Effects of Mesenchymal Stem Cell-Derived Exosomes on Experimental Autoimmune Uveitis

Topical ophthalmic instillation of engineered hMSCs-derived exosomes: A novel non-invasive therapeutic strategy for ocular posterior-segment disorder

Due to the presence of protective mechanisms and blood-ocular barriers in the eye, drugs aimed at treating posterior segment ophthalmic disorder have to be administrated mostly through periocular or intravitreal injection. In the current study, we sought to investigate whether topical ophthalmic instillation of human mesenchymal stem cells (hMSCs)-derived exosomes can prevent and treat experimental autoimmune uveitis (EAU), a posterior segment ophthalmic disease induced in animals and considered a model of human autoimmune diseases of the eye. Our studies reveal that topical ophthalmic instillation of hMSCs-derived exosomes can effectively ameliorate EAU. More importantly, we demonstrate that exosomes modified by trans-activator of transcription peptide (TAT) were more effective than naive exosomes in penetrating ocular barrier and preventing/treating EAU. Taken together, these results indicate that topical ophthalmic instillation of TAT-peptide modified exosomes represents a novel non-invasive therapeutic strategy for posterior-segment ophthalmic disorders.

The role of adiponectin and its receptor signaling in ocular inflammation-associated diseases

Ocular inflammation-associated diseases are leading causes of global visual impairment, with limited treatment options. Adiponectin, a hormone primarily secreted by adipose tissue, binds to its receptors, which are widely distributed throughout the body, exerting powerful physiological regulatory effects. The protective role of adiponectin in various inflammatory diseases has gained increasing attention in recent years. Previous studies have confirmed the presence of adiponectin and its receptors in the eyes. Furthermore, adiponectin and its analogs have shown potential as novel drugs for the treatment of inflammatory eye diseases. This article summarizes the evidence for the interplay between adiponectin and inflammatory eye diseases and provides new perspectives on the diagnostic and therapeutic possibilities of adiponectin.

Small extracellular vesicles derived from microRNA-22-3p-overexpressing mesenchymal stem cells protect retinal ganglion cells by regulating MAPK pathway

Glaucoma is the leading cause of irreversible blindness and is characterized by progressive retinal ganglion cell (RGC) loss and retinal nerve fiber layer thinning. Currently, no existing treatment is effective for the preservation of RGCs. MicroRNA-22-3p (miR22) and small extracellular vesicles derived from mesenchymal stem cells (MSC-sEVs) have neuroprotective effects. In this study, we apply miR22-overexpressing MSC-sEVs in an N-methyl-D-aspartic acid (NMDA)-induced RGC injury model to assess their short-term therapeutic effects and explore the underlying mechanisms. We find that mice in the miR22-sEVs-treated group have thicker retinas, fewer apoptotic cells, more reserved RGCs, better retinal function, and lower expression levels of Bax and caspase-3. MiR22-sEVs treatment promotes viability, inhibits apoptosis and inhibits Bax and caspase-3 expression in RGC-5 cells. MiR22 targets mitogen-activated protein kinase kinase kinase 12 to inhibit apoptosis by regulating the mitogen-activated protein kinase (MAPK) signaling pathway. Collectively, our results suggest that miR22-sEVs ameliorate NMDA-induced RGC injury through the inhibition of MAPK signaling pathway-mediated apoptosis, providing a potential therapy for glaucoma and other diseases that involve RGC damage.

Mesenchymal stem cell based therapies for uveitis: a systematic review of preclinical studies

Cell therapy has shown promising results for treating uveitis in preclinical studies. As the field continues to grow towards clinical translation, it is important to review and critically appraise existing studies. Herein, we analysed and critically appraised all preclinical studies using cell therapy or cell derived extracellular vesicles (EVs) for uveitis, and provided insight into mechanisms regulating ocular inflammation. We used PubMed, Medline, and Embase to search for preclinical studies examining stem cell therapy (e.g., mesenchymal stem cells [MSC]) and secreted EVs. All included studies were assessed for quality using the SYstematic Review Center for Laboratory animal Experimentation (SYRCLE) checklist. Sixteen preclinical studies from 2011 to 2022 were analysed and included in this review of which 75% (n = 12) focused only on cell therapy, 18.7% (n = 3) studies focused on EVs, and 6.3% (n = 1) study focused on both cells and EVs. MSCs were the most common type of cells used in preclinical studies (n = 15) and EVs were commonly isolated from MSCs (n = 3). Overall, both MSCs and EVs showed improvements in ocular inflammation (seen on fundoscopy/slit lamp and histology) and electroretinogram outcomes. Overall, MSC and MSC-derived EVs shown great potential as therapeutic agents for treating uveitis. Unfortunately, small sample size, risk of selection/performance bias, and lack of standardized cell harvesting or delivery protocols are some factors which limits clinical translation. Large scaled, randomized preclinical studies are required to understand the full potential of MSCs for treating uveitis.

Small extracellular vesicle-based delivery of interleukin-10 improves treatment of experimental autoimmune uveitis

Non-infectious uveitis is an intraocular autoimmune disease mainly characterized by immune dysregulation of the eye, which may cause blindness if not well treated. Interleukin 10 (IL-10) is a potent cytokine with multiple immunoregulatory functions. However, it's in vivo activity is unstable owing to its inherent protein instability and short plasma half-life. Therefore, our previous research tried to establish IL-10-overexpressing MSC-sEVs (sEVs-IL10) using lentiviral transfection. While this approach indeed improved drug delivery, it also suffered from tedious procedures and limited loading efficiency. Accordingly, we constructed a novel MSC-sEVs-based delivery system for IL-10 (IL-10@sEVs) by sonication. The obtained formulation (IL-10@sEVs) had relatively higher loading efficiency and exerted a more profound immunomodulatory effect than sEVs-IL10 in vitro. Furthermore, IL-10@sEVs had significant therapeutic effects in a mouse model of experimental autoimmune uveitis (EAU) by decreasing the percentage of Th17 cells, increasing regulatory T cells in the eye, and draining lymph nodes. In summary, sonication outperforms conventional transfection methods for loading IL-10 into MSC-sEVs.

Neuroprotective effect of human cord blood-derived extracellular vesicles by improved neuromuscular function and reduced gliosis in a rat model of Huntington's disease

Huntington's disease (HD) is a hereditary condition characterized by the gradual deterioration of nerve cells in the striatum. Recent scientific investigations have revealed the promising potential of Extracellular vesicles (EVs) as a therapy to mitigate inflammation and enhance motor function. This study aimed to examine the impact of administering EVs derived from human umbilical cord blood (HUCB) on the motor abilities and inflammation levels in a rat model of HD. After ultracentrifugation to prepare EVs from HUCB to determine the nature of the obtained contents, the expression of CD markers 81 and 9, the average size and also the morphology of its particles were investigated by DLS and Transmission electron microscopy (TEM). Then, in order to induce the HD model, 3-nitropropionic acid (3-NP) neurotoxin was injected intraperitoneal into the rats, after treatment by HUCB-EVs, rotarod, electromyogram (EMG) and the open field tests were performed on the rats. Finally, after rat sacrifice and the striatum was removed, Hematoxylin and eosin staining (H&E), stereology, immunohistochemistry, antioxidant tests, and western blot were performed. Our results showed that the contents of the HUCB-EVs express the CD9 and CD81 markers and have spherical shapes. In addition, the injection of HUCB-EVs improved motor and neuromuscular function, reduced gliosis, increased antioxidant activity and inflammatory factor, and partially prevented the decrease of neurons. The findings generally show that HUCB-EVs have neuroprotective effects and reduce neuroinflammation from the toxic effects of 3-NP, which can be beneficial for the recovery of HD.

