Characterization and Therapeutic Use of Extracellular Vesicles Derived from Platelets

Zedoarondiol Inhibits Neovascularization in Atherosclerotic Plaques of ApoE-/- Mice by Reducing Platelet Exosomes-Derived MiR-let-7a

OBJECTIVE

To investigate the effect of zedoarondiol on neovascularization of atherosclerotic (AS) plaque by exosomes experiment.

METHODS

ApoE-/- mice were fed with high-fat diet to establish AS model and treated with high- and low-dose (10, 5 mg/kg daily) of zedoarondiol, respectively. After 14 weeks, the expressions of anti-angiogenic protein thrombospondin 1 (THBS-1) and its receptor CD36 in plaques, as well as platelet activation rate and exosome-derived miR-let-7a were detected. Then, zedoarondiol was used to intervene in platelets in vitro, and miR-let-7a was detected in platelet-derived exosomes (Pexo). Finally, human umbilical vein endothelial cells (HUVECs) were transfected with miR-let-7a mimics and treated with Pexo to observe the effect of miR-let-7a in Pexo on tube formation.

RESULTS

Animal experiments showed that after treating with zedoarondiol, the neovascularization density in plaques of AS mice was significantly reduced, THBS-1 and CD36 increased, the platelet activation rate was markedly reduced, and the miR-let-7a level in Pexo was reduced (P<0.01). In vitro experiments, the platelet activation rate and miR-let-7a levels in Pexo were significantly reduced after zedoarondiol's intervention. Cell experiments showed that after Pexo's intervention, the tube length increased, and the transfection of miR-let-7a minics further increased the tube length of cells, while reducing the expressions of THBS-1 and CD36.

CONCLUSION

Zedoarondiol has the effect of inhibiting neovascularization within plaque in AS mice, and its mechanism may be potentially related to inhibiting platelet activation and reducing the Pexo-derived miRNA-let-7a level.

Microneedle patches: a new vantage point for diabetic wound treatments

Microneedle patches have emerged as a promising approach for diabetic wound healing by enabling the targeted delivery of therapeutic agents such as stem cells and their derived exosomes, as well as localized delivery of bioactive moieties. These patches offer a non-invasive and efficient method for administering therapeutic payloads directly to the site of the wound, bypassing systemic circulation and minimizing potential side effects. The targeted delivery of stem cells holds immense potential for promoting tissue regeneration and accelerating wound healing in diabetic patients. Similarly, the localized delivery of stem cell-derived exosomes, which are known for their regenerative and anti-inflammatory properties, can enhance the healing process. Furthermore, microneedle patches enable the precise and controlled release of bioactive moieties, such as growth factors and cytokines, directly to the wound site, creating a conducive microenvironment for tissue repair and regeneration. The challenges associated with microneedle patches for diabetic wound healing are multifaceted. Biocompatibility issues, variability in skin characteristics among diabetic patients, regulatory hurdles, scalability, cost considerations, long-term stability, and patient acceptance and compliance all present significant barriers to the widespread adoption and optimization of microneedle technology in clinical practice. Overcoming these challenges will require collaborative efforts from various stakeholders to advance the field and address critical gaps in research and development. Ongoing research focuses on enhancing the biocompatibility and mechanical properties of microneedle materials, developing customizable technologies for personalized treatment approaches, integrating advanced functionalities such as sensors for real-time monitoring, and improving patient engagement and adherence through education and support mechanisms. These advancements have the potential to improve diabetic wound management by providing tailored and precise therapies that promote faster healing and reduce complications. This review explores the current landscape of microneedle patches in the context of diabetic wound management, highlighting both the challenges that need to be addressed and future perspectives for this innovative treatment modality.

The potential utilization of platelet-derived extracellular vesicles in clinical treatment

Platelet-derived extracellular vesicles (PEVs) are released by platelets in the blood circulation, which carry a rich bio-molecular cargo influential in intercellular communications. PEVs can enter the lymph, bone marrow, and synovial fluid as nano-sized particles, while platelets cannot cross tissue barriers. Considering the advantages of PEVs such as low immunogenicity, high regulation of signal transduction, and easy obtainment, PEVs may be promising therapeutic tools for medical applications. The exceptional functional roles played by PEVs explain the recent interest in exploring new cell-free therapies that could address needs in angiogenesis, regenerative medicine, and targeted drug delivery. The review takes a critical look at the main advances of PEVs in the treatment of diseases by presenting the latest knowledge from the performed studies, in order to enhance the further translation of the PEVs research into feasible therapeutic applications.

Dissolvable microneedle-based wound dressing transdermally and continuously delivers anti-inflammatory and pro-angiogenic exosomes for diabetic wound treatment

Due to overactive inflammation and hindered angiogenesis, self-healing of diabetic wounds (DW) remains challenging in the clinic. Platelet-derived exosomes (PLT-Exos), a novel exosome capable of anti-inflammation and pro-angiogenesis, show great potential in DW treatment. However, previous administration of exosomes into skin wounds is topical daub or intradermal injection, which cannot intradermally deliver PLT-Exos into the dermis layer, thus impeding its long-term efficacy in anti-inflammation and pro-angiogenesis. Herein, a dissolvable microneedle-based wound dressing (PLT-Exos@ADMMA-MN) was developed for transdermal and long-term delivery of PLT-Exos. Firstly, a photo-crosslinking methacrylated acellular dermal matrix-based hydrogel (ADMMA-GEL), showing physiochemical tailorability, fast-gelling performance, excellent biocompatibility, and pro-angiogenic capacities, was synthesized as a base material of our dressing. For endowing the dressing with anti-inflammation and pro-angiogenesis, PLT-Exos were encapsulated into ADMMA-GEL with a minimum effective concentration determined by our in-vitro experiments. Then, in-vitro results show that this dressing exhibits excellent properties in anti-inflammation and pro-angiogenesis. Lastly, in-vivo experiments showed that this dressing could continuously and transdermally deliver PLT-Exos into skin wounds to switch local macrophage into M2 phenotype while stimulating neovascularization, thus proving a low-inflammatory and pro-angiogenic microenvironment for DW healing. Collectively, this study provides a novel wound dressing capable of suppressing inflammation and stimulating vascularization for DW treatment.

