Extracellular Vesicle-Associated Proteins in Tissue Repair

Role of aptamer technology in extracellular vesicle biology and therapeutic applications

Extracellular vesicles (EVs) are cell-derived nanosized membrane-bound vesicles that are important intercellular signalling regulators in local cell-to-cell and distant cell-to-tissue communication. Their inherent capacity to transverse cell membranes and transfer complex bioactive cargo reflective of their cell source, as well as their ability to be modified through various engineering and modification strategies, have attracted significant therapeutic interest. Molecular bioengineering strategies are providing a new frontier for EV-based therapy, including novel mRNA vaccines, antigen cross-presentation and immunotherapy, organ delivery and repair, and cancer immune surveillance and targeted therapeutics. The revolution of EVs, their diversity as biocarriers and their potential to contribute to intercellular communication, is well understood and appreciated but is ultimately dependent on the development of methods and techniques for their isolation, characterization and enhanced targeting. As single-stranded oligonucleotides, aptamers, also known as chemical antibodies, offer significant biological, chemical, economic, and therapeutic advantages in terms of their size, selectivity, versatility, and multifunctional programming. Their integration into the field of EVs has been contributing to the development of isolation, detection, and analysis pipelines associated with bioengineering strategies for nano-meets-molecular biology, thus translating their use for therapeutic and diagnostic utility.

Recent advances in the use of extracellular vesicles from adipose-derived stem cells for regenerative medical therapeutics

Adipose-derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) isolated from adipose tissue. They possess remarkable properties, including multipotency, self-renewal, and easy clinical availability. ADSCs are also capable of promoting tissue regeneration through the secretion of various cytokines, factors, and extracellular vesicles (EVs). ADSC-derived EVs (ADSC-EVs) act as intercellular signaling mediators that encapsulate a range of biomolecules. These EVs have been found to mediate the therapeutic activities of donor cells by promoting the proliferation and migration of effector cells, facilitating angiogenesis, modulating immunity, and performing other specific functions in different tissues. Compared to the donor cells themselves, ADSC-EVs offer advantages such as fewer safety concerns and more convenient transportation and storage for clinical application. As a result, these EVs have received significant attention as cell-free therapeutic agents with potential future application in regenerative medicine. In this review, we focus on recent research progress regarding regenerative medical use of ADSC-EVs across various medical conditions, including wound healing, chronic limb ischemia, angiogenesis, myocardial infarction, diabetic nephropathy, fat graft survival, bone regeneration, cartilage regeneration, tendinopathy and tendon healing, peripheral nerve regeneration, and acute lung injury, among others. We also discuss the underlying mechanisms responsible for inducing these therapeutic effects. We believe that deciphering the biological properties, therapeutic effects, and underlying mechanisms associated with ADSC-EVs will provide a foundation for developing a novel therapeutic approach in regenerative medicine.

hTERT-Immortalized Mesenchymal Stem Cell-Derived Extracellular Vesicles: Large-Scale Manufacturing, Cargo Profiling, and Functional Effects in Retinal Epithelial Cells

As the economic burden associated with vision loss and ocular damage continues to rise, there is a need to explore novel treatment strategies. Extracellular vesicles (EVs) are enriched with various biological cargo, and there is abundant literature supporting the reparative and immunomodulatory properties of stem cell EVs across a broad range of pathologies. However, one area that requires further attention is the reparative effects of stem cell EVs in the context of ocular damage. Additionally, most of the literature focuses on EVs isolated from primary stem cells; the use of EVs isolated from human telomerase reverse transcriptase (hTERT)-immortalized stem cells has not been thoroughly examined. Using our large-scale EV-manufacturing platform, we reproducibly manufactured EVs from hTERT-immortalized mesenchymal stem cells (MSCs) and employed various methods to characterize and profile their associated cargo. We also utilized well-established cell-based assays to compare the effects of these EVs on both healthy and damaged retinal pigment epithelial cells. To the best of our knowledge, this is the first study to establish proof of concept for reproducible, large-scale manufacturing of hTERT-immortalized MSC EVs and to investigate their potential reparative properties against damaged retinal cells. The results from our studies confirm that hTERT-immortalized MSC EVs exert reparative effects in vitro that are similar to those observed in primary MSC EVs. Therefore, hTERT-immortalized MSCs may represent a more consistent and reproducible platform than primary MSCs for generating EVs with therapeutic potential.

Applications of 3D Bioprinting Technology to Brain Cells and Brain Tumor Models: Special Emphasis to Glioblastoma

Primary brain tumor is one of the most fatal diseases. The most malignant type among them, glioblastoma (GBM), has low survival rates. Standard treatments reduce the life quality of patients due to serious side effects. Tumor aggressiveness and the unique structure of the brain render the removal of tumors and the development of new therapies challenging. To elucidate the characteristics of brain tumors and examine their response to drugs, realistic systems that mimic the tumor environment and cellular crosstalk are desperately needed. In the past decade, 3D GBM models have been presented as excellent platforms as they allowed the investigation of the phenotypes of GBM and testing innovative therapeutic strategies. In that scope, 3D bioprinting technology offers utilities such as fabricating realistic 3D bioprinted structures in a layer-by-layer manner and precisely controlled deposition of materials and cells, and they can be integrated with other technologies like the microfluidics approach. This Review covers studies that investigated 3D bioprinted brain tumor models, especially GBM using 3D bioprinting techniques and essential parameters that affect the result and quality of the study like frequently used cells, the type and physical characteristics of hydrogel, bioprinting conditions, cross-linking methods, and characterization techniques.

circCDK13-loaded small extracellular vesicles accelerate healing in preclinical diabetic wound models

Chronic wounds are a major complication in patients with diabetes. Here, we identify a therapeutic circRNA and load it into small extracellular vesicles (sEVs) to treat diabetic wounds in preclinical models. We show that circCDK13 can stimulate the proliferation and migration of human dermal fibroblasts and human epidermal keratinocytes by interacting with insulin-like growth factor 2 mRNA binding protein 3 in an N6-Methyladenosine-dependent manner to enhance CD44 and c-MYC expression. We engineered sEVs that overexpress circCDK13 and show that local subcutaneous injection into male db/db diabetic mouse wounds and wounds of streptozotocin-induced type I male diabetic rats could accelerate wound healing and skin appendage regeneration. Our study demonstrates that the delivery of circCDK13 in sEVs may present an option for diabetic wound treatment.

Extracellular vesicles as human therapeutics: A scoping review of the literature

Extracellular vesicles (EVs) are released by all cells and contribute to cell-to-cell communication. The capacity of EVs to target specific cells and to efficiently deliver a composite profile of functional molecules have led researchers around the world to hypothesize their potential as therapeutics. While studies of EV treatment in animal models are numerous, their actual clinical benefit in humans has more slowly started to be tested. In this scoping review, we searched PubMed and other databases up to 31 December 2023 and, starting from 13,567 records, we selected 40 pertinent published studies testing EVs as therapeutics in humans. The analysis of those 40 studies shows that they are all small pilot trials with a large heterogeneity in terms of administration route and target disease. Moreover, the absence of a placebo control in most of the studies, the predominant local application of EV formulations and the inconsistent administration dose metric still impede comparison across studies and firm conclusions about EV safety and efficacy. On the other hand, the recording of some promising outcomes strongly calls out for well-designed larger studies to test EVs as an alternative approach to treat human diseases with no or few therapeutic options.

First-in-man use of a cardiovascular cell-derived secretome in heart failure. Case report

BACKGROUND

There is increased evidence that the effects of stem cells can mostly be duplicated by administration of their secretome which might streamline the translation towards the clinics.