Immunomodulatory effects of extracellular vesicles from mesenchymal stromal cells: Implication for therapeutic approach in autoimmune diseases

Autoimmune disease is characterized by the proliferation of harmful immune cells, inducing tissue inflammation and ultimately causing organ damage. Current treatments often lack specificity, necessitating high doses, prolonged usage, and high recurrence rates. Therefore, the identification of innovative and safe therapeutic strategies is urgently required. Recent preclinical studies and clinical trials on inflammatory and autoimmune diseases have evidenced the immunosuppressive properties of mesenchymal stromal cells (MSCs). Studies have demonstrated that extracellular vesicles (EV) derived from MSCs can mitigate abnormal autoinflammation while maintaining safety within the diseased microenvironment. This study conducted a systematic review to elucidate the crucial role of MSC-EVs in alleviating autoimmune diseases, particularly focusing on their impact on the underlying mechanisms of autoimmune conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD). By specifically examining the regulatory functions of microRNAs (miRNAs) derived from MSC-EVs, the comprehensive study aimed to enhance the understanding related to disease mechanisms and identify potential diagnostic markers and therapeutic targets for these diseases.

Potential in exosome-based targeted nano-drugs and delivery vehicles for posterior ocular disease treatment: from barriers to therapeutic application

Posterior ocular disease, a disease that accounts for 55% of all ocular diseases, can contribute to permanent vision loss if left without treatment. Due to the special structure of the eye, various obstacles make it difficult for drugs to reach lesions in the posterior ocular segment. Therefore, the development of highly permeable targeted drugs and delivery systems is particularly important. Exosomes are a class of extracellular vesicles at 30-150 nm, which are secreted by various cells, tissues, and body fluids. They carry various signaling molecules, thus endowing them with certain physiological functions. In this review, we describe the ocular barriers and the biogenesis, isolation, and engineering of exosomes, as exosomes not only have pharmacological effects but also are good nanocarriers with targeted properties. Moreover, their biocompatibility and immunogenicity are better than synthetic nanocarriers. Most importantly, they may have the ability to pass through the blood-eye barrier. Thus, they may be developed as both targeted nano-drugs and nano-delivery vehicles for the treatment of posterior ocular diseases. We focus on the current status and potential application of exosomes as targeted nano-drugs and nano-delivery vehicles in posterior ocular diseases.

CCR5-overexpressing mesenchymal stem cells protect against experimental autoimmune uveitis: insights from single-cell transcriptome analysis

Autoimmune uveitis is a leading cause of severe vision loss, and animal models provide unique opportunities for studying its pathogenesis and therapeutic strategies. Here we employ scRNA-seq, RNA-seq and various molecular and cellular approaches to characterize mouse models of classical experimental autoimmune uveitis (EAU), revealing that EAU causes broad retinal neuron degeneration and marker downregulation, and that Müller glia may act as antigen-presenting cells. Moreover, EAU immune response is primarily driven by Th1 cells, and results in dramatic upregulation of CC chemokines, especially CCL5, in the EAU retina. Accordingly, overexpression of CCR5, a CCL5 receptor, in mesenchymal stem cells (MSCs) enhances their homing capacity and improves their immunomodulatory outcomes in preventing EAU, by reducing infiltrating T cells and activated microglia and suppressing Nlrp3 inflammasome activation. Taken together, our data not only provide valuable insights into the molecular characteristics of EAU but also open an avenue for innovative MSC-based therapy.

Enhanced immunosuppressive capability of mesenchymal stem cell-derived small extracellular vesicles with high expression of CD73 in experimental autoimmune uveitis

BACKGROUND

Autoimmune uveitis is an inflammatory disease triggered by an aberrant immune response. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) are emerging as potential therapeutic agents for this condition. CD73, an ectoenzyme present on MSC-sEVs, is involved in mitigating inflammation by converting extracellular adenosine monophosphate into adenosine. We hypothesize that the inhibitory effect of MSC-sEVs on experimental autoimmune uveitis (EAU) could be partially attributed to the surface expression of CD73.

METHODS

To investigate novel therapeutic approaches for autoimmune uveitis, we performed lentiviral transduction to overexpress CD73 on the surface of MSC-sEVs, yielding CD73-enriched MSC-sEVs (sEVs-CD73). Mice with interphotoreceptor retinoid-binding protein (IRBP)-induced EAU were grouped randomly and treated with 50 µg MSC-sEVs, vector infected MSC-sEVs, sEVs-CD73 or PBS via single tail vein injection. We evaluated the clinical and histological features of the induced mice and analyzed the proportion and functional capabilities of T helper cells. Furthermore, T-cells were co-cultured with various MSC-sEVs in vitro, and we quantified the resulting inflammatory response to assess the potential therapeutic benefits of sEVs-CD73.

RESULTS

Compared to MSC-sEVs, sEVs-CD73 significantly alleviates EAU, leading to reduced inflammation and diminished tissue damage. Treatment with sEVs-CD73 results in a decreased proportion of Th1 cells in the spleen, draining lymph nodes, and eyes, accompanied by an increased proportion of regulatory T-cells (Treg cells). In vitro assays further reveal that sEVs-CD73 inhibits T-cell proliferation, suppresses Th1 cells differentiation, and enhances Treg cells proportion.

CONCLUSION

Over-expression of CD73 on MSC-sEVs enhances their immunosuppressive effects in EAU, indicating that sEVs-CD73 has the potential as an efficient immunotherapeutic agent for autoimmune uveitis.

New advances in immune mechanism and treatment during ocular toxoplasmosis

Ocular toxoplasmosis (OT) is an intraocular infection caused by the parasite Toxoplasma gondii. OT is manifested as retinal choroiditis and is the most common infectious cause of posterior uveitis. Invasion of the retina by T. gondii leads to disruption of the blood-ocular barrier and promotes the migration of immune cells to the ocular tissues. Cytokines such as IFN-γ and IL-1β are effective for controlling parasite growth, but excessive inflammatory responses can cause damage to the host. In this review, we will discuss in detail the latest advances in the immunopathology and treatment of OT.

miRNA-148a-containing GMSC-derived EVs modulate Treg/Th17 balance via IKKB/NF-κB pathway and treat a rheumatoid arthritis model

Mesenchymal stem cells (MSCs) have demonstrated potent immunomodulatory properties that have shown promise in the treatment of autoimmune diseases, including rheumatoid arthritis (RA). However, the inherent heterogeneity of MSCs triggered conflicting therapeutic outcomes, raising safety concerns and limiting their clinical application. This study aimed to investigate the potential of extracellular vesicles derived from human gingival mesenchymal stem cells (GMSC-EVs) as a therapeutic strategy for RA. Through in vivo experiments using an experimental RA model, our results demonstrate that GMSC-EVs selectively homed to inflamed joints and recovered Treg and Th17 cell balance, resulting in the reduction of arthritis progression. Our investigations also uncovered miR-148a-3p as a critical contributor to the Treg/Th17 balance modulation via IKKB/NF-κB signaling orchestrated by GMSC-EVs, which was subsequently validated in a model of human xenograft versus host disease (xGvHD). Furthermore, we successfully developed a humanized animal model by utilizing synovial fibroblasts obtained from patients with RA (RASFs). We found that GMSC-EVs impeded the invasiveness of RASFs and minimized cartilage destruction, indicating their potential therapeutic efficacy in the context of patients with RA. Overall, the unique characteristics - including reduced immunogenicity, simplified administration, and inherent ability to target inflamed tissues - position GMSC-EVs as a viable alternative for RA and other autoimmune diseases.