Modulating Immune Responses: The Double-Edged Sword of Platelet CD40L

The CD40-CD40L receptor ligand pair plays a fundamental role in the modulation of the innate as well as the adaptive immune response, regulating monocyte, T and B cell activation, and antibody isotype switching. Although the expression and function of the CD40-CD40L dyad is mainly attributed to the classical immune cells, the majority of CD40L is expressed by activated platelets, either in a membrane-bound form or shed as soluble molecules in the circulation. Platelet-derived CD40L is involved in the communication with different immune cell subpopulations and regulates their functions effectively. Thus, platelet CD40L contributes to the containment and clearance of bacterial and viral infections, and additionally guides leukocytes to sites of infection. However, platelet CD40L promotes inflammatory cellular responses also in a pathophysiological context. For example, in HIV infections, platelet CD40L is supportive of neuronal inflammation, damage, and finally HIV-related dementia. In sepsis, platelet CD40L can induce extensive endothelial and epithelial damage resulting in barrier dysfunction of the gut, whereby the translocation of microbiota into the circulation further aggravates the uncontrolled systemic inflammation. Nevertheless, a distinct platelet subpopulation expressing CD40L under septic conditions can attenuate systemic inflammation and reduce mortality in mice. This review focuses on recent findings in the field of platelet CD40L biology and its physiological and pathophysiological implications, and thereby highlights platelets as vital immune cells that are essential for a proper immune surveillance. In this context, platelet CD40L proves to be an interesting target for various inflammatory diseases. However, either an agonism or a blockade of CD40L needs to be well balanced since both the approaches can cause severe adverse events, ranging from hyperinflammation to immune deficiency. Thus, an interference in CD40L activities should be likely done in a context-dependent and timely restricted manner.

Platelet Vesicles Synergetic with Biosynthetic Cellulose Aerogels for Ultra-Fast Hemostasis and Wound Healing

Achieving hemostasis in penetrating and irregular wounds is challenging because the hemostasis factor cannot arrive at the bleeding site, and substantial bleeding will wash away the blood clot. Since the inherently gradual nature of blood clot formation takes time, a physical barrier is needed before blood clot formation. Herein, an ultra-light and shape memory hemostatic aerogel consisting of oxidized bacterial cellulose (OBC) and platelet extracellular vesicles (pVEs) is reported. The OBC-pVEs aerogel provides a physical barrier for the bleeding site by self-expansion, absorbing the liquid from blood to concentrate platelets and clotting factors and accelerating the clot formation by activating platelets and transforming fibrinogen into fibrin. In the rat liver and tail injury models, the blood loss decreases by 73% and 59%, and the bleeding times are reduced by 55% and 62%, respectively. OBC-pVEs aerogel has also been shown to accelerate wound healing. In conclusion, this work introduces an effective tool for treating deep, non-compressible, and irregular wounds and offers valuable strategies for trauma bleeding and wound treatment.

HWJMSC-EVs promote cartilage regeneration and repair via the ITGB1/TGF-β/Smad2/3 axis mediated by microfractures

The current first-line treatment for repairing cartilage defects in clinical practice is the creation of microfractures (MF) to stimulate the release of mesenchymal stem cells (MSCs); however, this method has many limitations. Recent studies have found that MSC-derived extracellular vesicles (MSC-EVs) play an important role in tissue regeneration. This study aimed to verify whether MSC-EVs promote cartilage damage repair mediated by MFs and to explore the repair mechanisms. In vitro experiments showed that human umbilical cord Wharton's jelly MSC-EVs (hWJMSC-EVs) promoted the vitality of chondrocytes and the proliferation and differentiation ability of bone marrow-derived MSCs. This was mainly because hWJMSC-EVs carry integrin beta-1 (ITGB1), and cartilage and bone marrow-derived MSCs overexpress ITGB1 after absorbing EVs, thereby activating the transforming growth factor-β/Smad2/3 axis. In a rabbit knee joint model of osteochondral defect repair, the injection of different concentrations of hWJMSC-EVs into the joint cavity showed that a concentration of 50 µg/ml significantly improved the formation of transparent cartilage after MF surgery. Extraction of regenerated cartilage revealed that the changes in ITGB1, transforming growth factor-β, and Smad2/3 were directly proportional to the repair of regenerated cartilage. In summary, this study showed that hWJMSC-EVs promoted cartilage repair after MF surgery.

Platelet-derived extracellular vesicles: a new-generation nanostructured tool for chronic wound healing

Chronic nonhealing wounds pose a serious challenge to regaining skin function and integrity. Platelet-derived extracellular vesicles (PEVs) are nanostructured particles with the potential to promote wound healing since they can enhance neovascularization and cell migration and reduce inflammation and scarring. This work provides an innovative overview of the technical laboratory issues in PEV production, PEVs' role in chronic wound healing and the benefits and challenges in its clinical translation. The article also explores the challenges of proper sourcing, extraction techniques and storage conditions, and discusses the necessity of further evaluations and combinational therapeutics, including dressing biomaterials, M2-derived exosomes, mesenchymal stem cells-derived extracellular vesicles and microneedle technology, to boost their therapeutic efficacy as advanced strategies for wound healing.

Platelet-derived microparticles and their cargos: The past, present and future

All eukaryotic cells can secrete extracellular vesicles, which have a double-membrane structure and are important players in the intercellular communication involved in a variety of important biological processes. Platelets form platelet-derived microparticles (PMPs) in response to activation, injury, or apoptosis. This review introduces the origin, pathway, and biological functions of PMPs and their importance in physiological and pathological processes. In addition, we review the potential applications of PMPs in cancer, vascular homeostasis, thrombosis, inflammation, neural regeneration, biomarkers, and drug carriers to achieve targeted drug delivery. In addition, we comprehensively report on the origin, biological functions, and applications of PMPs. The clinical transformation, high heterogeneity, future development direction, and limitations of the current research on PMPs are also discussed in depth. Evidence has revealed that PMPs play an important role in cell-cell communication, providing clues for the development of PMPs as carriers for relevant cell-targeted drugs. The development history and prospects of PMPs and their cargos are explored in this guidebook.

Platelet-derived drug delivery systems: Pioneering treatment for cancer, cardiovascular diseases, infectious diseases, and beyond

Platelets play a critical role as circulating cells in the human body and contribute to essential physiological processes such as blood clotting, hemostasis, vascular repair, and thrombus formation. Currently, platelets are extensively employed in the development of innovative biomimetic drug delivery systems, offering significant enhancements in circulation time, biocompatibility, and targeted delivery efficiency compared to conventional drug delivery approaches. Leveraging the unique physiological functions of platelets, these platelet-derived drug delivery systems (DDSs) hold great promise for the treatment of diverse diseases, including cancer, cardiovascular diseases, infectious diseases, wound healing and other diseases. This review primarily focuses on the design and characteristics of existing platelet-derived DDSs, including their preparation and characterization methods. Furthermore, this review comprehensively outlines the applications of these materials across various diseases, offering a holistic understanding of their therapeutic potential. This study aimed to provide a comprehensive overview of the potential value of these materials in clinical treatment, serving as a valuable reference for the advancement of novel platelet-derived DDSs and their broader utilization in the field of disease treatment.

