Exploring the performance of Escherichia coli outer membrane vesicles as a tool for vaccine development against Chagas disease

BACKGROUND Vaccine development is a laborious craftwork in which at least two main components must be defined: a highly immunogenic antigen and a suitable delivery method. Hence, the interplay of these elements could elicit the required immune response to cope with the targeted pathogen with a long-lasting protective capacity. OBJECTIVES Here we evaluate the properties of Escherichia coli spherical proteoliposomes - known as outer membrane vesicles (OMVs) - as particles with natural adjuvant capacities and as antigen-carrier structures to assemble an innovative prophylactic vaccine for Chagas disease. METHODS To achieve this, genetic manipulation was carried out on E. coli using an engineered plasmid containing the Tc24 Trypanosoma cruzi antigen. The goal was to induce the release of OMVs displaying the parasite protein on their surface. FINDINGS As a proof of principle, we observed that native OMVs - as well as those carrying the T. cruzi antigen - were able to trigger a slight, but functional humoral response at low immunization doses. Of note, compared to the non-immunized group, native OMVs-vaccinated animals survived the lethal challenge and showed minor parasitemia values, suggesting a possible involvement of innate trained immunity mechanism. MAIN CONCLUSION These results open the range for further research on the design of new carrier strategies focused on innate immunity activation as an additional immunization target and venture to seek for alternative forms in which OMVs could be used for optimizing vaccine development.

Challenges in estimating the encapsulation efficiency of proteins in polymersomes - Which is the best method?

Abstract Polymersomes are nanometric vesicles that can encapsulate large and hydrophilic biomolecules, such as proteins, in the aqueous core. Data in literature show large variation in encapsulation efficiency (%EE) values depending on the method used for calculation. We investigated different approaches (direct and indirect) to quantify the %EE of different proteins (catalase, bovine serum albumin-BSA, L-asparaginase and lysozyme) in Pluronic L-121 polymersomes. Direct methods allow quantification of the actual payload of the polymersomes and indirect methods are based on the quantification of the remaining non-encapsulated protein. The protein-loaded polymersomes produced presented approximately 152 nm of diameter (PDI ~ 0.4). Higher %EE values were obtained with the indirect method (up to 25%), attributed to partial entanglement of free protein in the polymersomes poly(Ethylene Glycol) corona. For the direct methods, vesicles were disrupted with chloroform or proteins precipitated with solvents. Reasonable agreement was found between the two protocols, with values up to 8%, 6%, 17.6% and 0.9% for catalase, BSA, L-asparaginase and lysozyme, respectively. We believe direct determination is the best alternative to quantify the %EE and the combination of both protocols would make results more reliable. Finally, no clear correlation was observed between protein size and encapsulation efficiency.

Recent Progress on Pharmaceutical Properties of Extracellular Vesicles from Mesenchymal Stem Cells--Review / 中国实验血液学杂志

Mesenchymal stem cells (MSCs) have been officially approved in many countries to treat graft-versus-host disease, autoimmune disorders and those associated with tissue regeneration after hematopoietic stem cell transplantation. Studies in recent years have confirmed that MSC acts mainly through paracrine mechanism, in which extracellular vesicles secreted by MSC (MSC-EV) play a central role. MSC-EV has overwhelming advantages over MSC itself in the setting of adverse effects in clinical application, indicating that MSC-EV might take the place of its parent cells to be a potentially therapeutic tool for "cell-free therapy". The pharmaceutical properties of MSC-EV largely depend upon the practical and optimal techniques including large-scale expansion of MSC, the modification of MSC based on the indications and the in vivo dynamic features of MSC-EV, and the methods for preparing and harvesting large amounts of MSC-EV. The recent progresses on the issues above will be briefly reviewed.