Rescuing Photoreceptors in RPE Dysfunction-Driven Retinal Degeneration: The Role of Small Extracellular Vesicles Secreted from Retinal Pigment Epithelium

Dysfunction of the retinal pigment epithelium (RPE) is a common shared pathology in major degenerative retinal diseases despite variations in the primary etiologies of each disease. Due to their demanding and indispensable functional roles throughout the lifetime, RPE cells are vulnerable to genetic predisposition, external stress, and aging processes. Building upon recent advancements in stem cell technology for differentiating healthy RPE cells and recognizing the significant roles of small extracellular vesicles (sEV) in cellular paracrine and autocrine actions, we investigated the hypothesis that the RPE-secreted sEV alone can restore essential RPE functions and rescue photoreceptors in RPE dysfunction-driven retinal degeneration. Our findings support the rationale for developing intravitreal treatment of sEV. We demonstrate that intravitreally delivered sEV effectively penetrate the full thickness of the retina. Xenogenic intraocular administration of human-derived EVs did not induce acute immune reactions in rodents. sEV derived from human embryonic stem cell (hESC)-derived fully differentiated RPE cells, but not sEV-depleted conditioned cell culture media (CCM minus sEV), rescued photoreceptors and their function in a Royal College of Surgeons (RCS) rat model. This model is characterized by photoreceptor death and retinal degeneration resulting from a mutation in the MerTK gene in RPE cells. From the bulk RNA sequencing study, we identified 447 differently expressed genes in the retina after hESC-RPE-sEV treatment compared with the untreated control. Furthermore, 394 out of 447 genes (88%) showed a reversal in expression toward the healthy state in Long-Evans (LE) rats after treatment compared to the diseased state. Particularly, detrimental alterations in gene expression in RCS rats, including essential RPE functions such as phototransduction, vitamin A metabolism, and lipid metabolism were partially reversed. Defective photoreceptor outer segment engulfment due to intrinsic MerTK mutation was partially ameliorated. These findings suggest that RPE-secreted sEV may play a functional role similar to that of RPE cells. Our study justifies further exploration to fully unlock future therapeutic interventions with sEV in a broad array of degenerative retinal diseases.

Regenerative Therapy for Corneal Scarring Disorders

The cornea is a transparent and vitally multifaceted component of the eye, playing a pivotal role in vision and ocular health. It has primary refractive and protective functions. Typical corneal dysfunctions include opacities and deformities that result from injuries, infections, or other medical conditions. These can significantly impair vision. The conventional challenges in managing corneal ailments include the limited regenerative capacity (except corneal epithelium), immune response after donor tissue transplantation, a risk of long-term graft rejection, and the global shortage of transplantable donor materials. This review delves into the intricate composition of the cornea, the landscape of corneal regeneration, and the multifaceted repercussions of scar-related pathologies. It will elucidate the etiology and types of dysfunctions, assess current treatments and their limitations, and explore the potential of regenerative therapy that has emerged in both in vivo and clinical trials. This review will shed light on existing gaps in corneal disorder management and discuss the feasibility and challenges of advancing regenerative therapies for corneal stromal scarring.

Exosomal noncoding RNA: A potential therapy for retinal vascular diseases

Exosomes are extracellular vesicles that can contain DNA, RNA, proteins, and metabolites. They are secreted by cells and play a regulatory role in various biological responses by mediating cell-to-cell communication. Moreover, exosomes are of interest in developing therapies for retinal vascular disorders because they can deliver various substances to cellular targets. According to recent research, exosomes can be used as a strategy for managing retinal vascular diseases, and they are being investigated for therapeutic purposes in eye conditions, including glaucoma, dry eye syndrome, retinal ischemia, diabetic retinopathy, and age-related macular degeneration. However, the role of exosomal noncoding RNA in retinal vascular diseases is not fully understood. Here, we reviewed the latest research on the biological role of exosomal noncoding RNA in treating retinal vascular diseases. Research has shown that noncoding RNAs, including microRNAs, circular RNAs, and long noncoding RNAs play a significant role in the regulation of retinal vascular diseases. Furthermore, through exosome engineering, the expression of relevant noncoding RNAs in exosomes can be controlled to regulate retinal vascular diseases. Therefore, this review suggests that exosomal noncoding RNA could be considered as a biomarker for diagnosis and as a therapeutic target for treating retinal vascular disease.

Isolation and Characterization of Extracellular Vesicles Through Orthogonal Approaches for the Development of Intraocular EV Therapy

Purpose

Isolating extracellular vesicles (EVs) with high yield, replicable purity, and characterization remains a bottleneck in the development of EV therapeutics. To address these challenges, the current study aims to establish the necessary framework for preclinical and clinical studies in the development of stem cell-derived intraocular EV therapeutics.

Methods

Small EVs (sEVs) were separated from the conditioned cell culture medium (CCM) of the human embryogenic stem cell-derived fully polarized retinal pigment epithelium (hESC-RPE-sEV) by a commercially available microfluidic tangential flow filtration (TFF) device ExoDisc (ED) or differential ultracentrifugation (dUC). The scaling and concentration capabilities and purity of recovered sEVs were assessed. Size, number, and surface markers of sEVs were determined by orthogonal approaches using multiple devices.

Results

ED yielded higher numbers of sEVs, ranging from three to eight times higher depending on the measurement device, compared to dUC using the same 5 mL of CCM input. Within the same setting, the purity of ED-recovered hESC-RPE-sEVs was higher than that for dUC-recovered sEVs. ED yielded a higher concentration of particles, which is strongly correlated with the input volume, up to 10 mL (r = 0.98, P = 0.016). Meanwhile, comprehensive characterization profiles of EV surface markers between ED- and dUC-recovered hESC-RPE-sEVs were compatible.

Conclusions

Our study supports TFF as a valuable strategy for separating sEVs for the development of intraocular EV therapeutics. However, there is a growing need for diverse devices to optimize TFF for use in EV preparation. Using orthogonal approaches in EV characterization remains ideal for reliably characterizing heterogeneous EV.

Harnessing the therapeutic potential of mesenchymal stem/stromal cell-derived extracellular vesicles as a novel cell-free therapy for animal models of multiple sclerosis

Multiple sclerosis (MS) is a chronic, neuroinflammatory, and demyelinating disease of the central nervous system (CNS). Current treatments offer only limited relief from symptoms, and there is no cure. Mesenchymal stem/stromal cells (MSCs) have demonstrated therapeutic potential for MS. However, their clinical application faces challenges, including immune rejection and the potential for tumor formation. Recent studies suggest that MSCs exert their effects through extracellular vesicles (EVs) released from the cells, rather than direct cellular engraftment or differentiation. This discovery has sparked interest in the potential of MSC-derived EVs as a cell-free therapy for MS. This review explores the existing literature on the effects of MSC-EVs in animal models of MS. Administration of MSC-EVs from various tissue sources, such as bone marrow, adipose tissue, and umbilical cord, was found to reduce clinical scores and slow down disease progression in experimental autoimmune encephalomyelitis (EAE), the primary mouse model of MS. The mechanisms involved immunomodulation through effects on T cells, cytokines, CNS inflammation, and demyelination. Although the impact on CNS repair markers remained unclear, MSC-EVs exhibited the potential to modulate neuroinflammation and suppress harmful immune responses in EAE. Further studies are still required, but MSC-EVs demonstrate promising therapeutic effects for MS and warrant further exploration as a novel treatment approach.

Smart Nanoscale Extracellular Vesicles in the Brain: Unveiling their Biology, Diagnostic Potential, and Therapeutic Applications

Information exchange is essential for the brain, where it communicates the physiological and pathological signals to the periphery and vice versa. Extracellular vesicles (EVs) are a heterogeneous group of membrane-bound cellular informants actively transferring informative calls to and from the brain via lipids, proteins, and nucleic acid cargos. In recent years, EVs have also been widely used to understand brain function, given their "cell-like" properties. On the one hand, the presence of neuron and astrocyte-derived EVs in biological fluids have been exploited as biomarkers to understand the mechanisms and progression of multiple neurological disorders; on the other, EVs have been used in designing targeted therapies due to their potential to cross the blood-brain-barrier (BBB). Despite the expanding literature on EVs in the context of central nervous system (CNS) physiology and related disorders, a comprehensive compilation of the existing knowledge still needs to be made available. In the current review, we provide a detailed insight into the multifaceted role of brain-derived extracellular vesicles (BDEVs) in the intricate regulation of brain physiology. Our focus extends to the significance of these EVs in a spectrum of disorders, including brain tumors, neurodegenerative conditions, neuropsychiatric diseases, autoimmune disorders, and others. Throughout the review, parallels are drawn for using EVs as biomarkers for various disorders, evaluating their utility in early detection and monitoring. Additionally, we discuss the promising prospects of utilizing EVs in targeted therapy while acknowledging the existing limitations and challenges associated with their applications in clinical scenarios. A foundational comprehension of the current state-of-the-art in EV research is essential for informing the design of future studies.

