In vitro immunotoxicity assessment of culture-derived extracellular vesicles in human monocytes

A comprehensive evaluation of stability and safety for HEK293F-derived extracellular vesicles as promising drug delivery vehicles

HEK293F-derived extracellular vesicles (HEK293F-EVs) have great potential as next-generation drug delivery vehicles. A comprehensive understanding of their batch stability and in vivo safety is prerequisite for clinical translation. HEK293F-EVs were purified using ultracentrifugation combined with size exclusion chromatography, and their physicochemical properties, such as morphology, size distribution, and biomarkers, were thoroughly characterized. Raman spectroscopy and multi-omics analyses were employed to elaborate their molecular composition. Blood kinetics and biodistribution were assessed via IVIS spectrum imaging. Additionally, long-term in vivo safety was evaluated following multiple-dose administration through hematology, serum biochemistry, cytokine/chemokine profiling, and histopathology. HEK293F-EVs exhibited stable yields, purity, physicochemical properties (morphology, size, zeta potential, and marker proteins), and chemical composition across different cell passages (P10, P20, P30), with no significant variations. Content profiling, including protein, miRNA, metabolite, and lipid, confirmed consistent molecular stability across five production batches. GO, Reactome, and KEGG analyses revealed minimal enrichment in pathways related to acute immune response or cytotoxicity. Blood kinetics studies indicated rapid clearance of HEK293F-EVs from circulation, though slightly slower than PEG-Liposomes. Organ biodistribution was comparable between HEK293F-EVs and PEG-Liposomes, with HEK293F-EVs potentially having longer retention times. Importantly, HEK293F-EVs exhibited a favorable preclinical long-term safety profile, showing low immunogenicity and fewer tissue lesions compared to PEG-Liposomes. Our study demonstrates that HEK293F-EVs maintain stable physicochemical characteristics and compositions across batches and possess a superior safety profile, suggesting their significant potential as a safe and reliable drug delivery platform for clinical applications.

Effects of combined cyclosporin and azithromycin treatment on human mononuclear cells under lipopolysaccharide challenge

Objective

To evaluate the combined effects of azithromycin and varying concentrations of cyclosporin on peripheral blood mononuclear cells (PBMCs) under lipopolysaccharide (LPS) stimulation.

Materials and methods

PBMCs were isolated from four healthy donors and treated with cyclosporin at concentrations of (50, 200, and 1,000 ng/ml) either alone or in combination with azithromycin (0.4 µg/ml), with and without 100 ng ml LPS derived from Porphyromonas gingivalis. Total cell count, cell viability, and lactate dehydrogenase (LDH) activity were assessed at day 1 and 3. While the inflammatory mediators, including IL-6, IL-1β, IL-18, and IgA levels were assessed by ELISA at day 3. Statistical analysis included two-way ANOVA to analyze the effects of the drugs and the presence of LPS (the two independent variables), followed by Tukey's HSD post-hoc test. Multiple linear regression models evaluating treatment effects, LPS exposure, and time points, with assessment of two-way interactions. Models were adjusted for relevant covariates and verified for statistical assumptions, with significance set at p < 0.05.

Results

Lower cyclosporin concentrations (50 and 200 ng/ml) combined with azithromycin maintained higher cell counts and showed reduced cytotoxicity compared to 1,000 ng/ml under LPS exposure. The 200 ng/ml cyclosporin-azithromycin combination demonstrated optimal results, reducing IL-6 and IL-1β levels while maintaining cell viability. Higher concentrations elevated IgA levels, particularly with LPS stimulation, suggesting enhanced immune response modulation.

Conclusion

The combination of azithromycin with moderate cyclosporin concentrations (200 ng/ml) provides optimal immunomodulatory effects while maintaining cell viability. Higher cyclosporin doses (1,000 ng/ml) showed increased cytotoxicity despite enhanced immunomodulation.