Therapeutic effect of small extracellular vesicles derived from mesenchymal stem cells on retinal light injury and its mechanism / 中华实验眼科杂志

Objective:To investigate the effect of small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) in mouse model of retinal light injury and the possible mechanism.Methods:Human umbilical cord derived MSCs were identified by flow cytometry.Supernatants of passage 3-5 MSCs were collected.sEVs were harvested by ultracentrifugation and were identified by transmission electron microscopy.Sixty-five healthy female SPF-grade BALB/c mice aged 8-10 weeks were randomly divided into normal group (17 mice), phosphate buffered saline (PBS) group (24 mice) and sEVs group (24 mice). Mice in PBS and sEVs groups were intravitreally injected with 2 μl of PBS and sEVs, respectively, and were exposed to 930 lx blue light for 6 hours.No intervention was administered to the normal group.Three days after lighting, mice retinal structure was observed by hematoxylin-eosin staining.Apoptotic retinal cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). Retinal function was tested by electroretinogram.Differentially expressed mRNAs between PBS group and sEVs group were assayed by mRNA transcriptome sequencing and were analyzed through KEGG cluster analysis.The differential mRNAs were verified via real-time quantitative PCR.The study protocol was approved by the Animal Ethics Committee of Tianjin Medical University Eye Hospital (No.TJYY20201221035).Results:MSCs were positive for CD90 and CD105, negative for CD34 and CD45.The extracted MSC-sEVs showed a bilayer membrane vesicle with a diameter of 80-140 nm.Hematoxylin-eosin staining showed the arrangement of photoreceptor nuclei was disordered in outer nuclear layer in PBS group.The disorder of photoreceptor nuclei arrangement of sEVs group was slighter than that of PBS group.The apoptotic cell number of sEVs group was (14.60±4.04)/visual field, which was lower than (24.00±8.52)/visual field of PBS group, with a statistically significant difference ( t=2.37, P<0.05). The a-wave amplitude of sEVs group was (64.38±16.70)μV, which was higher than (16.78±6.37) μV of PBS group, showing a statistically significant difference ( P<0.05). The b-wave amplitudes of PBS and sEVs groups were (132.40±39.41) μV and (154.86±34.08) μV, respectively, which were lower than (338.38±27.41) μV of normal group, and the differences were statistically significant (both at P<0.05). A total of 110 differentially expressed mRNAs were detected.There were 109 downregulated mRNAs in sEVs group.Differentially expressed mRNAs were mainly inflammation- and immune-related pathways.PCR showed that the expression level of C-C motif chemokine ligand 2, C-C motif chemokine receptor 2, leukotriene B4, leukocyte Ig-like receptor A6 and interleukin-1β in sEVs group were significantly decreased in comparison with PBS group (all at P<0.05). Conclusions:MSC-sEVs can ameliorate blue light-induced retinal structural and functional damage.The protective effect may be achieved through inhibiting inflammatory response.

Progress of mesenchymal stem cells in the treatment of bronchopulmonary dysplasia / 国际儿科学杂志

Bronchopulmonary dysplasia(BPD) is a chronic lung disease in the premature infants, which is an important cause of poor prognosis in the premature infants.The pathogenesis of BPD involves a variety of prenatal and postnatal mechanisms affecting the development of immature lungs.The combined effect of BPD alters lung morphogenesis, disrupts capillary gas exchange in the alveoli, and leads to pathological and clinical features of BPD.The current clinical methods used to treat BPD are still difficult to improve its prognosis.Mesenchymal stem/stromal cell(MSC) is a promising and innovative therapy for the treatment of a wide range of diseases due to the ease of extraction, low immunogenicity, anti-inflammatory properties and regenerative ability.In recent years, many experimental and clinical studies have found and proved that mesenchymal stem cell transplantation has a certain effect on BPD, so MSC may become the promising treatment for BPD in the future.However, the possibility that MSC may promote tumor growth, the presence of heterogeneous cell populations resulting in different efficacy, and ethical issues regarding the use of this treatment in humans make it a number of therapeutic challenges.This article reviews the mechanism of action and treatment of MSC in BPD, as well as the research progress in the treatment of BPD with MSC.