Extracellular vesicles for developing targeted hearing loss therapy

Substantial efforts have been made for local administration of small molecules or biologics in treating hearing loss diseases caused by either trauma, genetic mutations, or drug ototoxicity. Recently, extracellular vesicles (EVs) naturally secreted from cells have drawn increasing attention on attenuating hearing impairment from both preclinical studies and clinical studies. Highly emerging field utilizing diverse bioengineering technologies for developing EVs as the bioderived therapeutic materials, along with artificial intelligence (AI)-based targeting toolkits, shed the light on the unique properties of EVs specific to inner ear delivery. This review will illuminate such exciting research field from fundamentals of hearing protective functions of EVs to biotechnology advancement and potential clinical translation of functionalized EVs. Specifically, the advancements in assessing targeting ligands using AI algorithms are systematically discussed. The overall translational potential of EVs is reviewed in the context of auditory sensing system for developing next generation gene therapy.

A Bibliometric Analysis of Uveitis in the Past 20 Years

PURPOSE

To assess the quantity and quality of global research on uveitis, visualize the research hotspots, and reveal the study trends in uveitis.

METHODS

This bibliometric analysis was performed with the data obtained from the Web of Science core collection (WoSCC) database and Scopus. Bibliometrix and VOSviewer were used to analyze and visualize study trends and hotspots. Citespace was used to conduct the cooperation and co-citation network analysis.

RESULTS

A total of 5837 and 7195 documents were exported for further analysis in WoSCC and Scopus, respectively. The USA has published the most articles related to uveitis (1627, 27.87%, WoS; 1979, 27.51%, Scopus) and accounted for the most frequency of total citations (42345 times total citations 35 900 times without self-citations in WoSCC database). Most of the papers focusing on uveitis were published in Ocular Immunology and Inflammation (761, 13.04% within WoS; 793, 11.02% within Scopus). Additionally, novel biotherapy is the hotspot of uveitis research which also may be a sustained research interest in the future.

CONCLUSIONS

An increasing trend of publications was found in uveitis research. The USA was the leading contributor in this field, and it was the center of cooperation network. Our study provided an overview of uveitis research, which may serve as a valuable reference and guide for stakeholders interested in uveitis.

Extracellular vesicles and their engineering strategies, delivery systems, and biomedical applications

Extracellular vesicles are nanoscale vesicles that can be secreted by all cell types, are intracellular in origin and have the same composition as their parent cells, play a key role in intercellular communication in organismal health and disease, and are now often used as biomarkers of disease and therapeutic agents in biomedical research. When injected locally or systemically, they have the ability to provide a variety of therapeutic effects, for example, regeneration of skin damage or restoration of cardiac function. However, direct injection of extracellular vesicles may result in their rapid clearance from the injection site.In order to maintain the biological activity of extracellular vesicles and to control the release of effective concentrations for better therapeutic efficacy during long-term disease treatment, the design of an optimized drug delivery system is necessary and different systems for the continuous delivery of extracellular vesicles have been developed. This paper first provides an overview of the biogenesis, composition and physiological function of extracellular vesicles, followed by a review of different strategies for extracellular vesicle isolation and methods for engineering extracellular vesicles. In addition, this paper reviews the latest extracellular vesicle delivery platforms such as micro-nanoparticles, injectable hydrogels, microneedles and scaffold patches. At the same time, the research progress and key cases of extracellular vesicle delivery systems in the field of biomedical therapeutics are described. Finally, the challenges and future trends of extracellular vesicle delivery are discussed.

Mesenchymal stem cell-derived exosomes in preeclampsia: A next-generation therapeutic tool

Preeclampsia (PE) is a major gestational disorder that causes both long- and short-term damage to both the mother and the fetus. Endometrium decidualization and the formation of the placenta are orchestrated by mesenchymal stem cells (MSCs). MSCs obtained from patients with PE exhibit an elevated rate of aging and apoptosis, which impairs the interplay between MSCs and endothelium, trophoblast, and immune cells in the placenta, accelerating the onset of PE. Preclinical and clinical evidence imply that the MSC-based therapy approach for PE is prospective. Importantly, as a novel cell-free approach, MSC-derived exosomes can improve symptoms and maternal-fetal survival in PE models by raising cell metabolism, encouraging angiogenesis balance, and regulating immune responses. Even following allogeneic administration, the likelihood of immune rejection is very limited as a result of the small quantity of exosome membrane-bound proteins. Furthermore, because exosomes do not expand, developing tumors is not probable. As a result, MSC-derived exosomes show superiority over MSCs in terms of safety. For the first time, we outline the properties of MSC-exosomes and highlight their functions and potential as a new paradigm for PE therapy in this review.

Exploring therapeutic avenues: mesenchymal stem/stromal cells and exosomes in confronting enigmatic biofilm-producing fungi

Fungal infections concomitant with biofilms can demonstrate an elevated capacity to withstand substantially higher concentrations of antifungal agents, contrasted with infectious diseases caused by planktonic cells. This inherent resilience intrinsic to biofilm-associated infections engenders a formidable impediment to effective therapeutic interventions. The different mechanisms that are associated with the intrinsic resistance of Candida species encompass drug sequestration by the matrix, drug efflux pumps, stress response cell density, and the presence of persister cells. These persisters, a subset of fungi capable of surviving hostile conditions, pose a remarkable challenge in clinical settings in virtue of their resistance to conventional antifungal therapies. Hence, an exigent imperative has arisen for the development of novel antifungal therapeutics with specific targeting capabilities focused on these pathogenic persisters. On a global scale, fungal persistence and their resistance within biofilms generate an urgent clinical need for investigating recently introduced therapeutic strategies. This review delves into the unique characteristics of Mesenchymal stem/stromal cells (MSCs) and their secreted exosomes, which notably exhibit immunomodulatory and regenerative properties. By comprehensively assessing the current literature and ongoing research in this field, this review sheds light on the plausible mechanisms by which MSCs and their exosomes can be harnessed to selectively target fungal persisters. Additionally, prospective approaches in the use of cell-based therapeutic modalities are examined, emphasizing the importance of further research to overcome the enigmatic fungal persistence.

Effects of inflammation on myopia: evidence and potential mechanisms

As the most common type of refractive error, myopia has become one of the leading causes of visual impairment. With the increasing prevalence of myopia, there is a growing need to better understand the factors involved in its development. Inflammation, one of the most fundamental pathophysiological processes in humans, is a rapid response triggered by harmful stimuli and conditions. Although controlled inflammatory responses are necessary, over-activated inflammation is the common soil for many diseases. The impact of inflammation on myopia has received rising attention in recent years. Elevated inflammation may contribute to myopia progression either directly or indirectly by inducing scleral remodeling, and myopia development may also increase ocular inflammation. This article provides a comprehensive review of the interplay between inflammation and myopia and the potential biological mechanisms, which may present new targets for understanding the pathology of myopia and developing myopia therapies.

Exosomes as cutting-edge therapeutics in various biomedical applications: An update on engineering, delivery, and preclinical studies

Exosomes are cell-derived nanovesicles, circulating in different body fluids, and acting as an intercellular mechanism. They can be purified from culture media of different cell types and carry an enriched content of various protein and nucleic acid molecules originating from their parental cells. It was indicated that the exosomal cargo can mediate immune responses via many signaling pathways. Over recent years, the therapeutic effects of various exosome types were broadly investigated in many preclinical studies. Herein, we present an update on recent preclinical studies on exosomes as therapeutic and/or delivery agents for various applications. The exosome origin, structural modifications, natural or loaded active ingredients, size, and research outcomes were summarized for various diseases. Overall, the present article provides an overview of the latest exosome research interests and developments to clear the way for the clinical study design and application.

Potential of mesenchymal stem cell-derived conditioned medium/secretome as a therapeutic option for ocular diseases

Research has shown that the therapeutic effect of mesenchymal stem cells (MSCs) is partially due to its secreted factors as opposed to the implantation of the cells into the treated tissue or tissue replacement. MSC secretome, especially in the form of conditioned medium (MSC-CM) is now being explored as an alternative to MSCs transplantation. Despite the observed benefits of MSC-CM, only a few clinical trials have evaluated it and other secretome components in the treatment of eye diseases. This review provides insight into the potential therapeutic use of MSC-CM in eye conditions, such as corneal diseases, dry eye, glaucoma, retinal diseases and uveitis. We discuss the current evidence, some limitations, and the progress that remains to be achieved before clinical translation becomes possible.