Impact of production methods and storage conditions on extracellular vesicles in packed red blood cells and platelet concentrates

The use of blood and blood products can be life-saving, but there are also certain risks associated with their administration and use. Packed red blood cells (pRBCs) and platelet concentrates are the most commonly used blood products in transfusion medicine to treat anemia or acute and chronic bleeding disorders, respectively. During the production and storage of blood products, red blood cells and platelets release extracellular vesicles (EVs) as a result of the storage lesion, which may affect product quality. EVs are subcellular structures enclosed by a lipid bilayer and originate from the endosomal system or from the plasma membrane. They play a pivotal role in intercellular communication and are emerging as important regulators of inflammation and coagulation. Their cargo and their functional characteristics depend on the cell type from which they originate, as well as on their microenvironment, influencing their capacity to promote coagulation and inflammatory responses. Hence, the potential involvement of EVs in transfusion-related adverse events is increasingly recognized and studied. Here, we review the knowledge regarding the effect of production and storage conditions of pRBCs and platelet concentrates on the release of EVs. In this context, the mode of processing and anticoagulation, the influence of additive solutions and leukoreduction, as well as the storage duration will be addressed, and we discuss potential implications of EVs for the clinical outcome of transfusion.

Platelet-rich plasma-derived exosomes promote rotator cuff tendon-bone healing

BACKGROUND

Rotator cuff tear (RCT) is the most common type of shoulder joint injury, platelet-rich plasma-derived exosomes (PRP-exos) are highly promising in tissue repair and regeneration. The purpose of this study was to determine the function of PRP-exos in rotator cuff tendon-bone healing.

METHODS

PRP-exos were isolated from the rabbit whole blood by differential ultracentrifugation and characterized through transmission electron microscopy assay, nanoparticle tracking analysis, and western blotting. Alkaline phosphatase and Von Kossa staining were used to show tendon-derived stem cell (TDSC) differentiation. RT-qPCR and western blotting were performed to detect COL II, SOX-9, and TIMP-1. To determine the therapeutic effects of PRP-exos in vivo. Thirty New Zealand white rabbits were divided into control, model, and PRP-exos groups. The RCT animal model was constructed. The changes in tendon-bone tissue were determined by HE staining. Contents of COL-II, SOX-9, and TIMP-1 were determined by immunohistochemistry staining.

RESULTS

PRP-exos were successfully isolated from rabbit blood. PRP-exos promoted TDSC proliferation and differentiation and also induced tendon-specific markers COL II, SOX-9, and TIMP-1 production. In vivo study revealed that PRP-exos promoted early healing of injured tendons. Rabbits treated with PRP-exos had better tissue arrangement in the tear site. Additionally, the contents of COL II, SOX-9, and TIMP-1 were also increased in the RCT rabbit model after PRP-exos treatment.

CONCLUSIONS

PRP-exos enhanced tendon-bone healing by promoting TDSC proliferation and differentiation. This finding indicates that PRP-exos can serve as a promising strategy to treat rotator cuff tendon-bone healing.

Hydrogel-mediated delivery of platelet-derived exosomes: Innovations in tissue engineering

In this scholarly review, we conduct a thorough examination of the significant role played by platelet-derived exosomes (Plt-Exos) and hydrogels in the fields of tissue engineering and regenerative medicine. Our detailed investigation highlights the central involvement of Plt-Exos in various physiological and pathological processes, underscoring their potential contributions to diverse areas such as wound healing, neural rejuvenation, and cancer progression. Despite the promising therapeutic aspects, the notable variability in the isolation and characterization of pEVs underscores the need for a more rigorous and standardized methodology. Shifting our focus to hydrogels, they have emerged as promising biomaterials relevant to tissue engineering and regenerative medicine. Their unique characteristics, especially their chemical and physical adaptability, along with the modifiability of their biochemical properties, make hydrogels a captivating subject. These exceptional features open avenues for numerous tissue engineering applications, facilitating the delivery of essential growth factors, cytokines, and microRNAs. This analysis explores the innovative integration of Plt-Exos with hydrogels, presenting a novel paradigm in tissue engineering. Through the incorporation of Plt-Exos into hydrogels, there exists an opportunity to enhance tissue regeneration endeavors by combining the bioactive features of Plt-Exos with the restorative capabilities of hydrogel frameworks. In conclusion, the cooperative interaction between platelet-derived exosomes and hydrogels indicates a promising path in tissue engineering and regenerative medicine. Nevertheless, the successful execution of this approach requires a deep understanding of molecular dynamics, coupled with a dedication to refining isolation techniques.

Platelet-derived extracellular vesicles play an important role in platelet transfusion therapy

Extracellular vesicles (EVs) contain the characteristics of their cell of origin and mediate cell-to-cell communication. Platelet-derived extracellular vesicles (PEVs) not only have procoagulant activity but also contain platelet-derived inflammatory factors (CD40L and mtDNA) that mediate inflammatory responses. Studies have shown that platelets are activated during storage to produce large amounts of PEVs, which may have implications for platelet transfusion therapy. Compared to platelets, PEVs have a longer storage time and greater procoagulant activity, making them an ideal alternative to platelets. This review describes the reasons and mechanisms by which PEVs may have a role in blood transfusion therapy.

The value of platelet-rich plasma-derived extracellular vesicles in modern medicine

Platelet-rich plasma (PRP) has been widely used in clinical practice. The mechanism by which PRP promotes tissue repair lies in the release of multiple growth factors upon platelet activation, which accelerates the proliferation and differentiation of repair cells and the synthesis of extracellular matrix. In recent years, as extracellular vesicles (EVs) research has increased and intensified, it has been found that EVs also play an important role in tissue repair. This article provides a comprehensive review of the role of PRP and PRP-derived extracellular vesicles (PRP-EVs) in tissue repair. It discusses the biological characteristics, extraction, identification, activation, and preservation of PRP-EVs. It also reviews their applications in orthopedics and wound repair. The article highlights the importance of PRP-EVs in modern medicine and suggests that they could be a promising natural nanocarrier.

Platelet and mitochondrial RNA is decreased in plasma-derived extracellular vesicles in women with preeclampsia-an exploratory study

BACKGROUND

Circulating extracellular vesicles (EVs) are increased in preeclampsia (PE) and are associated with severity and progression. We examined in this exploratory cohort study if the mRNAs and long noncoding RNAs (lncRNAs) in plasma-derived EVs were dysregulated in PE compared to normal pregnancy and display different temporal patterns during gestation.

METHODS

We isolated EVs from plasma at weeks 22-24 and 36-38 in women with and without PE (n=7 in each group) and performed RNA-seq, focusing on mRNAs and lncRNAs. We validated highly expressed mitochondrial and platelet-derived RNAs discovered from central pathways in 60 women with/without PE. We examined further one of the regulated RNAs, noncoding mitochondrially encoded tRNA alanine (MT-TA), in leukocytes and plasma to investigate its biomarker potential and association with clinical markers of PE.

RESULTS

We found abundant levels of platelet-derived and mitochondrial RNAs in EVs. Expression of these RNAs were decreased and lncRNAs increased in EVs from PE compared to without PE. These findings were further validated by qPCR for mitochondrial RNAs MT-TA, MT-ND2, MT-CYB and platelet-derived RNAs PPBP, PF4, CLU in EVs. Decreased expression of mitochondrial tRNA MT-TA in leukocytes at 22-24 weeks was strongly associated with the subsequent development of PE.