Scalable production and purification of engineered ARRDC1-mediated microvesicles in a HEK293 suspension cell system

Engineering of human ARRDC1-mediated microvesicles (ARMMs) as non-viral vehicles for delivery of gene therapies bears the potential to enable novel therapeutic paradigms. We evaluated two scalable strategies to generate ARMMs loaded with protein cargo, by transient transfection or stable cell line-based production. The upstream ARMMs production processes utilized a suspension-adapted HEK293-derived line, termed 5B8. 5B8 cells yielded robust production of ARMMs after transient transfection with the ARMMs loading construct or using a stable cell line containing a transgene that encodes the ARMMs loading cassette, in shake flasks or a stirred tank bioreactor, respectively. ARMMs were purified by ultracentrifugation (small scale) or a combination of TFF and AEX (scalable production). Both purification methods produced comparable ARMMs, in terms of size and payload incorporation. Single particle analysis showed approximately 50% were payload-containing ARMMs. Additionally, an in vivo study was conducted in mice to investigate the half-life and biodistribution of ARMMs administered intravenously. ARMMs showed rapid biodistribution predominantly to the spleen and liver and, to a lesser extent, kidneys, and lungs. The half-life of ARMMs in plasma was 6 ± 0.4 min. Altogether, this work advances knowledge on scale-up of engineered cell-derived vesicles for future in vivo delivery of therapeutic molecules.

Enhancing precision targeting of ovarian cancer tumor cells in vivo through extracellular vesicle engineering

Extracellular vesicles (EVs) function as natural mediators of intercellular communication, secreted by cells to facilitate cell-cell signaling. Due to their low toxicity, immunogenicity, biodegradability, and potential to encapsulate therapeutic drugs, EVs hold significant therapeutic promise. Nevertheless, their limited targeting ability often diminishes their therapeutic impact. Therefore, enhancing EVs by incorporating targeting units onto their membranes could bolster their targeting capabilities, enabling them to accumulate in specific cells and tissues. In this study, we engineered EVs to fuse ephrin-B2 with the EV membrane protein LAMP2b. This modification aimed to direct the engineered EVs toward the ephrin-B4 receptor expressed on the surface of ovarian cancer cells. The engineered EVs retained their inherent properties, including size, expression of EV membrane proteins, and morphology, upon isolation. In vitro experiments using real-time imaging revealed that EVs engineered with the ephrin-B2 ligand exhibited substantial internalization and uptake by ovarian cancer cells, in stark contrast to native EVs. In vivo, the engineered EVs carrying the ephrin-B2 ligand effectively targeted ovarian cancer cells, surpassing the targeting efficiency of control EVs. This innovative approach establishes a novel targeting system, enhancing the uptake of EVs by ovarian cancer cells. Our findings underscore the potential of using EVs to target cancer cells, thereby enhancing the effectiveness of anti-cancer therapies while minimizing off-target effects and toxicity in normal cells and organs.

Ligand-displaying-exosomes using RNA nanotechnology for targeted delivery of multi-specific drugs for liver cancer regression

Liver cancer such as hepatocellular carcinoma (HCC) poorly responds to chemotherapeutics as there are no effective means to deliver the drugs to liver cancer. Here we report GalNAc decorated exosomes as cargo for targeted delivery of Paclitaxel (PTX) and miR122 to liver tumors as an effective means to inhibit the HCC. Exosomes (Exos) are nanosized extracellular vesicles that deliver a payload to cancer cells effectively. GalNAc provides Exos targeting ability by binding to the asialoglycoprotein-receptor (ASGP-R) overexpressed on the liver cancer cell surface. A 4-way junction (4WJ) RNA nanoparticle was constructed to harbor 24 copies of hydrophobic PTX and 1 copy of miR122. The 4WJ RNA-PTX complex was loaded into the Exos, and its surface was decorated with GalNAc using RNA nanotechnology to obtain specific targeting. The multi-specific Exos selectively bind and efficiently delivered the payload into the liver cancer cells and exhibited the highest cancer cell inhibition due to the multi-specific effect of miR122, PTX, GalNAc, and Exos. The same was reflected in mice xenograft studies, the liver cancer was efficiently inhibited after systemic injection of the multi-specific Exos. The required effective dose of chemical drugs carried by Exos was significantly reduced, indicating high efficiency and low toxicity. The multi-specific strategy demonstrates that Exos can serve as a natural cargo vehicle for the targeted delivery of anticancer therapeutics to treat difficult-to-treat cancers.

Tetrandrine ameliorates cognitive deficits and mitigates tau aggregation in cell and animal models of tauopathies

Background

Tauopathies are neurodegenerative diseases that are associated with the pathological accumulation of tau-containing tangles in the brain. Tauopathy can impair cognitive and motor functions and has been observed in Alzheimer’s disease (AD) and frontotemporal dementia (FTD). The aetiology of tauopathy remains mysterious; however, recent studies suggest that the autophagic-endolysosomal function plays an essential role in the degradation and transmission of pathological tau. We previously demonstrated that tetrandrine could ameliorate memory functions and clear amyloid plaques in transgenic AD mice by restoring autophagic-endolysosomal function. However, the efficacy of tetrandrine and the associated therapeutic mechanism in tauopathies have not been evaluated and elucidated.