METHODS

The 12-patient SECRET-HF phase 1 trial has thus been designed to determine the feasibility and safety of repeated intravenous injections of the extracellular vesicle (EV)-enriched secretome of cardiovascular progenitor cells differentiated from pluripotent stem cells in severely symptomatic patients with drug-refractory left ventricular (LV) dysfunction secondary to non-ischemic dilated cardiomyopathy. Here we report the case of the first treated patient (baseline NYHA class III; LV Ejection Fraction:25%) in whom a dose of 20 × 109 particles/kg was intravenously infused three times three weeks apart.

FINDINGS

In addition to demonstrating the feasibility of producing a cardiac cell secretome compliant with Good Manufacturing Practice standards, this case documents the excellent tolerance of its repeated delivery, without any adverse events during or after infusions. Six months after the procedure, the patient is in NYHA Class II with improved echo parameters, a reduced daily need for diuretics (from 240 mg to 160 mg), no firing from the previously implanted automatic internal defibrillator and no alloimmunization against the drug product, thereby supporting its lack of immunogenicity.

INTERPRETATION

The rationale underlying the intravenous route is that the infused EV-enriched secretome may act by rewiring endogenous immune cells, both circulating and in peripheral organs, to take on a reparative phenotype. These EV-modified immune cells could then traffic to the heart to effect tissue repair, including mitigation of inflammation which is a hallmark of cardiac failure.

FUNDING

This trial is funded by the French Ministry of Health (Programme Hospitalier de Recherche CliniqueAOM19330) and the "France 2030" National Strategy Program (ANR-20-F2II-0003). It is sponsored by Assistance Publique-Hôpitaux de Paris.

A roadmap towards manufacturing extracellular vesicles for cardiac repair

For the past two decades researchers have linked extracellular vesicle (EV)-mediated mechanisms to various physiological and pathological processes in the heart, such as immune response regulation, fibrosis, angiogenesis, and the survival and growth of cardiomyocytes. Although use of EVs has gathered momentum in the cardiac field, several obstacles in both upstream and downstream processes during EV manufacture need to be addressed before clinical success can be achieved. Low EV yields obtained in small-scale cultures deter clinical translation, as mass production is a prerequisite to meet therapeutic doses. Moreover, standardizing EV manufacture is critical given the inherent heterogeneity of EVs and the constraints of current isolation techniques. In this review, we discuss the critical steps for the large-scale manufacturing of high-potency EVs for cardiac therapies.

Exosomal hsa_circ_0093884 derived from endothelial progenitor cells promotes therapeutic neovascularization via miR-145/SIRT1 pathway

Therapeutic neovascularization is a strategy to promote blood vessel growth and improve blood flow, which is critical to tissue repair and regeneration in ischemic diseases. Here, we investigated the role of endothelial progenitor cell - derived exosomes (EPC-Exos) in therapeutic neovascularization and clarified the mechanism of hsa_circ_0093884 in EPC-Exos mediated neovascularization. Injection of EPC-Exos improved mouse ischemic hindlimb perfusion, promoted angiogenesis in Matrigel plugs and mouse skin wound healing. In vitro coculture with EPC-Exos improved HUVEC proliferation, angiogenic and migration ability, while alleviated hypoxia-induced apoptosis. hsa_circ_0093884 was identified from eleven types of circRNA derived from SIRT1 and proved to be enriched in EPC-Exos. Overexpression of hsa_circ_0093884 in EPC-Exos further enhanced the angiogenic capacity, while knockdown of hsa_circ_0093884 abolished the benefits. Mechanistically, EPC-Exos mediated shuttling of hsa_circ_0093884 induced cytoplasmic sponge of miR-145, thereby releasing repression of SIRT1. In vitro co-transfection indicated silence of miR-145 further strengthened the angiogenic effect of hsa_circ_0093884, while overexpression of miR-145 inhibited hsa_circ_0093884 mediated angiogenesis and abolished the beneficial effect of EPC-Exos. Furthermore, in vivo experiments using endothelial specific SIRT1 conditional knockout mice indicated hsa_circ_0093884 overexpressing EPC-Exos failed to promote therapeutic neovascularization in SIRT1cKO mice. Collectively, our results demonstrated that EPC-Exos promoted therapeutic neovascularization through hsa_circ_0093884/miR-145/SIRT1 axis.

Immune cell-derived extracellular vesicles for precision therapy of inflammatory-related diseases

Inflammation-related diseases impose a significant global health burden, necessitating urgent exploration of novel treatment modalities for improved clinical outcomes. We begin by discussing the limitations of conventional approaches and underscore the pivotal involvement of immune cells in the inflammatory process. Amidst the rapid growth of immunology, the therapeutic potential of immune cell-derived extracellular vesicles (EVs) has garnered substantial attention due to their capacity to modulate inflammatory response. We provide an in-depth examination of immune cell-derived EVs, delineating their promising roles across diverse disease conditions in both preclinical and clinical settings. Additionally, to direct the development of the next-generation drug delivery systems, we comprehensively investigate the engineered EVs on their advanced isolation methods, cargo loading techniques, and innovative engineering strategies. This review ends with a focus on the prevailing challenges and considerations regarding the clinical translation of EVs in future, emphasizing the need of standardized characterization and scalable production processes. Ultimately, immune cell-derived EVs represent a cutting-edge therapeutic approach and delivery platform, holding immense promise in precision medicine.

Mesenchymal stem cells and ferroptosis: Clinical opportunities and challenges

Objective

This review discusses recent experimental and clinical findings related to ferroptosis, with a focus on the role of MSCs. Therapeutic efficacy and current applications of MSC-based ferroptosis therapies are also discussed.

Background

Ferroptosis is a type of programmed cell death that differs from apoptosis, necrosis, and autophagy; it involves iron metabolism and is related to the pathogenesis of many diseases, such as Parkinson's disease, cancers, and liver diseases. In recent years, the use of mesenchymal stem cells (MSCs) and MSC-derived exosomes has become a trend in cell-free therapies. MSCs are a heterogeneous cell population isolated from a diverse range of human tissues that exhibit immunomodulatory functions, regulate cell growth, and repair damaged tissues. In addition, accumulating evidence indicates that MSC-derived exosomes play an important role, mainly by carrying a variety of bioactive substances that affect recipient cells. The potential mechanism by which MSC-derived exosomes mediate the effects of MSCs on ferroptosis has been previously demonstrated. This review provides the first overview of the current knowledge on ferroptosis, MSCs, and MSC-derived exosomes and highlights the potential application of MSCs exosomes in the treatment of ferroptotic conditions. It summarizes their mechanisms of action and techniques for enhancing MSC functionality. Results obtained from a large number of experimental studies revealed that both local and systemic administration of MSCs effectively suppressed ferroptosis in injured hepatocytes, neurons, cardiomyocytes, and nucleus pulposus cells and promoted the survival and regeneration of injured organs.

Methods

We reviewed the role of ferroptosis in related tissues and organs, focusing on its characteristics in different diseases. Additionally, the effects of MSCs and MSC-derived exosomes on ferroptosis-related pathways in various organs were reviewed, and the mechanism of action was elucidated. MSCs were shown to improve the disease course by regulating ferroptosis.

A Dual Role of Mesenchymal Stem Cell Derived Small Extracellular Vesicles on TRPC6 Protein and Mitochondria to Promote Diabetic Wound Healing

Diabetic wounds exhibit delayed and incomplete healing, usually due to vascular and nerve damage. Dysregulation of cellular Ca2+ homeostasis has recently been shown to be closely related to insulin resistance and type 2 diabetes mellitus. However, the involvement of this dysregulation in diabetic wound complications remains unknown. In this study, we found calcium dysregulation in patients with diabetic ulcers via tissue protein profiling. High glucose and glucometabolic toxicant stimulation considerably impaired the function of TRPC6, a pore subunit of transient receptor potential channels mediating Ca2+ influx, and mitochondria, which regulate calcium cycling and metabolism. Furthermore, we found that mesenchymal stem cell (MSC)-derived small extracellular vesicles (MSC-sEVs) could play a dual role in restoring the function of TRPC6 and mitochondria by delivering transcription factor SP2 and deubiquitinating enzyme USP9, respectively. MSC-sEVs could transfer SP2 that activated TRPC6 expression by binding to its specific promoter regions (-1519 to -1725 bp), thus recovering Ca2+ influx and downstream pathways. MSC-sEVs also promoted mitophagy to restore mitochondrial function by transporting USP9 that stabilized the expression of Parkin, a major player in mitophagy, thereby guaranteeing Ca2+ efflux and avoidance of Ca2+ overload. Targeting the regulation of calcium homeostasis provides a perspective for understanding diabetic wound healing, and the corresponding design of MSC-sEVs could be a potential therapeutic strategy.