CONCLUSIONS

Platelet-derived and mitochondrial RNA were highly expressed in plasma EVs and were decreased in EVs isolated from women with PE compared to without PE. LncRNAs were mostly increased in PE. The MT-TA in leukocytes may be a useful biomarker for prediction and/or early detection of PE.

Plasma-derived extracellular vesicle surface markers CD45, CD326 and CD56 correlate with the stage of osteoarthritis: a primary study of a novel and promising diagnostic tool of the disease

Recently, there is a growing interest in the research based on extracellular vesicles (EVs) which represent paracrine factors secreted by almost all cell types. Both, normal and pathological cells are able to release various types of EVs with different physiological properties, functions and compositions. EVs play an important role in intercellular communication, mechanism and tissue repair. Moreover, EVs could help not only in the treatment of diseases but also in their diagnostics. This work focused on the evaluation of the potential of EVs being used as biomarkers for the diagnosis of osteoarthritis (OA) based on a comparison of the composition of EVs separated from platelet-poor plasma (PPP) of healthy donors and OA patients at different stages of OA. OA is established as a complex syndrome with extensive impact on multiple tissues within the synovial joint. It is a chronic disease of musculoskeletal system that mainly affects the elderly. Depending on the use of the Kellgren-Lawrence classification system, there are four grades of OA which have a negative impact on patients' quality of life. It is very difficult to detect OA in its early stages, so it is necessary to find a new diagnostic method for its timely detection. PPP samples were prepared from whole blood. PPP-EVs were separated from 3 groups of donors-healthy control, early stage OA, end-stage OA, and their content was compared and correlated. EVs from PPP were separated by size exclusion chromatography and characterized in terms of their size, yield and purity by NTA, western blotting, ELISA and flow cytometry. Detection of surface markers expression in EVs was performed using MACSPlex approach. Inflammatory and growth factors in EVs were analysed using MAGPix technology. Our study confirmed significant differences between EVs surface markers of patients and healthy controls correlating with the age of donor (CD63, CD31 and ROR1) and stage of OA (CD45, CD326 and CD56), respectively. Circulating EVs have been under extensive investigation for their capability to predict OA pathology diagnosis as potential targets for biomarker discovery. Taken together, obtained results indicated that PPP-EVs surface markers could be used as potential biomarkers in the early diagnosis of OA.

Fiber-reinforced gelatin/β-cyclodextrin hydrogels loaded with platelet-rich plasma-derived exosomes for diabetic wound healing

Diabetic complications with high-glucose status (HGS) cause the dysregulated autophagy and excessive apoptosis of multiple-type cells, leading to the difficulty in wound self-healing. Herein, we firstly developed fiber-reinforced gelatin (GEL)/β-cyclodextrin (β-CD) therapeutic hydrogels by the modification of platelet-rich plasma exosomes (PRP-EXOs). The GEL fibers that were uniformly dispersed within the GEL/β-CD hydrogels remarkably enhanced the compression strengths and viscoelasticity. The PRP-EXOs were encapsulated in the hydrogels via the covalent crosslinking between the PRP-EXOs and genipin. The diabetic rat models demonstrated that the GEL/β-CD hydrogels and PRP-EXOs cooperatively promoted diabetic wound healing. On the one hand, the GEL/β-CD hydrogels provided the biocompatible microenvironments and active components for cell adhesion, proliferation and skin tissue regeneration. On the other hand, the PRP-EXOs in the therapeutic hydrogels significantly activated the autophagy and inhibited the apoptosis of human umbilical vein endothelial cells (HUVECs) and human skin fibroblasts (HSFs). The activation of autophagy and inhibition of apoptosis in HUVECs and HSFs induced the blood vessel creation, collagen formation and re-epithelialization. Taken together, this work proved that the incorporation of PRP-EXOs in a wound dressing was an effective strategy to regulate autophagy and apoptosis, and provide a novel therapeutic platform for diabetic wound healing.

Ozone and procaine increase secretion of platelet-derived factors in platelet-rich plasma

Platelet-rich plasma (PRP) is gaining more and more attention in regenerative medicine as an innovative and efficient therapeutic approach. The regenerative properties of PRP rely on the numerous bioactive molecules released by the platelets: growth factors are involved in proliferation and differentiation of endothelial cells and fibroblasts, angiogenesis and extracellular matrix formation, while cytokines are mainly involved in immune cell recruitment and inflammation modulation. Attempts are ongoing to improve the therapeutic potential of PRP by combining it with agents able to promote regenerative processes. Two interesting candidates are ozone, administered at low doses as gaseous oxygen-ozone mixtures, and procaine. In the present study, we investigated the effects induced on platelets by the in vitro treatment of PRP with ozone or procaine, or both. We combined transmission electron microscopy to obtain information on platelet modifications and bioanalytical assays to quantify the secreted factors. The results demonstrate that, although platelets were already activated by the procedure to prepare PRP, both ozone and procaine induced differential morpho-functional modifications in platelets resulting in an increased release of factors. In detail, ozone induced an increase in surface protrusions and open canalicular system dilation suggestive of a marked α-granule release, while procaine caused a decrease in surface protrusions and open canalicular system dilation but a remarkable increase in microvesicle release suggestive of high secretory activity. Consistently, nine of the thirteen platelet-derived factors analysed in the PRP serum significantly increased after treatment with ozone and/or procaine. Therefore, ozone and procaine proved to have a remarkable stimulating potential without causing any damage to platelets, probably because they act through physiological, although different, secretory pathways.

Circulating Small Extracellular Vesicles Reflect the Severity of Myocardial Damage in STEMI Patients

Circulating small extracellular vesicles (sEVs) contribute to inflammation, coagulation and vascular injury, and have great potential as diagnostic markers of disease. The ability of sEVs to reflect myocardial damage assessed by Cardiac Magnetic Resonance (CMR) in ST-segment elevation myocardial infarction (STEMI) is unknown. To fill this gap, plasma sEVs were isolated from 42 STEMI patients treated by primary percutaneous coronary intervention (pPCI) and evaluated by CMR between days 3 and 6. Nanoparticle tracking analysis showed that sEVs were greater in patients with anterior STEMI (p = 0.0001), with the culprit lesion located in LAD (p = 0.045), and in those who underwent late revascularization (p = 0.038). A smaller sEV size was observed in patients with a low myocardial salvage index (MSI, p = 0.014). Patients with microvascular obstruction (MVO) had smaller sEVs (p < 0.002) and lower expression of the platelet marker CD41-CD61 (p = 0.039). sEV size and CD41-CD61 expression were independent predictors of MVO/MSI (OR [95% CI]: 0.93 [0.87-0.98] and 0.04 [0-0.61], respectively). In conclusion, we provide evidence that the CD41-CD61 expression in sEVs reflects the CMR-assessed ischemic damage after STEMI. This finding paves the way for the development of a new strategy for the timely identification of high-risk patients and their treatment optimization.