The Truth Is Out There: Biological Features and Clinical Indications of Extracellular Vesicles from Human Perinatal Stem Cells

The potential of perinatal tissues to provide cellular populations to be used in different applications of regenerative medicine is well established. Recently, the efforts of researchers are being addressed regarding the evaluation of cell products (secreted molecules or extracellular vesicles, EVs) to be used as an alternative to cellular infusion. The data regarding the effective recapitulation of most perinatal cells' properties by their secreted complement point in this direction. EVs secreted from perinatal cells exhibit key therapeutic effects such as tissue repair and regeneration, the suppression of inflammatory responses, immune system modulation, and a variety of other functions. Although the properties of EVs from perinatal derivatives and their significant potential for therapeutic success are amply recognized, several challenges still remain that need to be addressed. In the present review, we provide an up-to-date analysis of the most recent results in the field, which can be addressed in future research in order to overcome the challenges that are still present in the characterization and utilization of the secreted complement of perinatal cells and, in particular, mesenchymal stromal cells.

Enhanced therapeutic effect of PEDF-loaded mesenchymal stem cell-derived small extracellular vesicles against oxygen-induced retinopathy through increased stability and penetrability of PEDF

BACKGROUND

Several common retinal diseases that cause blindness are characterised by pathological neovascularisation accompanied by inflammation and neurodegeneration, including retinopathy of prematurity (ROP), diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinal vein occlusion (RVO). The current treatment strategies for these diseases have limited benefits. Thus, safer and more effective alternative approaches are required. In this study, we loaded small extracellular vesicles (sEVs) derived from mesenchymal stem cell (MSC) with pigment epithelium-derived factor (PEDF), and tested the therapeutic effect of PEDF-loaded sEVs (PEDF-sEVs) using an oxygen induced retinopathy (OIR) mouse model, aiming to establish a new therapy strategy for the treatment of retinal pathological angiogenesis.

RESULTS

We formulated PEDF-loaded sEVs (PEDF-sEVs) containing high concentrations of PEDF and evaluated their effects through in vivo and in vitro experiments. In OIR mice, PEDF-sEVs showed significantly better effects on retinal avascular areas, inflammation, and neuronal degeneration compared with the anti-vascular endothelial growth factor (VEGF) drug, which may indicate a possible advantage of PEDF-sEVs over anti-VEGF drugs in the treatment of pathological neovascularisation. In vitro, PEDF-sEVs greatly inhibited endothelial cell (EC) proliferation, migration, and tube formation by suppressing the VEGF-induced phosphorylation of extracellular signal-regulated kinase (ERK) and AKT (also known as Protein Kinase B). All experiments and analyses were performed in triplicate. PEDF-sEVs were more effective than PEDF or sEVs alone, both in vitro and in vivo. Furthermore, to determine the distribution of PEDF-sEVs, we used DiD-labelled sEVs and FITC-labelled PEDF to track the sEVs and PEDF, respectively. We found that PEDF-sEVs effectively reduced the degradation of PEDF.

CONCLUSIONS

Loading PEDF on sEVs effectively enhanced the anti-angiogenic, anti-inflammatory, and neuroprotective effects of PEDF by increasing the stability and penetrability. These results suggest a potential role for PEDF-sEVs in retinal pathological neovascularisation.

A bibliometric systematic review of extracellular vesicles in eye diseases from 2003 to 2022

BACKGROUND

Extracellular vesicles (EVs) have emerged as a valuable and promising research field in eye diseases. However, there are few bibliometric studies in this area. The purpose of this study was to employ bibliometric analysis to visualize the research hotspots and trends of EVs in eye diseases and provide researchers with new perspectives for further studies.

METHODS

Articles and reviews on EVs in eye diseases published between January 1, 2003 and December 31, 2022 were retrieved from the Web of Science Core Collection. Qualitative and quantitative analysis was performed using Microsoft Excel and CiteSpace software.

RESULTS

In total, 790 articles were included in the analysis. Over the past 2 decades, there has been a significant increase in the number of publications on the study of EVs in eye diseases. The United States, China, and Italy made the most significant contributions to this field. The Chinese Academy of Sciences was the most productive institution, and International Journal of Molecular Sciences published the most number of articles. Proceedings of the National Academy of Sciences of the United States of America had the highest citation frequency. Beit-Yannai E had the highest output and Thery C had the highest average citation frequency among authors. The analysis of keywords revealed that the neuroprotective effects of stem cell-derived EVs and biomarkers of eye diseases are current research hotspots and frontiers in this field.

CONCLUSION

This study provides a scientific perspective on EVs in eye diseases and provides valuable information for researchers to detect current research conditions, hotspots, and emerging trends for further study.

Preventive Effects of Exosome-Rich Conditioned Medium From Amniotic Membrane-Derived Mesenchymal Stem Cells for Diabetic Retinopathy in Rats

Purpose

Diabetic retinopathy (DR) is an important disease that causes vision loss in many diabetic patients. Stem cell therapy has been attempted for treatment of this disease; however, it has some limitations. This study aimed to evaluate the preventive efficacy of exosome-rich conditioned medium (ERCM) derived from amniotic membrane stem cells for DR in rats.

Methods

Twenty-eight 8-week-old male Sprague-Dawley rats were divided into three groups: group 1, normal control (Con) group; group 2, diabetes mellitus (DM) group; and group 3, DM with ERCM-treated (DM-ERCM) group. DM was induced by intraperitoneal injection of streptozotocin. The DM-ERCM group received ERCM containing 1.2 × 10⁹ exosomes into subconjunctival a total of four times every 2 weeks.

Results

On electroretinogram, the DM-ERCM group had significantly higher b-wave and flicker amplitudes than those in the DM group. In fundoscopy, retinal vascular attenuation was found in both the DM and DM-ERCM groups; however, was more severe in the DM group. On histology, the ganglion cell and nerve fiber layer rates of the total retinal layer significantly increased in the DM group compared with the Con group, whereas the DM-ERCM group showed no significant difference compared with the Con group. Cataracts progressed significantly more in the DM group than that in the DM-ERCM group and there was no uveitis in the DM-ERCM group.

Conclusions

Subconjunctival ERCM delayed the progression of DR and cataracts and significantly reduced the incidence of uveitis.

Translational Relevance

Our study shows the clinical potential of minimally invasive exosome-rich conditioned medium treatment to prevent diabetic retinopathy.

Advances in development of exosomes for ophthalmic therapeutics

Exosomes contain multiple bioactive molecules and maintain the connection between cells. Recent advances in exosome-based therapeutics have witnessed unprecedented opportunities in treating ophthalmic diseases, including traumatic diseases, autoimmune diseases, chorioretinal diseases and others. Utilization of exosomes as delivery vectors to encapsulate both drugs and therapeutic genes could yield higher efficacy and avoid the unnecessary immune responses. However, exosome-based therapies also come with some potential ocular risks. In this review, we first present a general introduction to exosomes. Then we provide an overview of available applications and discuss their potential risks. Moreover, we review recently reported exosomes as delivery vectors for ophthalmic diseases. Finally, we put forward future perspectives to grapple with its translation and underlying issues.

Pathological role of inflammation in ocular disease progress and its targeting by mesenchymal stem cells (MSCs) and their exosome; current status and prospect

Because of their unique capacity for differentiation to a diversity of cell lineages and immunosuppressive properties, mesenchymal stem cells (MSC) are being looked at as a potential new treatment option in ophthalmology. The MSCs derived from all tissue sources possess immunomodulatory attributes through cell-to-cell contact and releasing a myriad of immunomodulatory factors (IL-10, TGF-β, growth-related oncogene (GRO), indoleamine 2,3 dioxygenase (IDO), nitric oxide (NO), interleukin 1 receptor antagonist (IL-1Ra), prostaglandin E2 (PGE2)). Such mediators, in turn, alter both the phenotype and action of all immune cells that serve a pathogenic role in the progression of inflammation in eye diseases. Exosomes from MSCs, as natural nano-particles, contain the majority of the bioactive components of parental MSCs and can easily by-pass all biological barriers to reach the target epithelial and immune cells in the eye without interfering with nearby parenchymal cells, thus having no serious side effects. We outlined the most recent research on the molecular mechanisms underlying the therapeutic benefits of MSC and MSC-exosome in the treatment of inflammatory eye diseases in the current article.

