis. In vivo studies further demonstrated the brain targeting and increased half-life of bio-clickable sEVs, delivering NR2B9c to the ischemic brain and reducing stroke injury. Treatment with the sEVs-COCKTAIL significantly increased behavioral recovery and reduced neuronal apoptosis after transient middle cerebral artery occlusion. NR2B9c was delivered to neurons binding to post-synaptic density protein-95, inhibiting N-methyl-d-Aspartate receptor-mediated over production of oxidative stress and mitigating protein B-cell lymphoma 2 and P38 proteins expression. Our results provide an efficient and biocompatible approach to a targeted delivery system, which is a promising modality for stroke therapy.

Engineered Extracellular Vesicles: Emerging Therapeutic Strategies for Translational Applications

Extracellular vesicles (EVs) are small, membrane-bound vesicles used by cells to deliver biological cargo such as proteins, mRNA, and other biomolecules from one cell to another, thus inducing a specific response in the target cell and are a powerful method of cell to cell and organ to organ communication, especially during the pathogenesis of human disease. Thus, EVs may be utilized as prognostic and diagnostic biomarkers, but they also hold therapeutic potential just as mesenchymal stem cells have been used in therapeutics. However, unmodified EVs exhibit poor targeting efficacy, leading to the necessity of engineered EVS. To highlight the advantages and therapeutic promises of engineered EVs, in this review, we summarized the research progress on engineered EVs in the past ten years, especially in the past five years, and highlighted their potential applications in therapeutic development for human diseases. Compared to the existing stem cell-derived EV-based therapeutic strategies, engineered EVs show greater promise in clinical applications: First, engineered EVs mediate good targeting efficacy by exhibiting a targeting peptide that allows them to specifically target a specific organ or even cell type, thus avoiding accumulation in undesired locations and increasing the potency of the treatment. Second, engineered EVs can be artificially pre-loaded with any necessary biomolecular cargo or even therapeutic drugs to treat a variety of human diseases such as cancers, neurological diseases, and cardiovascular ailments. Further research is necessary to improve logistical challenges in large-scale engineered EV manufacturing, but current developments in engineered EVs prove promising to greatly improve therapeutic treatment for traditionally difficult to treat diseases.

Delivery of mitochondria-containing extracellular vesicles to the BBB for ischemic stroke therapy

INTRODUCTION

Ischemic stroke-induced mitochondrial dysfunction in brain endothelial cells (BECs) leads to breakdown of the blood-brain barrier (BBB) causing long-term neurological dysfunction. Restoration of mitochondrial function in injured BECs is a promising therapeutic strategy to alleviate stroke-induced damage. Mounting evidence demonstrate that selected subsets of cell-derived extracellular vehicles (EVs), such as exosomes (EXOs) and microvesicles (MVs), contain functional mitochondrial components. Therefore, development of BEC-derived mitochondria-containing EVs for delivery to the BBB will (1) alleviate mitochondrial dysfunction and limit long-term neurological dysfunction in ischemic stroke and (2) provide an alternative therapeutic option for treating numerous other diseases associated with mitochondrial dysfunction.

AREA COVERED

This review will discuss (1) how EV subsets package different types of mitochondrial components during their biogenesis, (2) mechanisms of EV internalization and functional mitochondrial responses in the recipient cells, and (3) EV biodistribution and pharmacokinetics - key factors involved in the development of mitochondria-containing EVs as a novel BBB-targeted stroke therapy.

EXPERT OPINION

Mitochondria-containing MVs have demonstrated therapeutic benefits in ischemic stroke and other pathologies associated with mitochondrial dysfunction. Delivery of MV mitochondria to the BBB is expected to protect the BBB integrity and neurovascular unit post-stroke. MV mitochondria quality control, characterization, mechanistic understanding of its effects in vivo, safety and efficacy in different preclinical models, large-scale production, and establishment of regulatory guidelines are foreseeable milestones to harness the clinical potential of MV mitochondria delivery.