Expanding applications of allogeneic platelets, platelet lysates, and platelet extracellular vesicles in cell therapy, regenerative medicine, and targeted drug delivery

Platelets are small anucleated blood cells primarily known for their vital hemostatic role. Allogeneic platelet concentrates (PCs) collected from healthy donors are an essential cellular product transfused by hospitals to control or prevent bleeding in patients affected by thrombocytopenia or platelet dysfunctions. Platelets fulfill additional essential functions in innate and adaptive immunity and inflammation, as well as in wound-healing and tissue-repair mechanisms. Platelets contain mitochondria, lysosomes, dense granules, and alpha-granules, which collectively are a remarkable reservoir of multiple trophic factors, enzymes, and signaling molecules. In addition, platelets are prone to release in the blood circulation a unique set of extracellular vesicles (p-EVs), which carry a rich biomolecular cargo influential in cell-cell communications. The exceptional functional roles played by platelets and p-EVs explain the recent interest in exploring the use of allogeneic PCs as source material to develop new biotherapies that could address needs in cell therapy, regenerative medicine, and targeted drug delivery. Pooled human platelet lysates (HPLs) can be produced from allogeneic PCs that have reached their expiration date and are no longer suitable for transfusion but remain valuable source materials for other applications. These HPLs can substitute for fetal bovine serum as a clinical grade xeno-free supplement of growth media used in the in vitro expansion of human cells for transplantation purposes. The use of expired allogeneic platelet concentrates has opened the way for small-pool or large-pool allogeneic HPLs and HPL-derived p-EVs as biotherapy for ocular surface disorders, wound care and, potentially, neurodegenerative diseases, osteoarthritis, and others. Additionally, allogeneic platelets are now seen as a readily available source of cells and EVs that can be exploited for targeted drug delivery vehicles. This article aims to offer an in-depth update on emerging translational applications of allogeneic platelet biotherapies while also highlighting their advantages and limitations as a clinical modality in regenerative medicine and cell therapies.

Platelet-Derived Exosomes Alleviate Knee Osteoarthritis by Attenuating Cartilage Degeneration and Subchondral Bone Loss

BACKGROUND

Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease among the aged population. However, current treatments for OA are limited to alleviating symptoms, with no therapies that prevent and regenerate cartilage deterioration.

PURPOSE

To assess the effects of platelet-derived exosomes (Plt-exos) on OA and then to explore the potential molecular mechanism.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosomes derived from human apheresis platelets were isolated and identified. The effects of Plt-exos in protecting chondrocytes under interleukin 1β stimulation were evaluated by analyzing the proliferation and migration in human primary chondrocytes. RNA sequencing was later performed in vitro for primary chondrocytes to reveal the underlying mechanisms of Plt-exo treatment. Anterior cruciate ligament transection was used to construct an OA mice model, and intra-articular injection of Plt-exos was given once a week for 6 weeks. Mice were sacrificed 4 weeks after the last injection. Histologic and immunohistochemistry staining and micro-computed tomography analysis were performed to assess alterations of articular cartilage and subchondral bone.

RESULTS

Plt-exos significantly promoted proliferation and migration of chondrocytes within a dose-dependent manner, as well as dramatically promoted cartilage regeneration and attenuated abnormal tibial subchondral bone remodeling, thus slowing the progression of OA. After being treated with Plt-exos, 1797 genes were differentially expressed in chondrocytes (923 upregulated and 874 downregulated genes). Functional enrichment results and hub genes were mainly involved in anti-inflammatory effects, mediating cell adhesion, stimulating cartilage repair, promoting anabolism, and inhibiting catabolism.

CONCLUSION

Our results demonstrated that Plt-exos promoted chondrocyte proliferation and migration in vitro, as well as attenuated cartilage degeneration, improved the microarchitecture of subchondral bone, and retarded OA progression in vivo.

CLINICAL RELEVANCE

Our study illustrated that the administered Plt-exos could alleviate knee OA by attenuating cartilage degeneration and subchondral bone loss, possibly serving as a novel promising treatment for OA in the future.

Platelet-Derived Extracellular Vesicles as Lipid Carriers in Severe Allergic Inflammation

The resolution of inflammation is a complex process that is critical for removing inflammatory cells and restoring tissue function. The dysregulation of these mechanisms leads to chronic inflammatory disorders. Platelets, essential cells for preserving homeostasis, are thought to play a role in inflammation as they are a source of immunomodulatory factors. Our aim was to identify key metabolites carried by platelet-derived extracellular vesicles (PL-EVs) in a model of allergic inflammation. PL-EVs were isolated by serial ultracentrifugation using platelet-rich plasma samples obtained from platelet apheresis from severely (n = 6) and mildly (n = 6) allergic patients and non-allergic individuals used as controls (n = 8). PL-EVs were analysed by a multiplatform approach using liquid and gas chromatography coupled to mass spectrometry (LC-MS and GC-MS, respectively). PL-EVs obtained from severely and mildly allergic patients and control individuals presented comparable particle concentrations and sizes with similar protein concentrations. Strikingly, PL-EVs differed in their lipid and metabolic content according to the severity of inflammation. L-carnitine, ceramide (Cer (d18:0/24:0)), and several triglycerides, all of which seem to be involved in apoptosis and regulatory T functions, were higher in PL-EVs from patients with mild allergic inflammation than in those with severe inflammation. In contrast, PL-EVs obtained from patients with severe allergic inflammation showed an alteration in the arachidonic acid pathway. This study demonstrates that PL-EVs carry specific lipids and metabolites according to the degree of inflammation in allergic patients and propose novel perspectives for characterising the progression of allergic inflammation.

Platelet extracellular vesicles: Darkness and light of autoimmune diseases

Autoimmune diseases are characterized by a breakdown of immune tolerance, leading to inflammation and irreversible end-organ tissue damage. Platelet extracellular vesicles are cellular elements that are important in blood circulation and actively participate in inflammatory and immune responses through intercellular communication and interactions between inflammatory cells, immune cells, and their secreted factors. Therefore, platelet extracellular vesicles are the "accelerator" in the pathological process of autoimmune diseases; however, this robust set of functions of platelet extracellular vesicles has also prompted new advances in therapeutic strategies for autoimmune diseases. In this review, we update fundamental mechanisms based on platelet extracellular vesicles communication function in autoimmune diseases. We also focus on the potential role of platelet extracellular vesicles for the treatment of autoimmune diseases. Some recent studies have found that antiplatelet aggregation drugs, specific biological agents can reduce the release of platelet extracellular vesicles. Platelet extracellular vesicles can also serve as vehicles to deliver drugs to targeted cells. It seems that we can try to silence or inhibit microRNA carried by platelet extracellular vesicles transcription and regulate the target cells to treat autoimmune diseases as platelet extracellular vesicles can transfer microRNA to other cells to regulate immune-inflammatory responses. Hopefully, the information presented here will provide hope for patients with autoimmune diseases.