Research progress on kidney transplantation rejection associated with non-HLA antibody / 器官移植

Human leukocyte antigen (HLA) is a product encoded by HLA gene complex, which is located on the short arm of chromosome 6 and is the main target of alloimmunity. However, positive HLA antibody is not responsible for all kinds of rejections in kidney transplantation. Non-HLA antibody is the product of donor gene expression in allogeneic kidney transplantation. Intraoperative ischemia-reperfusion injury, the interaction between alloimmunity and autoimmunity and the mediation of extracellular vesicles may trigger immune system response and promote the production of non-HLA antibody. Multiple studies have demonstrated that non-HLA antibody is an important factor of inducing rejection and affecting the outcomes of kidney transplantation. Consequently, the types and formation mechanism of non-HLA antibody in kidney transplantation were reviewed, and research progress on kidney transplantation rejection associated with non-HLA antibody was summarized, aiming to provide reference for in-depth study of kidney transplantation rejection associated with non-HLA antibody.

Cross - species regulation and underlying mechanisms of parasite - derived non-coding RNAs: a review / 中国血吸虫病防治杂志

Parasite-derived non-coding RNAs (ncRNAs) not only contribute to life activities of parasites, and microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA) may generate a competitive endogenous RNA (ceRNA) regulatory network with host miRNAs and mRNAs via extracellular vesicles, thereby participating in infection and pathogenic processes. This article presents an overview of characterizing ncRNAs derived from parasites and the cross-species regulatory role of parasite-derived ncRNAs in host gene expression and its underlying mechanisms.

Construction and optimization of a novel plasma membrane model for membrane affinity assay based on polydiacetylene vesicles / 药学学报

Most drugs need to interact with cell membrane to reach the biological target, so that membrane affinity assay is an important early screening step in drug discovery. However, at present, the traditional oil-water distribution method is still used, a new, simple and accurate method for membrane affinity assay is urgently needed. In this study, according to the colorimetric principle, a new assay model based on polydiacetylene vesicles was optimized through a series of experiments including different concentrations of vesicle solution, temperature, or pH reaction environment. On this basis, tetracaine hydrochloride, 2-methylimidazole and histamine were used as model drugs to measure the membrane affinity constants and verify the between-batch precision of the optimized assay model (relative standard deviation less than 5%). In addition, polydiacetylene vesicles were stable for up to 180 days, demonstrating the potential application of the assay model. This strategy is simple, stable, reliable, with high reproducibility, low cost and easy to promote, which provided a new tool and a new direction for the high-throughput assay of membrane affinity.

Research advances on extracellular vesicles-based regulation by traditional Chinese medicines and the relationship with TCM "Qi" / 药学学报

Extracellular vesicles (EVs) are an important type of active microvesicles. EVs encapsulate and transfer functional substances such as miRNAs, transcription factors and proteins, which are important vectors for cell communication and organ dialogue. In recent years, studies have shown that quite a number of Chinese medicinal herbs have the pharmacological effect of regulating EVs, and play a unique trans-organ and remote role in the treatment of diseases. Some Chinese medicinal herbs also contain plant-derived EVs themselves, which can be directly involved in the treatment of diseases. As one of the core theories of raditional Chinese medicines (TCM), Qi plays a variety of important roles in the physiological and pathological processes of human body and pharmacology. However, the scientific connotation of Qi′s role and the potential material carrier are still unclear. The latest research suggests that the effect of EVs is potentially related to that of Qi. Therefore, this paper reviews the effect of Qi nourishing Chinese medicinal herbs in regulating EVs in the treatment of cardiovascular diseases, nervous system diseases, liver diseases, renal diseases, malignant tumors and other diseases in recent years. EVs may play an important role in the pharmacological effect of some Chinese medicinal herbs in the treatment of diseases as an intermediary substance. EVs have the characteristics of long-distance transportation, which is consistent with the movement of Qi in TCM. EVs carry a variety of functional molecules, which is consistent with the function of Qi. As the potential material basis of Qi in TCM, the function of EVs is worth further study.