Exogenous chelating agents influence growth, physiological characteristics and cell ultrastructure of Robinia pseudoacacia seedlings under lead-cadmium stress

Heavy metal pollution of soil, especially by lead (Pb) and cadmium (Cd), is a serious problem worldwide. The application of safe chelating agents, combined with the growing of tolerant trees, constitutes an approach for phytoremediation of heavy-metal-contaminated soil. This study aimed to determine whether the two safe chelators, tetrasodium glutamate diacetate (GLDA) and citric acid (CA), could improve the phytoremediation capacity of black locust (Robinia pseudoacacia L.) in a Pb-Cd-contaminated soil and to find the key factors affecting the biomass accumulation of stressed black locust. In Pb- and Cd-stressed black locust plants, medium- and high-concentration GLDA treatment inhibited the growth, chlorophyll synthesis and maximum photochemical efficiency (Fv/Fm), promoted the absorption of Pb and Cd ions and resulted in the shrinkage of chloroplasts and starch grains when compared with those in Pb- and Cd-stressed plants that were not treated with GLDA. The effects of CA on plant growth, ion absorption, chlorophyll content, chlorophyll fluorescence and organelle size were significantly weaker than those of GLDA. The effect of both agents on Cd absorption was greater than that on Pb absorption in all treatments. The levels of chlorophyll a and plant tissue Cd and rates of starch metabolism were identified as the key factors affecting plant biomass accumulation in GLDA and CA treatments. In the future, GLDA can be combined with functional bacteria and/or growth promoters to promote the growth of Pb- and Cd-stressed plants and to further improve the soil restoration efficiency following pollution by heavy metals. Application of CA combined with the growing of black locust plants has great potential for restoring the Cd-polluted soil. These findings also provide insights into the practical use of GLDA and CA in phytoremediation by R. pseudoacacia and the tolerant mechanisms of R. pseudoacacia to Pb-Cd-contaminated soil.

Exosomes and exosome composite scaffolds in periodontal tissue engineering

Promoting complete periodontal regeneration of damaged periodontal tissues, including dental cementum, periodontal ligament, and alveolar bone, is one of the challenges in the treatment of periodontitis. Therefore, it is urgent to explore new treatment strategies for periodontitis. Exosomes generated from stem cells are now a promising alternative to stem cell therapy, with therapeutic results comparable to those of their blast cells. It has great potential in regulating immune function, inflammation, microbiota, and tissue regeneration and has shown good effects in periodontal tissue regeneration. In addition, periodontal tissue engineering combines exosomes with biomaterial scaffolds to maximize the therapeutic advantages of exosomes. Therefore, this article reviews the progress, challenges, and prospects of exosome and exosome-loaded composite scaffolds in periodontal regeneration.

Mesenchymal stem cell-derived exosomes as delivery vehicles for non-coding RNAs in lung diseases

The burden of lung diseases is gradually increasing with an increase in the average human life expectancy. Therefore, it is necessary to identify effective methods to treat lung diseases and reduce their social burden. Currently, an increasing number of studies focus on the role of mesenchymal stem cell-derived exosomes (MSC-Exos) as a cell-free therapy in lung diseases. They show great potential for application to lung diseases as a more stable and safer option than traditional cell therapies. MSC-Exos are rich in various substances, including proteins, nucleic acids, and DNA. Delivery of Non-coding RNAs (ncRNAs) enables MSC-Exos to communicate with target cells. MSC-Exos significantly inhibit inflammatory factors, reduce oxidative stress, promote normal lung cell proliferation, and reduce apoptosis by delivering ncRNAs. Moreover, MSC-Exos carrying specific ncRNAs affect the proliferation, invasion, and migration of lung cancer cells, thereby playing a role in managing lung cancer. The detailed mechanisms of MSC-Exos in the clinical treatment of lung disease were explored by developing standardized culture, isolation, purification, and administration strategies. In summary, MSC-Exo-based delivery methods have important application prospects for treating lung diseases.

Adipose Mesenchymal Stem Cell-derived Exosomes Enhanced Glycolysis through the SIX1/HBO1 Pathway against Oxygen and Glucose Deprivation Injury in Human Umbilical Vein Endothelial Cells

BACKGROUND

Angiogenesis and energy metabolism mediated by adipose mesenchymal stem cell-derived exosomes (AMSC-exos) are promising therapeutics for vascular diseases.

OBJECTIVES

The current study aimed to explore whether AMSC-exos have therapeutic effects on oxygen and glucose deprivation (OGD) human umbilical vein endothelial cells (HUVECs) injury by modulating the SIX1/HBO1 signaling pathway to upregulate endothelial cells (E.C.s) glycolysis and angiogenesis.

METHODS

AMSC-exos were isolated and characterized following standard protocols. AMSC-exos cytoprotective effects were evaluated in the HUVECs-OGD model. The proliferation, migration, and tube formation abilities of HUVECs were assessed. The glycolysis level was evaluated by detecting lactate production and ATP synthesis. The expressions of HK2, PKM2, VEGF, HIF-1α, SIX1, and HBO1 were determined by western blotting, and finally, the SIX1 overexpression vector or small interfering RNA (siRNA) was transfected into HUVECs to assess the change in HBO1 expression.

RESULTS

Our study revealed that AMSC-exos promotes E.C.s survival after OGD, reducing E.C.s apoptosis while strengthening E.C.'s angiogenic ability. AMSC-exos enhanced glycolysis and reduced OGD-induced ECs injury by modulation of the SIX1/HBO1 signaling pathway, which is a novel anti-endothelial cell injury role of AMSC-exos that regulates glycolysis via activating the SIX1/HBO1 signaling pathway.

CONCLUSION

The current study findings demonstrate a useful angiogenic therapeutic strategy for AMSC-exos treatment in vascular injury, thus providing new therapeutic ideas for treating ischaemic diseases.

Size matters: Functional differences of small extracellular vesicle subpopulations in cardiac repair responses

Cardiac progenitor cell (CPC)-derived small extracellular vesicles (sEVs) exhibit great potential to stimulate cardiac repair. However, the multifaceted nature of sEV heterogeneity presents a challenge in understanding the distinct mechanisms underlying their regenerative abilities. Here, a dual-step multimodal flowthrough and size-exclusion chromatography method was applied to isolate and separate CPC-derived sEV subpopulations to study the functional differences related to cardiac repair responses. Three distinct sEV subpopulations were identified with unique protein profiles. Functional cell assays for cardiac repair-related processes demonstrated that the middle-sized and smallest-sized sEV subpopulations exhibited the highest pro-angiogenic and anti-fibrotic activities. Proteasome activity was uniquely seen in the smallest-sized subpopulation. The largest-sized subpopulation showed no effect in any of the functional assays. This research uncovers the existence of sEV subpopulations, each characterized by a distinct composition and biological function. Enhancing our understanding of sEV heterogeneity will provide valuable insights into sEV mechanisms of action, ultimately accelerating the translation of sEV therapeutics.