Platelet-Derived Microparticles and Autoimmune Diseases

Extracellular microparticles provide a means of cell-to-cell communication and can promote information exchanges between adjacent or distant cells. Platelets are cell fragments that are derived from megakaryocytes. Their main functions are to stop bleeding, regulate inflammation, and maintain the integrity of blood vessels. When platelets are activated, they can perform related tasks by secreting platelet-derived microparticles that contain lipids, proteins, nucleic acids, and even organelles. There are differences in the circulating platelet levels in many autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, antiphospholipid antibody syndrome, and Sjogren's syndrome. In this paper, the latest findings in the research field of platelet-derived microparticles are reviewed, including the potential pathogenesis of platelet-derived microparticles in various types of immune diseases, their potential as related markers, and for monitoring the progress and prognosis of disease treatment are expounded.

Sphingosine-1-phosphate derived from PRP-Exos promotes angiogenesis in diabetic wound healing via the S1PR1/AKT/FN1 signalling pathway

Background

Sphingosine-1-phosphate (S1P), a key regulator of vascular homeostasis and angiogenesis, is enriched in exosomes derived from platelet-rich plasma (PRP-Exos). However, the potential role of PRP-Exos-S1P in diabetic wound healing remains unclear. In this study, we investigated the underlying mechanism of PRP-Exos-S1P in diabetic angiogenesis and wound repair.

Methods

Exosomes were isolated from PRP by ultracentrifugation and analysed by transmission electron microscopy, nanoparticle tracking analysis and western blotting. The concentration of S1P derived from PRP-Exos was measured by enzyme-linked immunosorbent assay. The expression level of S1P receptor1-3 (S1PR1-3) in diabetic skin was analysed by Q-PCR. Bioinformatics analysis and proteomic sequencing were conducted to explore the possible signalling pathway mediated by PRP-Exos-S1P. A diabetic mouse model was used to evaluate the effect of PRP-Exos on wound healing. Immunofluorescence for cluster of differentiation 31 (CD31) was used to assess angiogenesis in a diabetic wound model.

Results

In vitro, PRP-Exos significantly promoted cell proliferation, migration and tube formation. Furthermore, PRP-Exos accelerated the process of diabetic angiogenesis and wound closure in vivo. S1P derived from PRP-Exos was present at a high level, and S1PR1 expression was significantly elevated compared with S1PR2 and S1PR3 in the skin of diabetic patients and animals. However, cell migration and tube formation were not promoted by PRP-Exos-S1P in human umbilical vein endothelial cells treated with shS1PR1. In the diabetic mouse model, inhibition of S1PR1 expression at wounding sites decreased the formation of new blood vessels and delayed the process of wound closure. Bioinformatics analysis and proteomics indicated that fibronectin 1 (FN1) was closely related to S1PR1 due to its colocalization in the endothelial cells of human skin. Further study supported that FN1 plays an important role in the PRP-Exos-S1P-mediated S1PR1/protein kinase B signalling pathway.

Conclusions

PRP-Exos-S1P promotes angiogenesis in diabetic wound healing via the S1PR1/protein kinase B/FN1 signalling pathway. Our findings provide a preliminary theoretical foundation for the treatment of diabetic foot ulcers using PRP-Exos in the future.

HWJMSC-derived extracellular vesicles ameliorate IL-1β-induced chondrocyte injury through regulation of the BMP2/RUNX2 axis via up-regulation TFRC

Articular osteochondral injury is a common and frequently occurring disease in orthopedics that is caused by aging, disease, and trauma. The cytokine interleukin-1β (IL-1β) is a crucial mediator of the inflammatory response, which exacerbates damage during chronic disease and acute tissue injury. Human Wharton's jelly mesenchymal stem cell (HWJMSC) extracellular vesicles (HWJMSC-EVs) have been shown to promote cartilage regeneration. The study aimed to investigate the influence and mechanisms of HWJMSC-EVs on the viability, apoptosis, and cell cycle of IL-1β-induced chondrocytes. HWJMSC-EVs were isolated by Ribo™ Exosome Isolation Reagent kit. Nanoparticle tracking analysis was used to determine the size and concentration of HWJMSC-EVs. We characterized HWJMSC-EVs by western blot and transmission electron microscope. The differentiation, viability, and protein level of chondrocytes were measured by Alcian blue staining, Cell Counting Kit-8, and western blot, respectively. Flow cytometer was used to determine apoptosis and cell cycle of chondrocytes. The results showed that HWJMSCs relieved IL-1β-induced chondrocyte injury by inhibiting apoptosis and elevating viability and cell cycle of chondrocyte, which was reversed with exosome inhibitor (GW4869). HWJMSC-EVs were successfully extracted and proven to be uptake by chondrocytes. HWJMSC-EVs ameliorate IL-1β-induced chondrocyte injury by inhibiting cell apoptosis and elevating viability and cycle of cell, but these effects were effectively reversed by knockdown of transferrin receptor (TFRC). Notably, using bone morphogenetic protein 2 (BMP2) pathway agonist and inhibitor suggested that HWJMSC-EVs ameliorate IL-1β-induced chondrocyte injury through activating the BMP2 pathway via up-regulation TFRC. Furthermore, over-expression of runt-related transcription factor 2 (RUNX2) reversed the effects of BMP2 pathway inhibitor promotion of IL-1β-induced chondrocyte injury. These results suggested that HWJMSC-EVs ameliorate IL-1β-induced chondrocyte injury by regulating the BMP2/RUNX2 axis via up-regulation TFRC. HWJMSC-EVs may play a new insight for early medical interventions in patients with articular osteochondral injury.

Soluble and EV-Associated Diagnostic and Prognostic Biomarkers in Knee Osteoarthritis Pathology and Detection

Osteoarthritis (OA) is the most common degenerative disease of the connective tissue of the human musculoskeletal system. Despite its widespread prevalence, there are many limitations in its diagnosis and treatment. OA diagnosis currently relies on the presence of clinical symptoms, sometimes accompanied by changes in joint X-rays or MRIs. Biomarkers help not only to diagnose early disease progression but also to understand the process of OA in many ways. In this article, we briefly summarize information on articular joints and joint tissues, the pathogenesis of OA and review the literature about biomarkers in the field of OA, specifically inflammatory cytokines/chemokines, proteins, miRNA, and metabolic biomarkers found in the blood, synovial fluid and in extracellular vesicles.