Mesenchymal Stem Cells and Exosomes: A Novel Therapeutic Approach for Corneal Diseases

The cornea, with its delicate structure, is vulnerable to damage from physical, chemical, and genetic factors. Corneal transplantation, including penetrating and lamellar keratoplasties, can restore the functions of the cornea in cases of severe damage. However, the process of corneal transplantation presents considerable obstacles, including a shortage of available donors, the risk of severe graft rejection, and potentially life-threatening complications. Over the past few decades, mesenchymal stem cell (MSC) therapy has become a novel alternative approach to corneal regeneration. Numerous studies have demonstrated the potential of MSCs to differentiate into different corneal cell types, such as keratocytes, epithelial cells, and endothelial cells. MSCs are considered a suitable candidate for corneal regeneration because of their promising therapeutic perspective and beneficial properties. MSCs compromise unique immunomodulation, anti-angiogenesis, and anti-inflammatory properties and secrete various growth factors, thus promoting corneal reconstruction. These effects in corneal engineering are mediated by MSCs differentiating into different lineages and paracrine action via exosomes. Early studies have proven the roles of MSC-derived exosomes in corneal regeneration by reducing inflammation, inhibiting neovascularization, and angiogenesis, and by promoting cell proliferation. This review highlights the contribution of MSCs and MSC-derived exosomes, their current usage status to overcome corneal disease, and their potential to restore different corneal layers as novel therapeutic agents. It also discusses feasible future possibilities, applications, challenges, and opportunities for future research in this field.

Biogenesis, Composition and Potential Therapeutic Applications of Mesenchymal Stem Cells Derived Exosomes in Various Diseases

Exosomes are nanovesicles with a wide range of chemical compositions used in many different applications. Mesenchymal stem cell-derived exosomes (MSCs-EXOs) are spherical vesicles that have been shown to mediate tissue regeneration in a variety of diseases, including neurological, autoimmune and inflammatory, cancer, ischemic heart disease, lung injury, and liver fibrosis. They can modulate the immune response by interacting with immune effector cells due to the presence of anti-inflammatory compounds and are involved in intercellular communication through various types of cargo. MSCs-EXOs exhibit cytokine storm-mitigating properties in response to COVID-19. This review discussed the potential function of MSCs-EXOs in a variety of diseases including neurological, notably epileptic encephalopathy and Parkinson's disease, cancer, angiogenesis, autoimmune and inflammatory diseases. We provided an overview of exosome biogenesis and factors that regulate exosome biogenesis. Additionally, we highlight the functions and potential use of MSCs-EXOs in the treatment of the inflammatory disease COVID-19. Finally, we covered a strategies and challenges of MSCs-EXOs. Finally, we discuss conclusion and future perspectives of MSCs-EXOs.

Wound-Healing Effects of Mesenchymal Stromal Cell Secretome in the Cornea and the Role of Exosomes

Mesenchymal stromal/stem cells (MSCs) and their secreted factors have been shown to have immunomodulatory and regenerative effects. In this study, we investigated human bone-marrow-derived MSC secretome (MSC-S) for the treatment of corneal epithelial wounds. Specifically, we evaluated the role of MSC extracellular vesicles (EV)/exosomes in mediating the wound-healing effects of the MSC-S. In vitro studies using human corneal epithelial cells showed that MSC-CM increased cell proliferation in HCEC and HCLE cells, while EV-depleted MSC-CM showed lower cell proliferation in both cell lines compared to the MSC-CM group. In vitro and in vivo experiments revealed that 1X MSC-S consistently promoted wound healing more effectively than 0.5X MSC-S, and MSC-CM promoted wound healing in a dose-dependent manner, while exosome deprivation delayed wound healing. We further evaluated the incubation period of MSC-CM on corneal wound healing and showed that MSC-S collected for 72 h is more effective than MSC-S collected for 48 h. Finally, we evaluated the stability of MSC-S under different storage conditions and found that after one cycle of freeze-thawing, MSC-S is stable at 4 °C for up to 4 weeks. Collectively, we identified the following: (i) MSC-EV/Exo as the active ingredient in MSC-S that mediates the wound-healing effects in the corneal epithelium, providing a measure to optimize its dosing for a potential clinical product; (ii) Treatment with EV/Exo-containing MSC-S resulted in an improved corneal barrier and decreased corneal haze/edema relative to EV/Exo-depleted MSC-S; (iii) The stability of MSC-CM for up to 4 weeks showed that the regular storage condition did not significantly impact its stability and therapeutic functions.

BMSC reduces ROS and inflammation levels by inhibiting TLR4/MYD88/NF-κB signaling axis to alleviate dry eye

Objective To investigate the therapeutic effect of Bone marrow mesenchymal stem cells (BMSCs) on dry eye mice, and to investigate the mechanism of TLR4/MYD88/NF-κB signaling pathway on corneal injury repair in dry eye mice. Methods To establish a hypertonic dry eye cell model. Western blot for measureing the protein expressions of caspase-1, IL-1β，NLRP3 and ASC，and Rt-qpcr for mRNA expression. Flow cytometry for detecting the ROS content and apoptosis rate. CCK-8 for detecting the proliferation activity of cells, and ELISA for the levels of inflammation-related factors.The levels of inflammation-related factors were detected by ELISA. The dry eye mouse model of benzalkonium chloride was established. Three clinical parameters used to evaluate ocular surface damage, namely tear secretion, tear film rupture time and corneal sodium fluorescein staining, were measured with phenol cotton thread. Flow cytometry and TUNEL staining are both for he apoptosis rate. Western blot also for detecting the protein expressions of TLR4, MYD88, NF-κB, inflammation-related factors and apoptosis-related factors . The pathological changes were evaluated by HE and PAS staining. Results In vitro, BMSCs and inhibitors of TLR4, MYD88 and NF-κB showed decreased ROS content, decreased inflammatory factor protein level, decreased apoptotic protein level and increased mRNA expression compared with NaCl group. BMSCS partially reversed cell apoptosis induced by NaCl and improved cell proliferation. In vivo, it reduces corneal epithelial defects, goblet cell loss and inflammatory cytokine production, and increases tear production. In vitro, BMSC and inhibitors of TLR4, MYD88 and NF-κB could protect mice from apoptosis induced by hypertonic stress. In terms of mechanism, NACL-induced NLRP3 inflammasome formation, caspase-1 activation and IL-1β maturation can be inhibited. Conclusion BMSCs treatment can reduce ROS and inflammation levels and alleviate dry eye by inhibiting TLR4/MYD88/NF-κBsignaling pathway.

Mesenchymal Stem Cell Exosomes as Immunomodulatory Therapy for Corneal Scarring

Corneal scarring is a leading cause of worldwide blindness. Human mesenchymal stem cells (MSC) have been reported to promote corneal wound healing through secreted exosomes. This study investigated the wound healing and immunomodulatory effects of MSC-derived exosomes (MSC-exo) in corneal injury through an established rat model of corneal scarring. After induction of corneal scarring by irregular phototherapeutic keratectomy (irrPTK), MSC exosome preparations (MSC-exo) or PBS vehicle as controls were applied to the injured rat corneas for five days. The animals were assessed for corneal clarity using a validated slit-lamp haze grading score. Stromal haze intensity was quantified using in-vivo confocal microscopy imaging. Corneal vascularization, fibrosis, variations in macrophage phenotypes, and inflammatory cytokines were evaluated using immunohistochemistry techniques and enzyme-linked immunosorbent assays (ELISA) of the excised corneas. Compared to the PBS control group, MSC-exo treatment group had faster epithelial wound closure (0.041), lower corneal haze score (p = 0.002), and reduced haze intensity (p = 0.004) throughout the follow-up period. Attenuation of corneal vascularisation based on CD31 and LYVE-1 staining and reduced fibrosis as measured by fibronectin and collagen 3A1 staining was also observed in the MSC-exo group. MSC-exo treated corneas also displayed a regenerative immune phenotype characterized by a higher infiltration of CD163+, CD206+ M2 macrophages over CD80+, CD86+ M1 macrophages (p = 0.023), reduced levels of pro-inflammatory IL-1β, IL-8, and TNF-α, and increased levels of anti-inflammatory IL-10. In conclusion, topical MSC-exo could alleviate corneal insults by promoting wound closure and reducing scar development, possibly through anti-angiogenesis and immunomodulation towards a regenerative and anti-inflammatory phenotype.