Brain endothelial cell-derived extracellular vesicles with a mitochondria-targeting photosensitizer effectively treat glioblastoma by hijacking the blood‒brain barrier

Glioblastoma (GBM) is the most aggressive malignant brain tumor and has a high mortality rate. Photodynamic therapy (PDT) has emerged as a promising approach for the treatment of malignant brain tumors. However, the use of PDT for the treatment of GBM has been limited by its low blood‒brain barrier (BBB) permeability and lack of cancer-targeting ability. Herein, brain endothelial cell-derived extracellular vesicles (bEVs) were used as a biocompatible nanoplatform to transport photosensitizers into brain tumors across the BBB. To enhance PDT efficacy, the photosensitizer chlorin e6 (Ce6) was linked to mitochondria-targeting triphenylphosphonium (TPP) and entrapped into bEVs. TPP-conjugated Ce6 (TPP-Ce6) selectively accumulated in the mitochondria, which rendered brain tumor cells more susceptible to reactive oxygen species-induced apoptosis under light irradiation. Moreover, the encapsulation of TPP-Ce6 into bEVs markedly improved the aqueous stability and cellular internalization of TPP-Ce6, leading to significantly enhanced PDT efficacy in U87MG GBM cells. An in vivo biodistribution study using orthotopic GBM-xenografted mice showed that bEVs containing TPP-Ce6 [bEV(TPP-Ce6)] substantially accumulated in brain tumors after BBB penetration via transferrin receptor-mediated transcytosis. As such, bEV(TPP-Ce6)-mediated PDT considerably inhibited the growth of GBM without causing adverse systemic toxicity, suggesting that mitochondria are an effective target for photodynamic GBM therapy.

Extracellular vesicle-carried GTF2I from mesenchymal stem cells promotes the expression of tumor-suppressive FAT1 and inhibits stemness maintenance in thyroid carcinoma / 医学前沿

Through bioinformatics predictions, we identified that GTF2I and FAT1 were downregulated in thyroid carcinoma (TC). Further, Pearson's correlation coefficient revealed a positive correlation between GTF2I expression and FAT1 expression. Therefore, we selected them for this present study, where the effects of bone marrow mesenchymal stem cell-derived EVs (BMSDs-EVs) enriched with GTF2I were evaluated on the epithelial-to-mesenchymal transition (EMT) and stemness maintenance in TC. The under-expression of GTF2I and FAT1 was validated in TC cell lines. Ectopically expressed GTF2I and FAT1 were found to augment malignant phenotypes of TC cells, EMT, and stemness maintenance. Mechanistic studies revealed that GTF2I bound to the promoter region of FAT1 and consequently upregulated its expression. MSC-EVs could shuttle GTF2I into TPC-1 cells, where GTF2I inhibited TC malignant phenotypes, EMT, and stemness maintenance by increasing the expression of FAT1 and facilitating the FAT1-mediated CDK4/FOXM1 downregulation. In vivo experiments confirmed that silencing of GTF2I accelerated tumor growth in nude mice. Taken together, our work suggests that GTF2I transferred by MSC-EVs confer antioncogenic effects through the FAT1/CDK4/FOXM1 axis and may be used as a promising biomarker for TC treatment.

Physiological Roles of β-amyloid in Regulating Synaptic Function: Implications for AD Pathophysiology / 神经科学通报·英文版

The physiological functions of endogenous amyloid-β (Aβ), which plays important role in the pathology of Alzheimer's disease (AD), have not been paid enough attention. Here, we review the multiple physiological effects of Aβ, particularly in regulating synaptic transmission, and the possible mechanisms, in order to decipher the real characters of Aβ under both physiological and pathological conditions. Some worthy studies have shown that the deprivation of endogenous Aβ gives rise to synaptic dysfunction and cognitive deficiency, while the moderate elevation of this peptide enhances long term potentiation and leads to neuronal hyperexcitability. In this review, we provide a new view for understanding the role of Aβ in AD pathophysiology from the perspective of physiological meaning.