Methods

Novel object recognition, fear conditioning and electrophysiology were used to evaluate the effects of tetrandrine on memory functions in transgenic tau mice. Western blotting and immunofluorescence staining were employed to determine the effect of tetrandrine on autophagy and tau clearance in vivo. Calcium (Ca²⁺) imaging and flow cytometry were used to delineate the role of pathological tau and tetrandrine in lysosomal Ca²⁺ and pH homeostasis. Biochemical BiFC fluorescence, Western blotting and immunofluorescence staining were used to evaluate degradation of hyperphosphorylated tau in vitro, whereas coculture of brain slices with isolated microglia was used to evaluate tau clearance ex vivo.

Results

We observed that tetrandrine treatment mitigated tau tangle development and corrected memory impairment in Thy1-hTau.P301S transgenic mice. Mechanistically, we showed that mutant tau expression disrupts lysosome pH by increasing two-pore channel 2 (TPC2)-mediated Ca²⁺ release, thereby contributing to lysosome alkalinization. Tetrandrine inhibits TPC2, thereby restoring the lysosomal pH, promotes tau degradation via autophagy, and ameliorates tau aggregation. Furthermore, in an ex vivo assay, we demonstrated that tetrandrine treatment promotes pathological tau clearance by microglia.

Conclusions

Together, these findings suggest that pathological tau disturbs endolysosomal homeostasis to impair tau clearance. This impairment results in a vicious cycle that accelerates disease pathogenesis. The success of tetrandrine in reducing tau aggregation suggests first, that tetrandrine could be an effective drug for tauopathies and second, that rescuing lysosomal Ca²⁺ homeostasis, thereby restoring ALP function, could be an effective general strategy for the development of novel therapies for tauopathies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00871-6.

Characteristics of Extracellular Vesicles and Preclinical Testing Considerations Prior to Clinical Applications

Cell therapy products have significant limitations, such as storage instability, difficulties with transportation, and toxicity issues such as tumorigenicity and immunogenicity. Extracellular vesicles (EVs) secreted from cells show potential for therapeutic agent development. EVs have not been widely examined as investigational drugs, and non-clinical studies for the clinical approval of EV therapeutic agents are challenging. EVs contain various materials, such as DNA, cellular RNA, cytokines, chemokines, and microRNAs, but do not proliferate or divide like cells, thus avoiding safety concerns related to tumorigenicity. However, the constituents of EVs may induce the proliferation of normal cells; therefore, the suitability of vesicles should be verified through non-clinical safety evaluations. In this review, the findings of non-clinical studies on EVs are summarized. We describe non-clinical toxicity studies of EVs, which should be useful for researchers who aim to develop these vesicles into therapeutic agents. A new method for evaluating the immunotoxicity and tumorigenicity of EVs should also be developed.

Nonviral Delivery Systems of mRNA Vaccines for Cancer Gene Therapy

In recent years, the use of messenger RNA (mRNA) in the fields of gene therapy, immunotherapy, and stem cell biomedicine has received extensive attention. With the development of scientific technology, mRNA applications for tumor treatment have matured. Since the SARS-CoV-2 infection outbreak in 2019, the development of engineered mRNA and mRNA vaccines has accelerated rapidly. mRNA is easy to produce, scalable, modifiable, and not integrated into the host genome, showing tremendous potential for cancer gene therapy and immunotherapy when used in combination with traditional strategies. The core mechanism of mRNA therapy is vehicle-based delivery of in vitro transcribed mRNA (IVT mRNA), which is large, negatively charged, and easily degradable, into the cytoplasm and subsequent expression of the corresponding proteins. However, effectively delivering mRNA into cells and successfully activating the immune response are the keys to the clinical transformation of mRNA therapy. In this review, we focus on nonviral nanodelivery systems of mRNA vaccines used for cancer gene therapy and immunotherapy.