Secretome Analysis: Reading Cellular Sign Language to Understand Intercellular Communication

A significant portion of mammalian proteomes is secreted to the extracellular space to fulfill crucial roles in cell-to-cell communication. To best recapitulate the intricate and multi-faceted crosstalk between cells in a live organism, there is an ever-increasing need for methods to study protein secretion in model systems that include multiple cell types. In addition, posttranslational modifications further expand the complexity and versatility of cellular communication. This review aims to summarize recent strategies and model systems that employ cellular coculture, chemical biology tools, protein enrichment, and proteomic methods to characterize the composition and function of cellular secretomes. This is all geared towards gaining better understanding of organismal biology in vivo mediated by secretory signaling.

Diabetic state of human coronary artery endothelial cells results in altered effects of bone mesenchymal stem cell-derived extracellular vesicles

Human bone mesenchymal stem cell-derived extracellular vesicles (HBMSC-EV) have been used successfully in animal models of myocardial ischemia, yet have dampened effects in metabolic syndrome through unknown mechanisms. This study demonstrates the basal differences between non-diabetic human coronary artery endothelial cells (HCAEC) and diabetic HCAEC (DM-HCAEC), and how these cells respond to the treatment of HBMSC-EV. HCAEC and DM-HCAEC were treated with HBMSC-EV for 6 h. Proteomics, western blot analysis, and tube formation assays were performed. Key metabolic, growth, and stress/starvation cellular responses were significantly altered in DM-HCAEC in comparison to that of HCAEC at baseline. Proteomics demonstrated increased phosphorus metabolic process and immune pathways and decreased RNA processing and biosynthetic pathways in DM-HCAEC. Similar to previous in vivo findings, HCAEC responded to the HBMSC-EV with regenerative and anti-inflammatory effects through the upregulation of multiple RNA pathways and downregulation of immune cell activation pathways. In contrast, DM-HCAEC had a significantly diminished response to HBMSC-EV, likely due to the baseline abnormalities in DM-HCAEC. To achieve the full benefits of HBMSC-EV and for a successful transition of this potential therapeutic agent to clinical studies, the abnormalities found in DM-HCAEC will need to be further studied.

Natural self-healing injectable hydrogels loaded with exosomes and berberine for infected wound healing

Complete and rapid healing of infected skin wounds remains a challenge in current clinical treatment. In this study, we prepared a self-healing injectable CK hydrogel by crosslinking two natural polysaccharides, carboxymethyl chitosan and oxidized konjac glucomannan, based on the Schiff base bond. To enhance the biological function of the hydrogel, we multi-functionalized hydrogen by loading it with berberine (BBR) and stem cell-derived exosomes (Exo), forming a composite hydrogel, CK@BBR&Exo, which could be injected directly into the wound through a needle and adhered to the wound. Furthermore, the self-healing properties of CK@BBR&Exo increased its usefulness and service life. Additionally, the drug-loaded CK@BBR&Exo hydrogel was versatile, inhibiting bacterial growth, regulating the inflammatory response, and promoting neovascularization in infected skin wounds, thus achieving the rapid healing of infected skin wounds. These results suggest that the CK@BBR&Exo-injectable self-healing hydrogel is an ideal dressing for treating infected skin wounds.

Exosomal miR-218 derived from mesenchymal stem cells inhibits endothelial-to-mesenchymal transition by epigenetically modulating of BMP2 in pulmonary fibrosis

Endothelial-to-mesenchymal transition (EndMT), the process by which endothelial cells lose their characteristics and acquire mesenchymal phenotypes, participates in the pathogenic mechanism of idiopathic pulmonary fibrosis. Recently, exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-Exos) has been introduced as a promising treatment in organ fibrosis. This study aimed to explore the effects as well as the molecular mechanism for hucMSC-Exo in pulmonary fibrosis. The intravenous administration of hucMSC-Exos alleviated bleomycin-induced pulmonary fibrosis in vivo. Moreover, hucMSC-Exos elevated miR-218 expression and restored endothelial properties weakened by TGF-β in endothelial cells. Knockdown of miR-218 partially abrogated the inhibition effect of hucMSC-Exos on EndMT. Our mechanistic study further demonstrated that MeCP2 was the direct target of miR-218. Overexpressing MeCP2 aggravated EndMT and caused increased CpG islands methylation at BMP2 promoter, which lead to BMP2 post-transcriptional gene silence. Transfection of miR-218 mimic increased BMP2 expression as well, which was downregulated by overexpression of MeCP2. Taken together, these findings indicate exosomal miR-218 derived from hucMSCs may possess anti-fibrotic properties and inhibit EndMT through MeCP2/BMP2 pathway, providing a new avenue of preventive application in pulmonary fibrosis.

Recent engineering advances of EVs for compounds, nucleic acids, and TCM delivery

Extracellular vesicles (EVs) are phospholipid bilayer nano-vesicles that were originally identified to deliver signals for intercellular communications. Based on the dynamic contents including proteins, nucleic acids and metabolites, EVs have been developed into diagnostic and therapeutic fields including cardiovascular diseases, neurological disorders and infectious diseases. A growing number of investigations revealed that EVs are also powerful carriers of loaded compounds and nucleic acids as enhanced treatments. Herein, we summarized the recent engineering advances related to three major issues when applying EVs in drug delivery systems: EVs isolation, drug loading strategies and targeting delivery approaches. Moreover, current applications of traditional Chinese medicine (TCM), in composition or compound form, are searched and listed as unique combinations with EVs. Further, we discuss emerging challenges and consider future directions of drug-loading EVs in therapeutic opportunities. This review discusses pros and cons of collecting, drug loading and delivery strategies of EVs as delivery systems, and highlights the promising combination with traditional Chinese medicine to help us advance its clinical application.

Intravenous injection of tumor extracellular vesicles suppresses tumor growth by reducing the regulatory T cell phenotype

BACKGROUND

Colorectal cancer is a disease of unmet medical need. Although extracellular vesicles (EVs) have been implicated in anti-tumor responses, discrepancies were observed among studies. We analyzed the role of tumor-derived EVs (TEVs) in tumor progression in vivo by focusing on regulatory T (Treg) cells, which play essential roles in tumor development and progression.

METHODS

A mouse model of colorectal cancer lung metastasis was generated using BALB/c mice by tail vein injection of the BALB/c colon adenocarcinoma cell line Colon-26. TEVs derived from Colon-26 and BALB/c lung squamous cell carcinoma ASB-XIV were retrieved from the culture media supernatants. A TEV equivalent to 10 µg protein was injected every other day for 2 weeks.

RESULTS

Histology and immunohistochemistry studies revealed that lung tumors reduced in the Colon-26-EV group when compared to the phosphate-buffered saline (PBS) group. The population of CD4 + FoxP3 + cells in the lung was upregulated in the PBS group mice when compared to the healthy mice (P < 0.001), but was significantly downregulated in the Colon-26-EV group mice when compared to the PBS group mice (P < 0.01). Programmed cell death protein 1, glucocorticoid-induced TNFR-related protein, and CD69 expression in lung Treg cells were markedly upregulated in the PBS group when compared to the healthy mice, but downregulated in the Colon-26-EV group when compared to the PBS group. The changes in expression were dose-dependent for Colon-26-EVs. ASB-EVs also led to significantly downregulated Treg cell expression, although non-cancer line 3T3-derived EVs did not.

CONCLUSION

Our study suggests that TEVs possess components for tumor suppression.

Research progress of odontogenic extracellular vesicles in regeneration of dental pulp

It is well understood that maintaining viable pulp is critical for tooth retention. This review focused on cell-free therapy based on extracellular vesicles (EVs), a novel minimally invasive treatment strategy for endodontic restoration. This study was conducted by searching mainstream electronic databases such as Web of Science and PubMed for relevant studies on the therapeutic role of odontogenic EVs in pulp healing published in the last five years. We selected 89 relevant articles and discovered that dental stem cells (DSCs) derived EVs (DSC-EVs) have become a research hotspot in oral regenerative medicine, with significant advantages over cell transplantation in terms of low immunogenicity, ease of isolation, preservation, and management. Here, we introduce in detail the therapeutic effects of DSC-EVs for pulp restoration from three perspectives: excellent odontogenic properties, clinical applications, and possible molecular mechanisms. This article contributes a new viewpoint to the field of regenerative endodontics.