Tendon tissue engineering: An overview of biologics to promote tendon healing and repair

Tendons are dense connective tissues with a hierarchical polarized structure that respond to and adapt to the transmission of muscle contraction forces to the skeleton, enabling motion and maintaining posture. Tendon injuries, also known as tendinopathies, are becoming more common as populations age and participation in sports/leisure activities increases. The tendon has a poor ability to self-heal and regenerate given its intrinsic, constrained vascular supply and exposure to frequent, severe loading. There is a lack of understanding of the underlying pathophysiology, and it is not surprising that disorder-targeted medicines have only been partially effective at best. Recent tissue engineering approaches have emerged as a potential tool to drive tendon regeneration and healing. In this review, we investigated the physiochemical factors involved in tendon ontogeny and discussed their potential application in vitro to reproduce functional and self-renewing tendon tissue. We sought to understand whether stem cells are capable of forming tendons, how they can be directed towards the tenogenic lineage, and how their growth is regulated and monitored during the entire differentiation path. Finally, we showed recent developments in tendon tissue engineering, specifically the use of mesenchymal stem cells (MSCs), which can differentiate into tendon cells, as well as the potential role of extracellular vesicles (EVs) in tendon regeneration and their potential for use in accelerating the healing response after injury.

Human Blood Extracellular Vesicles Activate Transcription of NF-kB-Dependent Genes in A549 Lung Adenocarcinoma Cells

Extracellular vesicles (EVs) produced by various cell types are heterogeneous in size and composition. Changes in the RNA sets of EVs in biological fluids are considered the basis for the development of new approaches to minimally invasive diagnostics and the therapy of human diseases. In this study, EVs were obtained from the blood of healthy donors by centrifugation, followed by ultracentrifugation. It was shown that EVs consist of several populations including small exosome-like vesicles and larger microvesicle-like particles. The composition of EVs' RNAs was determined. A549 lung adenocarcinoma cells were incubated with EV and the NGS analysis of differentially expressed genes was performed. During the incubation of A549 cells with EVs, the levels of mRNA encoding components for the NF-kB signaling pathway increased, as well as the expression of genes controlled by the NF-kB transcription factor. Overall, our results suggest that components of EVs trigger the NF-kB signaling cascade in A549 cells, leading to the transcription of genes including cytokines, adhesion molecules, cell cycle regulators, and cell survival factors. Our data provide insight into the interaction between blood EVs and human cells and can be used for designing new tools for the diagnosis and treatment of human diseases.

Extracellular Vesicles in Regenerative Processes Associated with Muscle Injury Recovery of Professional Athletes Undergoing Sub Maximal Strength Rehabilitation

Platelet-rich plasma (PRP) has great potential in regenerative medicine. In addition to the well-known regenerative potential of secreted growth factors, extracellular vesicles (EVs) are emerging as potential key players in the regulation of tissue repair. However, little is known about their therapeutic potential as regenerative agents. In this study, we have identified and subtyped circulating EVs (platelet-, endothelial-, and leukocyte-derived EVs) in the peripheral blood of athletes recovering from recent muscular injuries and undergoing a submaximal strength rehabilitation program. We found a significant increase in circulating platelet-derived EVs at the end of the rehabilitation program. Moreover, EVs from PRP samples were isolated by fluorescence-activated cell sorting and analyzed by label-free proteomics. The proteomic analysis of PRP-EVs revealed that 32% of the identified proteins were associated to "defense and immunity", and altogether these proteins were involved in vesicle-mediated transport (GO: 0016192; FDR = 3.132 × 10^-19), as well as in wound healing (GO: 0042060; FDR = 4.252 × 10^-13) and in the events regulating such a process (GO: 0061041; FDR = 2.812 × 10^-12). Altogether, these data suggest that platelet-derived EVs may significantly contribute to the regeneration potential of PRP preparations.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Wound Healing

The well-orchestrated process of wound healing may be negatively impacted from interrupted or incomplete tissue regenerative processes. The healing potential is further compromised in patients with diabetes mellitus, chronic venous insufficiency, critical limb ischemia, and immunocompromised conditions, with a high health care burden and expenditure. Stem cell-based therapy has shown promising results in clinical studies. Mesenchymal stem cell-derived exosomes (MSC Exos) may favorably impact intercellular signaling and immunomodulation, promoting neoangiogenesis, collagen synthesis, and neoepithelization. This article gives an outline of the biogenesis and mechanism of extracellular vesicles (EVs), particularly exosomes, in the process of tissue regeneration and discusses the use of preconditioned exosomes, platelet-rich plasma-derived exosomes, and engineered exosomes in three-dimensional bioscaffolds such as hydrogels (collagen and chitosan) to prolong the contact time of exosomes at the recipient site within the target tissue. An appropriate antibiotic therapy based on culture-specific guidance coupled with the knowledge of biopolymers helps to fabricate nanotherapeutic materials loaded with MSC Exos to effectively deliver drugs locally and promote novel approaches for the management of chronic wounds.

Platelets and platelet extracellular vesicles in drug delivery therapy: A review of the current status and future prospects

Platelets are blood cells that are primarily produced by the shedding of megakaryocytes in the bone marrow. Platelets participate in a variety of physiological and pathological processes in vivo, including hemostasis, thrombosis, immune-inflammation, tumor progression, and metastasis. Platelets have been widely used for targeted drug delivery therapies for treating various inflammatory and tumor-related diseases. Compared to other drug-loaded treatments, drug-loaded platelets have better targeting, superior biocompatibility, and lower immunogenicity. Drug-loaded platelet therapies include platelet membrane coating, platelet engineering, and biomimetic platelets. Recent studies have indicated that platelet extracellular vesicles (PEVs) may have more advantages compared with traditional drug-loaded platelets. PEVs are the most abundant vesicles in the blood and exhibit many of the functional characteristics of platelets. Notably, PEVs have excellent biological efficacy, which facilitates the therapeutic benefits of targeted drug delivery. This article provides a summary of platelet and PEVs biology and discusses their relationships with diseases. In addition, we describe the preparation, drug-loaded methods, and specific advantages of platelets and PEVs targeted drug delivery therapies for treating inflammation and tumors. We summarize the hot spots analysis of scientific articles on PEVs and provide a research trend, which aims to give a unique insight into the development of PEVs research focus.

One night of sleep deprivation induces release of small extracellular vesicles into circulation and promotes platelet activation by small EVs

Extracellular vesicles (EVs) are emerging as key players in intercellular communication. Few studies have focused on EV levels in subjects with sleep disorders. Here, we aimed to explore the role of acute sleep deprivation on the quantity and functionality of circulating EVs, and their tissue distribution. EVs were isolated by ultracentrifugation from the plasma of volunteers and animals undergoing one night of sleep deprivation. Arterio-venous shunt, FeCl₃ thrombus test and thrombin-induced platelet aggregation assay were conducted to evaluate the in vivo and in vitro bioactivity of small EVs. Western blotting was performed to measure the expression of EV proteins. The fate and distribution of circulating small EVs were determined by intravital imaging. We found that one night of sleep deprivation triggers release of small EVs into the circulation in both healthy individuals and animals. Injection of sleep deprivation-liberated small EVs into animals increased thrombus formation and weight in thrombosis models. Also, sleep deprivation-liberated small EVs promoted platelet aggregation induced by thrombin. Mechanistically, sleep deprivation increased the levels of HMGB1 protein in small EVs, which play important roles in platelet activation. Furthermore, we found sleep deprivation-liberated small EVs are more readily localize in the liver. These data suggested that one night of sleep deprivation is a stress for small EV release, and small EVs released here may increase the risk of thrombosis. Further, small EVs may be implicated in long distance signalling during sleep deprivation-mediated adaptation processes.