The molecular mechanism of human stem cell-derived extracellular vesicles in retinal repair and regeneration

Extracellular vesicles (EVs), including microvesicles (MVs) and exosomes, play a critical role in metabolic regulation and intracellular communication. Stem cell-derived EVs are considered to have the potential for regeneration, like stem cells, while simultaneously avoiding the risk of immune rejection or tumour formation. The therapeutic effect of stem cell-derived EVs has been proven in many diseases. However, the molecular mechanism of stem cell-derived EVs in retinal repair and regeneration has not been fully clarified. In this review, we described the biological characteristics of stem cell-derived EVs, summarized the current research on stem cell-derived EV treatment in retinal repair and regeneration, and discussed the potential and challenges of stem cell-derived EVs in translational medicine.

Mesenchymal stromal/stem cell (MSC)-derived exosomes in clinical trials

Mesenchymal stromal/stem cells (MSCs) are widely utilized in cell therapy because of their robust immunomodulatory and regenerative properties. Their paracrine activity is one of the most important features that contribute to their efficacy. Recently, it has been demonstrated that the production of various factors via extracellular vesicles, especially exosomes, governs the principal efficacy of MSCs after infusion in experimental models. Compared to MSCs themselves, MSC-derived exosomes (MSC-Exos) have provided significant advantages by efficiently decreasing unfavorable adverse effects, such as infusion-related toxicities. MSC-Exos is becoming a promising cell-free therapeutic tool and an increasing number of clinical studies started to assess the therapeutic effect of MSC-Exos in different diseases. In this review, we summarized the ongoing and completed clinical studies using MSC-Exos for immunomodulation, regenerative medicine, gene delivery, and beyond. Additionally, we summarized MSC-Exos production methods utilized in these studies with an emphasis on MSCs source, MSC-Exos isolation methods, characterization, dosage, and route of administration. Lastly, we discussed the current challenges and future directions of exosome utilization in different clinical studies as a novel therapeutic strategy.

Mesenchymal Stem Cell-Derived Exosomes in Ophthalmology: A Comprehensive Review

Over the past decade, the field of mesenchymal stem cell (MSC) therapy has exhibited rapid growth. Due to their regenerative, reparatory, and immunomodulatory capacities, MSCs have been widely investigated as therapeutic agents in the cell-based treatment of chronic ophthalmic pathologies. However, the applicability of MSC-based therapy is limited by suboptimal biocompatibility, penetration, and delivery to the target ocular tissues. An emerging body of research has elucidated the role of exosomes in the biological functions of MSCs, and that MSC-derived extracellular vesicles (EVs) possess anti-inflammatory, anti-apoptotic, tissue repairing, neuroprotective, and immunomodulatory properties similar to MSCs. The recent advances in MSCs-derived exosomes can serve as solutions to the challenges faced by MSCs-therapy. Due to their nano-dimensions, MSC-derived exosomes can rapidly penetrate biological barriers and reach immune-privileged organs, allowing for efficient delivery of therapeutic factors such as trophic and immunomodulatory agents to ocular tissues that are typically challenging to target by conventional therapy and MSCs transplantation. In addition, the use of EVs minimizes the risks associated with mesenchymal stem cell transplantation. In this literature review, we focus on the studies published between 2017 and 2022, highlighting the characteristics of EVs derived from MSCs and their biological functions in treating anterior and posterior segment ocular diseases. Additionally, we discuss the potential use of EVs in clinical settings. Rapid advancements in regenerative medicine and exosome-based drug delivery, in conjunction with an increased understanding of ocular pathology and pharmacology, hold great promise for the treatment of ocular diseases. The potential of exosome-based therapies is exciting and can revolutionize the way we approach these ocular conditions.

Biophysical, Molecular and Proteomic Profiling of Human Retinal Organoid-Derived Exosomes

PURPOSE

There is a growing interest in extracellular vesicles (EVs) for ocular applications as therapeutics, biomarkers, and drug delivery vehicles. EVs secreted from mesenchymal stem cells (MSCs) have shown to provide therapeutic benefits in ocular conditions. However, very little is known about the properties of bioreactor cultured-3D human retinal organoids secreted EVs. This study provides a comprehensive morphological, nanomechanical, molecular, and proteomic characterization of retinal organoid EVs and compares it with human umbilical cord (hUC) MSCs.

METHODS

The morphology and nanomechanical properties of retinal organoid EVs were assessed using Nanoparticle tracking analysis (NTA) and Atomic force microscopy (AFM). Gene expression analysis of exosome biogenesis of early and late retinal organoids were compared using qPCR. The protein profile of the EVs were analyzed with proteomic tools.

RESULTS

NTA indicated the average size of EV as 100-250 nm. A high expression of exosome biogenesis genes was observed in late retinal organoids EVs. Immunoblot analysis showed highly expressed exosomal markers in late retinal organoids EVs compared to early retinal organoids EVs. Protein profiling of retinal organoid EVs displayed a higher differential expression of retinal function-related proteins and EV biogenesis proteins than hUCMSC EVs, implicating that the use of retinal organoid EVs may have a superior therapeutic effect on retinal disorders.

CONCLUSION

This study provides supplementary knowledge on the properties of retinal organoid EVs and suggests their potential use in the diagnostic and therapeutic treatments for ocular diseases.

Salivary Exosomes in Health and Disease: Future Prospects in the Eye

Exosomes are a group of vesicles that package and transport DNA, RNA, proteins, and lipids to recipient cells. They can be derived from blood, saliva, urine, and/or other biological tissues. Their impact on several diseases, such as neurodegenerative, autoimmune, and ocular diseases, have been reported, but not fully unraveled. The exosomes that are derived from saliva are less studied, but offer significant advantages over exosomes from other sources, due to their accessibility and ease of collection. Thus, their role in the pathophysiology of diseases is largely unknown. In the context of ocular diseases, salivary exosomes have been under-utilized, thus creating an enormous gap in the literature. The current review discusses the state of exosomes research on systemic and ocular diseases and highlights the role and potential of salivary exosomes as future ocular therapeutic vehicles.

Mesenchymal stem cell-derived extracellular vesicles subvert Th17 cells by destabilizing RORγt through posttranslational modification

Mesenchymal stem cell (MSC)-derived small extracellular vesicles (MSC-sEVs) are known to exert immunosuppressive functions. This study showed that MSC-sEVs specifically convert T helper 17 (Th17) cells into IL-17 low-producer (ex-Th17) cells by degrading RAR-related orphan receptor γt (RORγt) at the protein level. In experimental autoimmune encephalomyelitis (EAE)-induced mice, treatment with MSC-sEVs was found to not only ameliorate clinical symptoms but also to reduce the number of Th17 cells in draining lymph nodes and the central nervous system. MSC-sEVs were found to destabilize RORγt by K63 deubiquitination and deacetylation, which was attributed to the EP300-interacting inhibitor of differentiation 3 (Eid3) contained in the MSC-sEVs. Small extracellular vesicles isolated from the Eid3 knockdown MSCs by Eid3-shRNA failed to downregulate RORγt. Moreover, forced expression of Eid3 by gene transfection was found to significantly decrease the protein level of RORγt in Th17 cells. Altogether, this study reveals the novel immunosuppressive mechanisms of MSC-sEVs, which suggests the feasibility of MSC-sEVs as an attractive therapeutic tool for curing Th17-mediated inflammatory diseases.