Extracellular Vesicle Heterogeneity and Its Impact for Regenerative Medicine Applications

Extracellular vesicles (EVs) are cell-derived membrane-enclosed particles that are involved in physiologic and pathologic processes. EVs are increasingly being studied for therapeutic applications in the field of regenerative medicine. Therapeutic application of stem cell-derived EVs has shown great potential to stimulate tissue repair. However, the exact mechanisms through which they induce this effect have not been fully clarified. This may to a large extent be attributed to a lack of knowledge on EV heterogeneity. Recent studies suggest that EVs represent a heterogeneous population of vesicles with distinct functions. The heterogeneity of EVs can be attributed to differences in their biogenesis, and as such, they can be classified into distinct populations that can then be further subcategorized into various subpopulations. A better understanding of EV heterogeneity is crucial for elucidating their mechanisms of action in tissue regeneration. This review provides an overview of the latest insights on EV heterogeneity related to tissue repair, including the different characteristics that contribute to such heterogeneity and the functional differences among EV subtypes. It also sheds light on the challenges that hinder clinical translation of EVs. Additionally, innovative EV isolation techniques for studying EV heterogeneity are discussed. Improved knowledge of active EV subtypes would promote the development of tailored EV therapies and aid researchers in the translation of EV-based therapeutics to the clinic. SIGNIFICANCE STATEMENT: Within this review we discuss the differences in regenerative properties of extracellular vesicle (EV) subpopulations and implications of EV heterogeneity for development of EV-based therapeutics. We aim to provide new insights into which aspects are leading to heterogeneity in EV preparations and stress the importance of EV heterogeneity studies for clinical applications.

Mesenchymal stem cell-derived extracellular vesicles in skin wound healing: roles, opportunities and challenges

Skin wounds are characterized by injury to the skin due to trauma, tearing, cuts, or contusions. As such injuries are common to all human groups, they may at times represent a serious socioeconomic burden. Currently, increasing numbers of studies have focused on the role of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in skin wound repair. As a cell-free therapy, MSC-derived EVs have shown significant application potential in the field of wound repair as a more stable and safer option than conventional cell therapy. Treatment based on MSC-derived EVs can significantly promote the repair of damaged substructures, including the regeneration of vessels, nerves, and hair follicles. In addition, MSC-derived EVs can inhibit scar formation by affecting angiogenesis-related and antifibrotic pathways in promoting macrophage polarization, wound angiogenesis, cell proliferation, and cell migration, and by inhibiting excessive extracellular matrix production. Additionally, these structures can serve as a scaffold for components used in wound repair, and they can be developed into bioengineered EVs to support trauma repair. Through the formulation of standardized culture, isolation, purification, and drug delivery strategies, exploration of the detailed mechanism of EVs will allow them to be used as clinical treatments for wound repair. In conclusion, MSC-derived EVs-based therapies have important application prospects in wound repair. Here we provide a comprehensive overview of their current status, application potential, and associated drawbacks.

Extracellular vesicles and nanoparticles: emerging complexities

The study of extracellular vesicles (EVs) and nanoparticles (NPs) is rapidly expanding because recent discoveries have revealed a much greater complexity and diversity than was appreciated only a few years ago. New types of EVs and NPs have recently been described. Proteins and nucleic acids previously thought to be packaged in exosomes appear to be more enriched in different types of EVs and in two recently identified amembranous NPs, exomeres and supermeres. Thus, our understanding of the cell biology and intercellular communication facilitated by the release of EVs and NPs is in a state of flux. In this review, we describe the different types of EVs and NPs, highlight recent advances, and present major outstanding questions.

Cardiac progenitor cell-derived extracellular vesicles promote angiogenesis through both associated- and co-isolated proteins

Extracellular vesicles (EVs) are cell-derived lipid bilayer-enclosed particles that play a role in intercellular communication. Cardiac progenitor cell (CPC)-derived EVs have been shown to protect the myocardium against ischemia-reperfusion injury via pro-angiogenic effects. However, the mechanisms underlying CPC-EV-induced angiogenesis remain elusive. Here, we discovered that the ability of CPC-EVs to induce in vitro angiogenesis and to stimulate pro-survival pathways was lost upon EV donor cell exposure to calcium ionophore. Proteomic comparison of active and non-active EV preparations together with phosphoproteomic analysis of activated endothelial cells identified the contribution of candidate protein PAPP-A and the IGF-R signaling pathway in EV-mediated cell activation, which was further validated using in vitro angiogenesis assays. Upon further purification using iodixanol gradient ultracentrifugation, EVs partly lost their activity, suggesting a co-stimulatory role of co-isolated proteins in recipient cell activation. Our increased understanding of the mechanisms of CPC-EV-mediated cell activation will pave the way to more efficient EV-based therapeutics.

Advances in Immunomodulatory Mechanisms of Mesenchymal Stem Cells-Derived Exosome on Immune Cells in Scar Formation

Pathological scars are the result of over-repair and excessive tissue proliferation of the skin injury. It may cause serious dysfunction, resulting in psychological and physiological burdens on the patients. Currently, mesenchymal stem cells-derived exosomes (MSC-Exo) displayed a promising therapeutic effect on wound repair and scar attenuation. But the regulatory mechanisms are opinions vary. In view of inflammation has long been proven as the initial factor of wound healing and scarring, and the unique immunomodulation mechanism of MSC-Exo, the utilization of MSC-Exo may be promising therapeutic for pathological scars. However, different immune cells function differently during wound repair and scar formation. The immunoregulatory mechanism of MSC-Exo would differ among different immune cells and molecules. Herein, this review gave a comprehensive summary of MSC-Exo immunomodulating different immune cells in wound healing and scar formation to provide basic theoretical references and therapeutic exploration of inflammatory wound healing and pathological scars.

Extracellular vesicle-based biovectors in chronic wound healing: Biogenesis and delivery approaches

Chronic wounds remain an unresolved medical issue because of major social and therapeutic repercussions that require extensive focus. Recent related theragnostic focuses only on wound management and is not effectively promoting chronic wound healing. The rising number of patients with either under-healing or over-healing wounds highlights the ineffectiveness of current wound-healing treatments, and thus, there is an unmet need to focus on alternative treatments. To cover this gap, extracellular vesicles (EVs), for targeted delivery of therapeutics, are emerging as a potential therapy to treat both acute and persistent wounds. To address these issues, we explore the core biology of EVs, associated pharmacology, comprehension of immunogenic outcomes, and potential for long-term wound treatment with improved effectiveness and their nonacceptable side effects. Additionally, the therapeutic role of EVs in severe wound infections through biogenetic moderation, in combination with biomaterials (functional in nature), as well as drug carriers that can offer opportunities for the development of new treatments for this long-term condition, are also carefully elaborated, with an emphasis on biomaterial-based drug delivery systems. It is observed that exploring difficulties and potential outcomes of clinical translation of EV-based therapeutics for wound management has the potential to be adopted as a future therapy.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

Comprehensive isolation of extracellular vesicles and nanoparticles

There is an increasing appreciation for the heterogeneous nature of extracellular vesicles (EVs). In addition, two nonvesicular extracellular nanoparticles (NVEPs), exomeres and supermeres, have been discovered recently that are enriched in many cargo previously ascribed to EVs. The EV field has largely focused on EV isolation and characterization, while studies on NVEPs are limited. At this juncture, it is critically important to have robust and reliable methods to separate distinct populations of EVs and NVEPs to assign cargo to their correct carrier. Here, we provide a comprehensive step-by-step protocol for sequential isolation of large and small EVs, nonvesicular fractions, exomeres and supermeres from the same starting material. We describe in detail the use of differential ultracentrifugation, filtration, concentration and high-resolution density-gradient fractionation to obtain purified fractions of distinct populations of EVs and NVEPs. This protocol allows assignment and enrichment of a biomolecule of interest to its specific extracellular compartment. Compared to other isolation methods, our protocol has unique advantages, including high purity and reproducibility, with minimal expertise required. The protocol can be applied to purification of EVs and NVEPs from cell culture medium and human plasma and requires ~72 h to complete. Adoption of this protocol will help translational investigators identify potential circulating biomarkers and therapeutic targets for a host of human diseases and allow basic scientists to better understand EV and NVEP biogenesis and function. Overall, this protocol will allow those interested in isolating EVs and extracellular particles to advance scientific inquiry to answer outstanding questions in the field.