Progress on the cell therapy strategy of mesenchymal stem cells / 口腔疾病防治

@#Cell therapy based on mesenchymal stem cells (MSCs) has been a hot research topic in recent years, including the traditional cell therapy strategy based on living cells and the new cell-free therapy strategy based on soluble proteins or bioactive molecules such as extracellular vesicles (EVs). At present, MSC-induced cells have mature functions and specific structures, and insitu transplantation combined with biomaterials or organic technology has greatly improved the settlement rate and function. On the other hand, as the large-scale culture technique and EVs separation technique evolve, it is possible to obtain a large number of pure EVs, and EVs are gradually becoming a hot spot of current research. An increasing number of studies have shown that the therapeutic effect of MSCs not only occurs by implantation and differentiation but also manifests as the paracrine effect of MSCs. In this review, we discuss the emerging outcomes of cell therapies and acellular therapies to alleviate these pathological conditions.

Potential value of mesenchymal stem cells and their derivatives in repairing donor liver / 器官移植

In recent years, organ transplantation has developed rapidly in China, whereas the proportion of supply and demand of organs for donation is severely unbalanced. To resolve the shortage of donor livers, repairing extended criteria donor liver and improving the quality of donor liver are critical research directions. Mesenchymal stem cell (MSC) is a category of stem cells with self-renewal and differentiation potential, which possess the functions of immunomodulation and tissue repair. The derivatives of MSC have the advantages of low immunogenicity and high biocompatibility, which have been widely applied in the treatment of multiple diseases. In this article, research progress on the role of MSC, exosomes and extracellular vesicles in alleviating liver steatosis, repairing ischemia-reperfusion injury and promoting the regeneration of small-for-size liver allograft was reviewed, and the feasibility and safety of MSC and the derivatives in repairing donor liver were summarized, aiming provide novel ideas for repairing marginal donor liver and enhancing the quality of liver allograft.

Feasibility of outer membrane protein C as a protein presenting platform targeting antigen to surface of outer membrane vesicle / 中国生物制品学杂志

@#Abstract：Objective To investigate the feasibility of outer membrane protein C（OmpC）as a protein presenting platform targeting antigen to the surface of outer membrane vesicle（OMV）. Methods The recombinant expression plasmid containing ompC gene fragment and Staphylococcus aureus EsxA antigen gene（esxA gene）was constructed，transformed to competent E. coli BL21（DE3），inducedbyIPTG，andanalyzedforexpressedproductby 12%SDS⁃PAGE. Thetotalproteinofrecombinant strain OMV was analyzed by 12% SDS⁃PAGE，and the localization of fusion protein on the surface of OMV was detected by Western blot and Flow NanoAnalyzer. Results The recombinant expression plasmid containing ompC gene and esxA gene was constructed correctly as proved by sequencing. 12% SDS⁃PAGE showed that the fusion protein OmpC⁃EsxA had a relative molecular mass of about 57 000，which was consistent with the expected size，while the total protein of OMV showed multiple target protein bands，indicating that recombinant strain OMV was successfully extracted. The fusion protein OmpC⁃ EsxA on the surface of recombinant strain OMV specifically bound to mouse antibody against His⁃Tag，and OMVs labeled with fluorescent antibody were detected by Flow NanoAnalyzer. Conclusion OmpC may be used as a protein presenting plat⁃ form to locate antigen to OMV surface，which was expected to be applied in the development of antigen presentation vaccine. Keywords：Outer membrane protein C（OmpC）；Protein presentation；Outer membrane vesicle（OMV）

Research progress on emerging biomarkers in kidney transplantation / 器官移植

The hosts could show complex and diverse immune responses to the allografts. Whether biomarkers can be employed to explain the complexity of graft immune responses and the degree of disease damage are of significance. Conventional biomarkers, such as estimated glomerular filtration rate and blood concenrtation of immunosuppressant, lack of sensitivity and specificity in accurately identifying between immune and non-immune renal allograft injuries. Although renal biopsy is the "gold standard" for the diagnosis of postoperative complications, it still has disadvantages, such as invasiveness and high price, etc. Emerging biomarkers have potential advantages in the non-invasive diagnosis of subclinical injury of renal allograft, prediction of treatment response and individualized adjustment of immunosuppressive regimen. In this article, emerging biomarkers including blood, urine and tissue biomarkers that have been applied and are expected to be applied in clinical practice in the field of kidney transplantation were reviewed, and the range of application and effect of these biomarkers were evaluated, aiming to promote appropriate and rational application of these promising emerging biomarkers in clinical practice.