Exosomes in serum‑free cultures of THP‑1 macrophages infected with Mycobacterium tuberculosis

It has been shown from the isolation and characterization of exosomes from cell culture media supplemented with fetal bovine serum that both their quality and purity are affected. The high abundance of serum proteins, including bovine cell derived exosomes, is also a potential source of contaminants, which may result in appreciable yields of impure exosomes, thereby leading to artifacts. Isolation and characterization of exosomes from cells maintained under serum-free conditions should therefore ensure the high quality necessary for medical applications. To meet this end, the present study aimed to characterize exosomes released from THP-1 macrophages cultured in serum-free, ultra-centrifuged medium upon infection with the human pathogen Mycobacterium tuberculosis (Mtb). Macrophages differentiated from the human cell line THP-1 were infected at a multiplicity of infection (MOI) of 5. Macrophages were cultivated in CellGenix^® GMP DC serum-free ultra-centrifuged medium for 4, 24 and 48 h at 37°C in a humidified atmosphere with 5% CO₂. Total exosome isolation reagent was used to extract the exosomes from the cell culture supernatants of naïve and Mtb-infected THP-1 macrophages. The size and purity of the exosomes isolated were subsequently assessed by various methods, including nanoparticle tracking analysis, flow cytometry, MACSPlex exosome analysis, and western blotting. The serum-free, ultra-centrifuged medium was found to support the proliferation of the THP-1 cells successfully. The nanoparticle tracking analysis data revealed that the majority of the isolated particles were within the size range of exosomes (i.e., 30–150 nM). The MACSPlex exosome analysis confirmed the expression of the exosomal markers, CD9, CD63 and CD81. Furthermore, western blot analysis of the isolated exosomes indicated the presence of CD9, CD63, CD81 and lysosomal associated membrane protein-1 (LAMP-1), and also confirmed the absence of Mtb proteins. Taken together, these data provide evidence that serum-free, ultra-centrifuged CellGenix^® GMP DC medium is suitable for application in exosome research, and may significantly advance such studies. Therefore, the use of serum-free medium for exosome isolation purposes could offer considerable advantages, and constitute a significant improvement in the growing field of extracellular vesicle research. The use of more sensitive methods represents an advance that will enable researchers to rule out the presence of Mtb pathogenic proteins in exosomes isolated from infected serum-free cell cultures.

Exosomes for mRNA delivery: a novel biotherapeutic strategy with hurdles and hope

Over the past decade, therapeutic messenger RNAs (mRNAs) have emerged as a highly promising new class of drugs for protein replacement therapies. Due to the recent developments, the incorporation of modified nucleotides in synthetic mRNAs can lead to maximizing protein expression and reducing adverse immunogenicity. Despite these stunning improvements, mRNA therapy is limited by the need for the development of safe and efficient carriers to protect the mRNA integrity for in vivo applications. Recently, leading candidates for in vivo drug delivery vehicles are cell-derived exosomes, which have fewer immunogenic responses. In the current study, the key hurdles facing mRNA-based therapeutics, with an emphasis on recent strategies to overcoming its immunogenicity and instability, were highlighted. Then the immunogenicity and toxicity of exosomes derived from various cell sources were mentioned in detail. Finally, an overview of the recent strategies in using exosomes for mRNA delivery in the treatment of multiple diseases was stated.

Functional differences and similarities in activated peripheral blood mononuclear cells by lipopolysaccharide or phytohemagglutinin stimulation between human and cynomolgus monkeys

Background

The monkey is a primary species used in toxicological research. However, the failures of preclinical studies to predict a life-threatening “cytokine storm”, which, for instance, rapidly occurred in six healthy volunteers with the CD28 superagonist monoclonal antibody (mAb) TGN1412 in the first-in-human phase I clinical trial, have emphasized a need to clarify the differences between human and monkey immune systems.

Methods

In the present study, we analyzed and compared the lymphocyte proliferation, cytokine secretion, and gene expression profiles after phytohemagglutinin (PHA) and lipopolysaccharide (LPS) stimulation of peripheral blood mononuclear cells (PBMCs) from three healthy humans and cynomolgus monkeys (Macaca fascicularis).