The Role of non-muscle actin paralogs in cell cycle progression and proliferation

Uncontrolled cell proliferation leads to several pathologies, including cancer. Thus, this process must be tightly regulated. The cell cycle accounts for cell proliferation, and its progression is coordinated with changes in cell shape, for which cytoskeleton reorganization is responsible. Rearrangement of the cytoskeleton allows for its participation in the precise division of genetic material and cytokinesis. One of the main cytoskeletal components is filamentous actin-based structures. Mammalian cells have at least six actin paralogs, four of which are muscle-specific, while two, named β- and γ-actin, are abundantly present in all types of cells. This review summarizes the findings that establish the role of non-muscle actin paralogs in regulating cell cycle progression and proliferation. We discuss studies showing that the level of a given non-muscle actin paralog in a cell influences the cell's ability to progress through the cell cycle and, thus, proliferation. Moreover, we elaborate on the non-muscle actins' role in regulating gene transcription, interactions of actin paralogs with proteins involved in controlling cell proliferation, and the contribution of non-muscle actins to different structures in a dividing cell. The data cited in this review show that non-muscle actins regulate the cell cycle and proliferation through varying mechanisms. We point to the need for further studies addressing these mechanisms.

Dauer larva-derived extracellular vesicles extend the life of Caenorhabditis elegans

There is growing evidence that extracellular vesicles (EVs) play a functional role in tissue repair and anti-aging by transferring the contents of donor cells to recipient cells. We hypothesized that Dauer (C. elegans), known as "ageless" nematodes, can also secrete extracellular vesicles and influence the lifespan of C. elegans. Here, we isolated EVs of dauer larvae (dauer EVs). Dauer EVs were characterized using transmission electron microscopy, nanoparticle tracking analysis (NTA), and Western blot analysis. Wild-type C. elegans were fed in the presence or absence of dauer EVs and tested for a range of phenotypes, including longevity, mobility and reproductive capacity. Results showed that dauer EVs increased the average lifespan of nematodes by 15.74%, improved mobility, slowed age-related pigmentation as well as body length, and reduced the accumulation of reactive oxygen species and lipids, while not impairing nematode reproductive capacity. These findings suggest that dauer EVs can extend the lifespan of C. elegans as well as the healthy lifespan by reducing ROS accumulation, with potential anti-aging capacity.

Dapagliflozin-Loaded Exosome Mimetics Facilitate Diabetic Wound Healing by HIF-1α-Mediated Enhancement of Angiogenesis

Angiogenesis plays a critical role in diabetic wound healing. However, no effective strategies have been developed to target endothelial cells (ECs) to facilitate diabetic wound healing. Dapagliflozin (DA) as a sodium-glucose linked transporter 2 (SGLT2) inhibitor, may promote neovascularization in diabetic mice via HIF-1α-mediated enhancement of angiogenesis. Here, the bioinspired nanovesicles (NVs) prepared from induced pluripotent stem cells-derived ECs through an extrusion approach are reported, which can function as exosome mimetics to achieve targeted deliver of DA. Abundant membrane C-X-C motif chemokine receptor 4 conferred the EC-targeting ability of these NVs and the endothelial homology facilitated the accumulation in ECs. Furthermore, these DA-loaded induced pluripotent stem cells (iPSC)-EC NVs can facilitate angiogenesis and diabetic wound healing by HIF-1α/VEGFA pathway. Taken together, this study indicated that targeting ECs and regulating angiogenesis may be a promising strategy for the treatment of diabetic wound healing.

Tuning the Extracellular Vesicles Membrane through Fusion for Biomedical Applications

Membrane fusion is one of the key phenomena in the living cell for maintaining the basic function of life. Extracellular vesicles (EVs) have the ability to transfer information between cells through plasma membrane fusion, making them a promising tool in diagnostics and therapeutics. This study explores the potential applications of natural membrane vesicles, EVs, and their fusion with liposomes, EVs, and cells and introduces methodologies for enhancing the fusion process. EVs have a high loading capacity, bio-compatibility, and stability, making them ideal for producing effective drugs and diagnostics. The unique properties of fused EVs and the crucial design and development procedures that are necessary to realize their potential as drug carriers and diagnostic tools are also examined. The promise of EVs in various stages of disease management highlights their potential role in future healthcare.

Current challenges and future directions for engineering extracellular vesicles for heart, lung, blood and sleep diseases

Extracellular vesicles (EVs) carry diverse bioactive components including nucleic acids, proteins, lipids and metabolites that play versatile roles in intercellular and interorgan communication. The capability to modulate their stability, tissue-specific targeting and cargo render EVs as promising nanotherapeutics for treating heart, lung, blood and sleep (HLBS) diseases. However, current limitations in large-scale manufacturing of therapeutic-grade EVs, and knowledge gaps in EV biogenesis and heterogeneity pose significant challenges in their clinical application as diagnostics or therapeutics for HLBS diseases. To address these challenges, a strategic workshop with multidisciplinary experts in EV biology and U.S. Food and Drug Administration (USFDA) officials was convened by the National Heart, Lung and Blood Institute. The presentations and discussions were focused on summarizing the current state of science and technology for engineering therapeutic EVs for HLBS diseases, identifying critical knowledge gaps and regulatory challenges and suggesting potential solutions to promulgate translation of therapeutic EVs to the clinic. Benchmarks to meet the critical quality attributes set by the USFDA for other cell-based therapeutics were discussed. Development of novel strategies and approaches for scaling-up EV production and the quality control/quality analysis (QC/QA) of EV-based therapeutics were recognized as the necessary milestones for future investigations.

Single-cell transcriptomics reveal extracellular vesicles secretion with a cardiomyocyte proteostasis signature during pathological remodeling

Aberrant Wnt activation has been reported in failing cardiomyocytes. Here we present single cell transcriptome profiling of hearts with inducible cardiomyocyte-specific Wnt activation (β-catΔex3) as well as with compensatory and failing hypertrophic remodeling. We show that functional enrichment analysis points to an involvement of extracellular vesicles (EVs) related processes in hearts of β-catΔex3 mice. A proteomic analysis of in vivo cardiac derived EVs from β-catΔex3 hearts has identified differentially enriched proteins involving 20 S proteasome constitutes, protein quality control (PQC), chaperones and associated cardiac proteins including α-Crystallin B (CRYAB) and sarcomeric components. The hypertrophic model confirms that cardiomyocytes reacted with an acute early transcriptional upregulation of exosome biogenesis processes and chaperones transcripts including CRYAB, which is ameliorated in advanced remodeling. Finally, human induced pluripotent stem cells (iPSC)-derived cardiomyocytes subjected to pharmacological Wnt activation recapitulated the increased expression of exosomal markers, CRYAB accumulation and increased PQC signaling. These findings reveal that secretion of EVs with a proteostasis signature contributes to early patho-physiological adaptation of cardiomyocytes, which may serve as a read-out of disease progression and can be used for monitoring cellular remodeling in vivo with a possible diagnostic and prognostic role in the future.