Added value of shear-wave elastography in the prediction of extracapsular extension and seminal vesicle invasion before radical prostatectomy / 亚洲男科学杂志(英文版)

The purpose of this study was to analyze the value of transrectal shear-wave elastography (SWE) in combination with multivariable tools for predicting adverse pathological features before radical prostatectomy (RP). Preoperative clinicopathological variables, multiparametric magnetic resonance imaging (mp-MRI) manifestations, and the maximum elastic value of the prostate (Emax) on SWE were retrospectively collected. The accuracy of SWE for predicting adverse pathological features was evaluated based on postoperative pathology, and parameters with statistical significance were selected. The diagnostic performance of various models, including preoperative clinicopathological variables (model 1), preoperative clinicopathological variables + mp-MRI (model 2), and preoperative clinicopathological variables + mp-MRI + SWE (model 3), was evaluated with area under the receiver operator characteristic curve (AUC) analysis. Emax was significantly higher in prostate cancer with extracapsular extension (ECE) or seminal vesicle invasion (SVI) with both P < 0.001. The optimal cutoff Emax values for ECE and SVI were 60.45 kPa and 81.55 kPa, respectively. Inclusion of mp-MRI and SWE improved discrimination by clinical models for ECE (model 2 vs model 1, P = 0.031; model 3 vs model 1, P = 0.002; model 3 vs model 2, P = 0.018) and SVI (model 2 vs model 1, P = 0.147; model 3 vs model 1, P = 0.037; model 3 vs model 2, P = 0.134). SWE is valuable for identifying patients at high risk of adverse pathology.

Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances

Cellular nanovesicles which are referred to as cell-derived, nanosized lipid bilayer structures, have emerged as a promising platform for regulating immune responses. Owing to their outstanding advantages such as high biocompatibility, prominent structural stability, and high loading capacity, cellular nanovesicles are suitable for delivering various immunomodulatory molecules, such as small molecules, nucleic acids, peptides, and proteins. Immunomodulation induced by cellular nanovesicles has been exploited to modulate immune cell behaviors, which is considered as a novel cell-free immunotherapeutic strategy for the prevention and treatment of diverse diseases. Here we review emerging concepts and new advances in leveraging cellular nanovesicles to activate or suppress immune responses, with the aim to explicate their applications for immunomodulation. We overview the general considerations and principles for the design of engineered cellular nanovesicles with tailored immunomodulatory activities. We also discuss new advances in engineering cellular nanovesicles as immunotherapies for treating major diseases.

Research progress in role of exosomes exosomes in mental disorders / 中南大学学报(医学版)

Exosomes are a class of extracellular vesicles with a structure of lipid bilayer-membrane. In the central nervous system (CNS), exosomes can be secreted from both neurons and glial cells. Exosomes released into the extracellular matrix can freely cross the blood-brain barrier and function as crucial carriers of cellular communication and substance exchange in the CNS. Exosomes play a key role in the pathological process of mental disorders such as schizophrenia, depression, and bipolar disorder, and they have the potential to be used as a targeted carrier of antipsychotic medications. Exosomes are likely to become a new tool in the future to aid in the early prevention, accurate diagnosis, and effective treatment for people with mental disorders.

Research progress on vesicle-associated membrane protein 8 / 中国生物制品学杂志

@#Membrane fusion is essential for all life activities of eukaryotes and the fusion process requires the interaction of different vesicular transporters,which are highly conserved in eukaryotes,to coordinate specifically and facilitate the fusion of different biofilms. Vesicle associated membrane protein 8(VAMP8)mainly locates in vesicular as well as lysosomal membranes,and plays a vital role in the fusion of many different biofilms. This paper focused on the molecular structure,transcriptional regulation,post-translational modification and biological function of VAMP8 as well as the research progress on its correlation with human diseases,so as to provide new ideas for the treatment of related diseases and the development of effective therapeutics targeting VAMP8.