Extracellular Vesicles as reconfigurable therapeutics for eye diseases: Promises and hurdles

A large number of people worldwide suffer from visual impairment. However, most available therapies rely on impeding the development of a particular eye disorder. Therefore, there is an increasing demand for effective alternative treatments, specifically regenerative therapies. Extracellular vesicles, including exosomes, ectosomes, or microvesicles, are released by cells and play a potential role in regeneration. Following an introduction to EV biogenesis and isolation methods, this integrative review provides an overview of our current knowledge about EVs as a communication paradigm in the eye. Then, we focused on the therapeutic applications of EVs derived from conditioned medium, biological fluid, or tissue and highlighted some recent developments in strategies to boost the innate therapeutic potential of EVs by loading various kinds of drugs or being engineered at the level of producing cells or EVs. Challenges faced in the development of safe and effective translation of EV-based therapy into clinical settings for eye diseases are also discussed to pave the road toward reaching feasible regenerative therapies required for eye-related complications.

Extracellular vesicles as a new horizon in the diagnosis and treatment of inflammatory eye diseases: A narrative review of the literature

Extracellular vesicles include exosomes, microvesicles, and apoptotic bodies. Their cargos contain a diverse variety of lipids, proteins, and nucleic acids that are involved in both normal physiology and pathology of the ocular system. Thus, studying extracellular vesicles may lead to a more comprehensive understanding of the pathogenesis, diagnosis, and even potential treatments for various diseases. The roles of extracellular vesicles in inflammatory eye disorders have been widely investigated in recent years. The term “inflammatory eye diseases” refers to a variety of eye conditions such as inflammation-related diseases, degenerative conditions with remarkable inflammatory components, neuropathy, and tumors. This study presents an overview of extracellular vesicles’ and exosomes’ pathogenic, diagnostic, and therapeutic values in inflammatory eye diseases, as well as existing and potential challenges.

Human umbilical cord mesenchymal stem cells-derived exosomal circDLGAP4 promotes angiogenesis after cerebral ischemia-reperfusion injury by regulating miR-320/KLF5 axis

Accumulating evidence suggests that human umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSCs-Exos) are a promising therapeutic strategy for cerebral ischemia-reperfusion injury (CIRI). However, the underlying mechanism remains unclear. hUC-MSCs-Exos were identified by electron microscopy, NTA, and Western blotting. In the hypoxia/reoxygenation (H/R) cell model, human brain microvascular endothelial cells (HBMECs) were cocultured with hUC-MSCs-Exos. Then, cell viability, migration, apoptosis, and tube formation were measured by MTT, flow cytometry, transwell, and tube formation assays. RT-qPCR and Western blotting were used to detect the changes in RNA and protein. RNA pull-down and dual luciferase reporter assays confirmed the relationship between circDLGAP4, miR-320, and KLF5. Ischemia-reperfusion (I/R) rat model was established for in vivo experiments. hUC-MSCs-Exos increased the expression levels of circDLGAP4 and KLF5 but decreased miR-320 in H/R-treated HBMECs by transferring exosomal circDLGAP4. Knockdown of circDLGAP4 in hUC-MSCs-Exos reversed the promoting effects of hUC-MSCs-Exos on cell viability, migration, and tube formation in H/R-treated HBMECs in vitro and also abolished the protective effects of hUC-MSCs-Exos on cerebrovascular injury in I/R rats. Mechanistically, exosomal circDLGAP4 negatively regulated miR-320 in HBMECs, which directly bound to KLF5. In addition, the downregulation of miR-320 could reverse the regulatory effect of exosomal shcircDLGAL5 in H/R-treated HBMECs by upregulating KLF5. hUC-MSCs-Exos-derived circDLGAP4 reduced cerebrovascular injury by regulating miR-320/KLF5 signaling. These results provide a stem cell-based approach to treat CIRI.

In vitro treatment of murine splenocytes with extracellular vesicles derived from mesenchymal stem cells altered the mRNA levels of the master regulator genes of T helper cell subsets

INTRODUCTION

The purpose of the current study was to evaluate the effect of mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) on the production of cytokines and expression of genes, which are corresponded to the subsets of T helper cells.

MATERIALS AND METHODS

The supernatant of the second passage of MSCs that had been isolated from C57BL/6 mice abdominal adipose tissue was used to collect the MSC-EV. Splenocytes of healthy mice were activated using anti-CD3 and anti-CD28 antibodies and simultaneously were treated using the MSC-EVs. The proliferation rate of lymphocytes and the frequency of regulatory T cells were measured using flow cytometry. In addition, the expressions of T helper cell subset-specific transcription factors were evaluated using a real-time PCR assay. To appraise the effects of MSC-EV on splenocytes, the levels of IFN-γ, IL-17A, IL-10, and TGF-β were measured using ELISA.

RESULTS

The results showed that the treatment of the CD3/CD28-activated splenocytes with MSC-EV did not statistically change the proliferation of CD3⁺ splenocytes. However, after the treatment, the mRNA levels of Foxp3 and Elf4 as well as the frequency of regulatory T cells was significantly higher when compared to the control group. The expression levels of Gata3, Rorc, and Tbx21 were down-regulated while, the corresponding cytokines levels did not alter.

CONCLUSION

The results revealed that the in vitro treatment of MSC-EV was associated with the increase in the frequency of CD4⁺CD25⁺FOXP3⁺ T cells and upregulation of Foxp3 mRNA level.

A synergistic therapeutic nano-eyedrop for dry eye disease based on ascorbic acid-coupled exosomes

Dry eye disease (DED), a complex ocular surface disease with a high prevalence rate, is associated with corneal injury, excess oxidative stress and inflammation. Current therapeutic strategies, including artificial tears and anti-inflammatory agents, are unable to address all the deleterious factors or to achieve a clinical cure due to their temporary or side effects. Here, we prepared a multiple-functional eyedrop based on the deposition of gold nanoparticles (AuNPs) reduced by ascorbic acid (AA) onto the exosomal phospholipid membrane of mesenchymal stem cell (mExo)-derived exosomes in situ (mExo@AA). The therapeutic value of mExo@AA for DED was demonstrated in a mouse DED model. Combining the benefits of mExo and AA, mExo@AA effectively improves corneal epithelium recovery and anti-inflammation capacity, decreases corneal reactive oxygen species, and restores tear secretion without adverse effects. Thus, this study suggests that mExo@AA is effective and safe as a therapeutic agent for the treatment of DED.

Research progress of exosomes in pathogenesis, diagnosis, and treatment of ocular diseases

Exosomes are natural extracellular vesicles with a diameter of 30-150 nm, which exist in biological fluids and contain biomolecules related to the parent cell, such as proteins, nucleic acids, lipids, etc. It has a wide range of biological functions, and participates in the regulation of important physiological and pathological activities of the body. It can be used as a biomarker for early diagnosis of ocular diseases, a potential therapeutic target, a targeted drug carrier, and has a high potential for clinical application. In this paper, we summarized the genesis mechanism, biological functions, research and application progress of exosomes, focused on the engineering strategy of exosomes, and summarized the advantages and disadvantages of common engineering exosome preparation methods. Systematically combed the role of exosomes in corneal diseases, glaucoma, and retinal diseases, to provide a reference for further understanding of the role of exosomes in the pathogenesis, diagnosis, and treatment of ocular diseases. Finally, we further summarized the opportunities and challenges of exosomes for precision medicine. The extension of exosome research to the field of ophthalmology will help advance current diagnostic and therapeutic methods. Tiny exosomes have huge potential.

Extracellular Vesicles as Biomarkers and Therapeutics for Inflammatory Eye Diseases

Extracellular vesicles (EVs) are a group of cell-derived membrane vesicles of varying sizes that can be secreted by most cells. Depending on the type of cell they are derived from, EVs may contain a variety of cargo including proteins, lipids, miRNA, and DNA. Functionally, EVs play important roles in physiological and pathological processes through intercellular communication. While there has already been significant literature on the involvement of EVs in neurological and cardiovascular disease as well as cancer, recent evidence suggests that EVs may also play a role in mediating inflammatory eye diseases. This paper summarizes current advancements in ocular EV research as well as new ways by which EVs may be utilized as novel biomarkers of or therapeutics for inflammatory eye diseases.