The therapeutic and commercial landscape of stem cell vesicles in regenerative dermatology

Extracellular vesicles (EVs) are lipid enveloped nanoparticles that are naturally produced by cells and function in the intercellular transfer of biological material such as proteins, RNAs and metabolites. They have been shown to act in an autocrine and paracrine manner to alter the functions of local and distant recipient cells, with a growing body of evidence highlighting their wide-ranging functions in regenerative processes such as stem cell maintenance, tissue repair and immune modulation. EVs offer several potential advantages over stem cell therapies such as improved safety profiles, scalability, and enhanced storage and quality control of the final product. In fact, many of the pro-regenerative outcomes of stem cell therapies have been attributed to the release of mesenchymal stem cell-derived EVs (MSC-EVs) and their potent effects on extracellular matrix turnover, local cell recruitment, proliferation and angiogenesis is now well described. These positive outcomes have led to clinical trials assessing the safety of MSC-EVs for applications in wound healing and the treatment of cutaneous ulcers, as well as the emergence of multiple commercial MSC-EV sources marketed for topical application in cosmetic medicine. However, regenerative EV therapeutics remain in their infancy and pertinent questions regarding product standardisation, potency and the regulatory landscape surrounding the development of these promising nano-therapeutics must be addressed to ensure safe and effective clinical adoption. In this article we provide an overview of the emerging landscape of MSC-EVs in regenerative dermatology and cosmetic science, highlighting the underlying biological mechanisms pertinent to their application and providing a perspective on current safety considerations, regulation and future directions in the field.

Establishing an hTERT-driven immortalized umbilical cord-derived mesenchymal stem cell line and its therapeutic application in mice with liver failure

Acute liver failure (ALF) is characterized by rapid liver cell destruction. It is a multi-etiological and fulminant complication with a clinical mortality of over 80%. Therapy using mesenchymal stem cells (MSCs) or MSCs-derived exosomes can alleviate acute liver injury, which has been demonstrated in animal experiments and clinical application. However, similar to other stem cells, different cell sources, poor stability, cell senescence and other factors limit the clinical application of MSCs. To achieve mass production and quality control on stem cells and their exosomes, transfecting umbilical cord mesenchymal stem cell (UCMSC) with lentivirus overexpressing human telomerase reverse transcriptase (hTERT) gene, the hTERT-UCMSC was constructed as an immortalized MSC cell line. Compared with the primary UCMSC (P3) and immortalized cell line hTERT-UCMSC at early passage (P10), the hTERT-UCMSC retained the key morphological and physiological characteristics of UCMSC at the 35th passage (P35), and showed no signs of carcinogenicity and toxic effect in mice. There was no difference in either exosome production or characteristics of exosomes among cultures from P3 primary cells, P10 and P35 immortalized hTERT-UCMSCs. Inoculation of either hTERT-UCMSC (P35) or its exosomes improved the survival rate and liver function of ALF mice induced by thioacetamide (TAA). Our findings suggest that this immortalized cell line can maintain its characteristics in long-term culture. Inoculation of hTERT-UCMSC and its exosomes could potentially be used in clinics for the treatment of liver failure in the future.

Improving extracellular vesicles production through a Bayesian optimization-based experimental design

With the growing demand and diversity of biological drugs, developing optimal processes for their accelerated production with minimal resource utilization is a pressing challenge. Typically, such optimization involves multiple target properties, such as production yield, biological activity, and product purity. Therefore, strategic experimental design techniques that can characterize the parameter space while simultaneously arriving at the optimal process satisfying multiple target properties are required. To achieve this, we propose the use of a multi-objective batch Bayesian optimization (MOBBO) algorithm and illustrate its successful application for the production of extracellular vesicles (EVs) from a 3D culture of mesenchymal stem cells (MSCs) considering three objectives, namely to maximize the vesicle-to-protein ratio, maximize the enzymatic activity of the MSC-EV protein CD73, and minimize the amount of calregulin impurities. We show that the optimal combination of the process parameters to address the intended objectives could be achieved with only 32 experiments. For the four parameters considered (i.e., microcarrier concentration, seeding density, centrifugation time, and impeller speed), this number of experiments is comparable to or lower than the classical design of experiments (DoE) and the traditional one-factor-at-a-time (OFAT) approach. We illustrate how the algorithm adaptively samples in the process parameter space, selectively excluding unfavorable regions, thus minimizing the number of experiments required to reach optimal conditions. Finally, we compare the obtained solutions to the literature data and present possible applications of the collected data for other modeling activities such as Quality by Design, process monitoring, control, and scale-up.

Extracellular Vesicles as Drug Targets and Delivery Vehicles for Cancer Therapy

Extracellular vesicles (EVs) are particles that are released from cells into the extracellular space both under pathological and normal conditions. It is now well established that cancer cells secrete more EVs compared to non-cancerous cells and that, captivatingly, several proteins that are involved in EV biogenesis and secretion are upregulated in various tumours. Recent studies have revealed that EVs facilitate the interaction between cancer cells and their microenvironment and play a substantial role in the growth of tumours. As EVs are involved in several aspects of cancer progression including angiogenesis, organotropism, pre-metastatic niche formation, fostering of metastasis, and chemoresistance, inhibiting the release of EVs from cancer and the surrounding tumour microenvironment cells has been proposed as an ideal strategy to treat cancer and associated paraneoplastic syndromes. Lately, EVs have shown immense benefits in preclinical settings as a novel drug delivery vehicle. This review provides a brief overview of the role of EVs in various hallmarks of cancer, focusing on (i) strategies to treat cancer by therapeutically targeting the release of tumour-derived EVs and (ii) EVs as valuable drug delivery vehicles. Furthermore, we also outline the drawbacks of the existing anti-cancer treatments and the future prospective of EV-based therapeutics.

Evaluation and manipulation of tissue and cellular distribution of cardiac progenitor cell-derived extracellular vesicles

Cardiac progenitor cell-derived extracellular vesicles (CPC-EVs) have been successfully applied via different delivery routes for treating post-myocardial infarction injury in several preclinical models. Hence, understanding the in vivo fate of CPC-EVs after systemic or local, i.e. myocardial, delivery is of utmost importance for the further therapeutic application of CPC-EVs in cardiac repair. Here, we studied the tissue- and cell distribution and retention of CPC-EVs after intramyocardial and intravenous injection in mice by employing different EV labeling and imaging techniques. In contrast to progenitor cells, CPC-EVs demonstrated no immediate flush-out from the heart upon intramyocardial injection and displayed limited distribution to other organs over time, as determined by near-infrared imaging in living animals. By employing CUBIC tissue clearing and light-sheet fluorescent microscopy, we observed CPC-EV migration in the interstitial space of the myocardium shortly after EV injection. Moreover, we demonstrated co-localization with cTnI and CD31-positive cells, suggesting their interaction with various cell types present in the heart. On the contrary, after intravenous injection, most EVs accumulated in the liver. To potentiate such a potential systemic cardiac delivery route, targeting the cardiac endothelium could provide openings for directed CPC-EV therapy. We therefore evaluated whether decorating EVs with targeting peptides (TPs) RGD-4C or CRPPR connected to Lamp2b could enhance EV delivery to endothelial cells. Expression of both TPs enhanced CPC-EV uptake under in vitro continuous flow, but did not affect uptake under static cell culture conditions. Together, these data demonstrate that the route of administration influences CPC-EV biodistribution pattern and suggest that specific TPs could be used to target CPC-EVs to the cardiac endothelium. These insights might lead to a better application of CPC-EV therapeutics in the heart.