COVID-19 inflammation and implications in drug delivery

Growing evidence indicates that hyperinflammatory syndrome and cytokine storm observed in COVID-19 severe cases are narrowly associated with the disease's poor prognosis. Therefore, targeting the inflammatory pathways seems to be a rational therapeutic strategy against COVID-19. Many anti-inflammatory agents have been proposed; however, most of them suffer from poor bioavailability, instability, short half-life, and undesirable biodistribution resulting in off-target effects. From a pharmaceutical standpoint, the implication of COVID-19 inflammation can be exploited as a therapeutic target and/or a targeting strategy against the pandemic. First, the drug delivery systems can be harnessed to improve the properties of anti-inflammatory agents and deliver them safely and efficiently to their therapeutic targets. Second, the drug carriers can be tailored to develop smart delivery systems able to respond to the microenvironmental stimuli to release the anti-COVID-19 therapeutics in a selective and specific manner. More interestingly, some biosystems can simultaneously repress the hyperinflammation due to their inherent anti-inflammatory potency and endow their drug cargo with a selective delivery to the injured sites.

Platelet Extracellular Vesicles Are Taken up by Canine T Lymphocytes but Do Not Play a Role in Their Proliferation, Differentiation and Cytokine Production In Vitro

Eukaryotic and prokaryotic cells in physiological and pathological conditions form membrane-bound extracellular vesicles, known as EVs. The ability of these submicron structures to transfer their cargoes (miRNA, DNA, protein, cytokines, receptors, etc.) into recipient cells is described. Recent data revealed that platelet-derived extracellular vesicles (PEVs) crosstalk promotes cancer growth and metastasis formation. Moreover, they exert immunosuppressive activities on phagocytes. This EV subpopulation is the most abundant amongst all types in circulation. According to the authors' best knowledge, there is no information regarding the impact of PEVs on canine lymphocytes. The aim of this study was to evaluate the influence of PEVs on lymphocyte proliferation, phenotype and cytokine production in vitro. In the study, it was demonstrated (i) that PEVs interact differently with lymphocyte subsets and are preferentially associated with T-lymphocytes PBMC, while (ii) they are rarely detected in association with B-lymphocytes, and there is evidence that (iii) PEV uptake is observed after 7 h of co-culturing with lymphocytes. In addition, obtained data support the notion that PEVs do not influence in vitro lymphocyte proliferation, differentiation and cytokine production in a canine model.

Mesenchymal Stem Cell-Derived Extracellular Vesicles and Their Therapeutic Use in Central Nervous System Demyelinating Disorders

Autoimmune demyelinating diseases-including multiple sclerosis, neuromyelitis optica spectrum disorder, anti-myelin oligodendrocyte glycoprotein-associated disease, acute disseminated encephalomyelitis, and glial fibrillary acidic protein (GFAP)-associated meningoencephalomyelitis-are a heterogeneous group of diseases even though their common pathology is characterized by neuroinflammation, loss of myelin, and reactive astrogliosis. The lack of safe pharmacological therapies has purported the notion that cell-based treatments could be introduced to cure these patients. Among stem cells, mesenchymal stem cells (MSCs), obtained from various sources, are considered to be the ones with more interesting features in the context of demyelinating disorders, given that their secretome is fully equipped with an array of anti-inflammatory and neuroprotective molecules, such as mRNAs, miRNAs, lipids, and proteins with multiple functions. In this review, we discuss the potential of cell-free therapeutics utilizing MSC secretome-derived extracellular vesicles-and in particular exosomes-in the treatment of autoimmune demyelinating diseases, and provide an outlook for studies of their future applications.

Synergy of Human Platelet-Derived Extracellular Vesicles with Secretome Proteins Promotes Regenerative Functions

Platelet-rich plasma is a promising regenerative therapeutic with controversial efficacy. We and others have previously demonstrated regenerative functions of human platelet lysate (HPL) as an alternative platelet-derived product. Here we separated extracellular vesicles (EVs) from soluble factors of HPL to understand the mode of action during skin-organoid formation and immune modulation as model systems for tissue regeneration. HPL-EVs were isolated by tangential-flow filtration (TFF) and further purified by size-exclusion chromatography (SEC) separating EVs from (lipo)protein-enriched soluble fractions. We characterized samples by tunable resistive pulse sensing, western blot, tandem mass-tag proteomics and super-resolution microscopy. We evaluated EV function during angiogenesis, wound healing, organoid formation and immune modulation. We characterized EV enrichment by TFF and SEC according to MISEV2018 guidelines. Proteomics showed three major clusters of protein composition separating TSEC-EVs from HPL clustering with TFF soluble fractions and TFF-EVs clustering with TSEC soluble fractions, respectively. HPL-derived TFF-EVs promoted skin-organoid formation and inhibited T-cell proliferation more efficiently than TSEC-EVs or TSEC-soluble fractions. Recombining TSEC-EVs with TSEC soluble fractions re-capitulated TFF-EV effects. Zeta potential and super-resolution imaging further evidenced protein corona formation on TFF-EVs. Corona depletion on SEC-EVs could be artificially reconstituted by TSEC late fraction add-back. In contrast to synthetic nanoparticles, which commonly experience reduced function after corona formation, the corona-bearing EVs displayed improved functionality. We conclude that permissive isolation technology, such as TFF, and better understanding of the mechanism of EV corona function are required to realize the complete potential of platelet-based regenerative therapies.

Small Extracellular Vesicles Derived from Human Chorionic MSCs as Modern Perspective towards Cell-Free Therapy

Mesenchymal stem cells (MSCs) are of great interest to scientists due to their application in cell therapy of many diseases, as well as regenerative medicine and tissue engineering. Recently, there has been growing evidence surrounding the research based on extracellular vesicles (EVs), especially small EVs (sEVs)/exosomes derived from MSCs. EVs/exosomes can be secreted by almost all cell types and various types of EVs show multiple functions. In addition, MSCs-derived exosomes have similar characteristics and biological activities to MSCs and their therapeutic applications are considered as a safe strategy in cell-free therapy. The aim of this study was the characterization of MSCs isolated from the chorion (CHo-MSCs) of human full-term placenta, as well as the isolation and analysis of small EVs obtained from these cells. Accordingly, in this study, the ability of small EVs' uptake is indicated by synovial fibroblasts, osteoblasts and periosteum-derived MSCs. Improvement in the understanding of the structure, characteristics, mechanism of action and potential application of MSCs-derived small EVs can provide new insight into improved therapeutic strategies.