Scalable Generation of Nanovesicles from Human-Induced Pluripotent Stem Cells for Cardiac Repair

Extracellular vesicles (EVs) from stem cells have shown significant therapeutic potential to repair injured cardiac tissues and regulate pathological fibrosis. However, scalable generation of stem cells and derived EVs for clinical utility remains a huge technical challenge. Here, we report a rapid size-based extrusion strategy to generate EV-like membranous nanovesicles (NVs) from easily sourced human iPSCs in large quantities (yield 900× natural EVs). NVs isolated using density-gradient separation (buoyant density 1.13 g/mL) are spherical in shape and morphologically intact and readily internalised by human cardiomyocytes, primary cardiac fibroblasts, and endothelial cells. NVs captured the dynamic proteome of parental cells and include pluripotency markers (LIN28A, OCT4) and regulators of cardiac repair processes, including tissue repair (GJA1, HSP20/27/70, HMGB1), wound healing (FLNA, MYH9, ACTC1, ILK), stress response/translation initiation (eIF2S1/S2/S3/B4), hypoxia response (HMOX2, HSP90, GNB1), and extracellular matrix organization (ITGA6, MFGE8, ITGB1). Functionally, NVs significantly promoted tubule formation of endothelial cells (angiogenesis) (p < 0.05) and survival of cardiomyocytes exposed to low oxygen conditions (hypoxia) (p < 0.0001), as well as attenuated TGF-β mediated activation of cardiac fibroblasts (p < 0.0001). Quantitative proteome profiling of target cell proteome following NV treatments revealed upregulation of angiogenic proteins (MFGE8, MYH10, VDAC2) in endothelial cells and pro-survival proteins (CNN2, THBS1, IGF2R) in cardiomyocytes. In contrast, NVs attenuated TGF-β-driven extracellular matrix remodelling capacity in cardiac fibroblasts (ACTN1, COL1A1/2/4A2/12A1, ITGA1/11, THBS1). This study presents a scalable approach to generating functional NVs for cardiac repair.

Exosomes as CNS Drug Delivery Tools and Their Applications

Central nervous system (CNS) diseases threaten the health of people all over the world. However, due to the structural and functional particularities of the brain and spinal cord, CNS-targeted drug development is rather challenging. Exosomes are small cellular vesicles with lipid bilayers that can be secreted by almost all cells and play important roles in intercellular communication. The advantages of low immunogenicity, the ability to cross the blood-brain barrier, and the flexibility of drug encapsulation make them stand out among CNS drug delivery tools. Herein, we reviewed the research on exosomes in CNS drug delivery over the past decade and outlined the impact of the drug loading mode, administration route, and engineered modification on CNS targeting. Finally, we highlighted the problems and prospects of exosomes as CNS drug delivery tools.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Accelerate Diabetic Wound Healing via Promoting M2 Macrophage Polarization, Angiogenesis, and Collagen Deposition

Some scholars have suggested that the clinical application of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exo) might represent a novel strategy to improve diabetic wound healing. However, the mechanisms underlying the effects of hucMSCs-exo on wound healing remain poorly understood. This study aimed to identify the mechanism of hucMSCs-exo in treating diabetic wounds. HucMSCs-exo were isolated from human umbilical cord mesenchymal stem cells (hucMSCs) and subcutaneously injected into full-thickness wounds in diabetic rats. Wound healing closure rates and histological analysis were performed. The levels of tumor necrosis factor-α (TNF-α), macrophage mannose receptor (MMR/CD206), platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry. The degree of collagen deposition was examined using Masson’s trichrome staining. Gross evaluation of wound healing was carried out from day 0 to 14 post-surgery, and the wound site was harvested for histology on days 3, 7, and 14 post-wounding. HucMSCs-exo transplantation increased diabetic wound healing. In vitro, hucMSCs-exo promoted the proliferation of human umbilical vein endothelial cells (HUVECs) and NIH-3T3 cells. In vivo, hucMSCs-exo reduced wound area and inflammatory infiltration and increased collagen fibers. In addition, wound tissues in the hucMSCs-exo group had higher CD206, CD31, and VEGF expressions and lower TNF-α levels than those in the control group on day 14. Our results demonstrated that hucMSCs-exo facilitated diabetic wound repair by inducing anti-inflammatory macrophages and promoting angiogenesis and collagen deposition.

Tailored Extracellular Vesicles: Novel Tool for Tissue Regeneration

Extracellular vesicles (EVs) play an essential part in multiple pathophysiological processes including tissue injury and regeneration because of their inherent characteristics of small size, low immunogenicity and toxicity, and capability of carrying a variety of bioactive molecules and mediating intercellular communication. Nevertheless, accumulating studies have shown that the application of EVs faces many challenges such as insufficient therapeutic efficacy, a lack of targeting capability, low yield, and rapid clearance from the body. It is known that EVs can be engineered, modified, and designed to encapsulate therapeutic cargos like proteins, peptides, nucleic acids, and drugs to improve their therapeutic efficacy. Targeted peptides, antibodies, aptamers, magnetic nanoparticles, and proteins are introduced to modify various cell-derived EVs for increasing targeting ability. In addition, extracellular vesicle mimetics (EMs) and self-assembly EV-mimicking nanocomplex are applied to improve production and simplify EV purification process. The combination of EVs with biomaterials like hydrogel, and scaffolds dressing endows EVs with long-term therapeutic efficacy and synergistically enhanced regenerative outcome. Thus, we will summarize recent developments of EV modification strategies for more extraordinary regenerative effect in various tissue injury repair. Subsequently, opportunities and challenges of promoting the clinical application of engineered EVs will be discussed.

Mesenchymal stem cells exert renoprotection via extracellular vesicle-mediated modulation of M2 macrophages and spleen-kidney network

Adipose-derived mesenchymal stem cells (ASCs) have shown therapeutic potentials against refractory diseases. However, the detailed therapeutic mechanisms remain unclear. Here, we report the therapeutic actions of human ASCs in nephritis, focusing on cellular dynamics and multi-organ networks. Intravenously-administered ASCs accumulated in spleen but not kidneys. Nevertheless, ASCs increased M2 macrophages and Tregs in kidneys and drove strong renoprotection. Splenectomy abolished these therapeutic effects. ASC-derived extracellular vesicles (EVs) were transferred to M2 macrophages, which entered the bloodstream from spleen. EVs induced the transcriptomic signatures of hyperpolarization and PGE2 stimulation in M2 macrophages and ameliorated glomerulonephritis. ASCs, ASC-derived EVs, and EV-transferred M2 macrophages enhanced Treg induction. These findings suggest that EV transfer from spleen-accumulated ASCs to M2 macrophages and subsequent modulation of renal immune-environment underlie the renoprotective effects of ASCs. Our results provide insights into the therapeutic actions of ASCs, focusing on EV-mediated modulation of macrophages and the spleen-kidney immune network.

The renoprotective effects of adipose-derived mesenchymal stem cells (ASCs) are enhanced through the transfer of EVs predominantly to M2 macrophages in the spleen, providing insights into therapeutic avenues for ASCs.

Extracellular Vesicles for Regenerative Medicine Applications

Tissue engineering and regenerative medicine (TERM) may be defined as a translational discipline focused on the development of novel techniques, devices, and materials to replace or repair injured or diseased tissue and organs. The main approaches typically use cells, scaffolds, and signaling molecules, either alone or in combination, to promote repair and regeneration. Although cells are required to create new functional tissue, the source of cells, either from an exogenous allogeneic or autologous source or through the recruitment of endogenous (autologous) cells, is technically challenging and risks the host rejection of new tissue. Regardless of the cell source, these approaches also require appropriate instruction for proliferation, differentiation, and in vivo spatial organization to create new functional tissue. Such instruction is supplied through the microenvironment where cells reside, environments which largely consist of the extracellular matrix (ECM). The specific components of the ECM, and broadly the extracellular space, responsible for promoting tissue regeneration and repair, are not fully understood, however extracellular vesicles (EVs) found in body fluids and solid phases of ECM have emerged as key mediators of tissue regeneration and repair. Additionally, these EVs might serve as potential cell-free tools in TERM to promote tissue repair and regeneration with minimal risk for host rejection and adverse sequelae. The past two decades have shown a substantial interest in understanding the therapeutic role of EVs and their applications in the context of TERM. Therefore, the purpose of this review is to highlight the fundamental characteristics of EVs, the current pre-clinical and clinical applications of EVs in TERM, and the future of EV-based strategies in TERM.