Results

The results derived from comparison with the corresponding control groups showed that PHA in humans induced a stronger proliferation and wider range of cytokine secretion, along with a greater number of differently expressed genes (DEGs), than when PHA was applied in cynomolgus monkeys. The significant upregulation of genes involved in the mitotic cell cycle, including cyclin B2, TOP2A, TYMS, and CEP55, was observed in human PBMCs with PHA stimulation, while only infrequent or slight upregulation occurred in cynomolgus monkey PBMCs, which may be one of the reasons for a stronger response to PHA in humans. In contrast to PHA, LPS in both species induced a similar proliferation ratio, cytokine profile, and DEG count, suggesting that human and cynomolgus monkeys have a similar response intensity for innate immune responses. Furthermore, 38 and 20 overlapped genes under PHA and LPS stimulation, respectively, were found in both species. These overlapped DEGs were associated with the same biological functions, including DNA replication, mitosis, immune response, chemotaxis, and inflammatory response. Thus, these results might reflect the highly conserved signatures of immune responses to PHA/LPS stimulation across the primates. Moreover, there were some differences in antigen processing and presentation, and the interferon gamma (INF-γ)–mediated signaling pathway in these species detected by gene expression profile study.

Conclusions

In conclusion, this is the first study to compare data on the responses of PBMCs to PHA and LPS in humans versus cynomolgus monkeys, and these findings may provide crucial insights into translating non-human primate (NHP) studies into human trials.

Exosomes derived from HEK293T cells interact in an efficient and noninvasive manner with mammalian sperm in vitro

Aim: To investigate exosomes as a noninvasive delivery tool for mammalian sperm. Materials & Methods: Exosomes were isolated from HEK293T cells and co-incubated with boar sperm in vitro. Results: Internalized exosomes were detected within 10 min of co-incubation. Computer-assisted sperm analysis and flow cytometry demonstrated that even after 5-h of exposure to exosomes, there were no significant deleterious effects with regard to sperm motility, viability, membrane integrity and mitochondrial membrane potential (p > 0.05), thus indicating that exosomes did not interfere with basic sperm function. Conclusion: HEK293T-derived exosomes interacted with boar sperm without affecting sperm function. Exosomes represent a versatile and promising research tool for studying sperm biology and provide new options for the diagnosis and treatment of male infertility.

New Therapeutic Strategies for Osteoarthritis by Targeting Sialic Acid Receptors

Osteoarthritis (OA) is the most common degenerative joint disease characterized by articular cartilage degradation and joint degeneration. The articular cartilage is mainly formed by chondrocytes and a collagen-proteoglycan extracellular matrix that contains high levels of glycosylated proteins. It was reported that the shift from glycoproteins containing α-2,6-linked sialic acids to those that contain α-2,3 was associated with the onset of common types of arthritis. However, the pathophysiology of α-2,3-sialylation in cartilage has not been yet elucidated. We show that cartilage from osteoarthritic patients expresses high levels of the α-2,3-sialylated transmembrane mucin receptor, known as podoplanin (PDPN). Additionally, the Maackia amurensis seed lectin (MASL), that can be utilized to target PDPN, attenuates the inflammatory response mediated by NF-kB activation in primary chondrocytes and protects human cartilage breakdown ex vivo and in an animal model of arthritis. These findings reveal that specific lectins targeting α-2,3-sialylated receptors on chondrocytes might effectively inhibit cartilage breakdown. We also present a computational 3D molecular model for this interaction. These findings provide mechanistic information on how a specific lectin could be used as a novel therapy to treat degenerative joint diseases such as osteoarthritis.

In vitro synergistic activity of erythromycin and nisin against clinical Group B Streptococcus isolates

AIMS

This study investigated the potential synergy between erythromycin and nisin against clinical Group B Streptococcus (GBS) strains.

METHODS AND RESULTS

The combination of erythromycin and nisin was examined for synergistic activity using checkerboard and time-kill assays against invasive and colonizing GBS strains. Additionally, the immunological effect of the antibiotic combination was investigated in vitro using human U937 cells and ELISA analysis. Checkerboard assays confirmed an additive effect when the antimicrobials were combined, while time-kill assays demonstrated a synergistic effect when antimicrobials were combined for invasive GBS isolates. Furthermore, a significantly lower TNF-alpha response (P < 0·05) was observed in U937 cells challenged with GBS when erythromycin and nisin were used in combination.

CONCLUSIONS

The results suggest that erythromycin and nisin can act synergistically to inhibit the growth of GBS.

SIGNIFICANCE AND IMPACT OF THE STUDY

Group B Streptococcus is the leading cause of invasive neonatal disease worldwide and is becoming increasingly more prevalent in adults. Resistance to some conventionally used antibiotics, such as erythromycin and clindamycin, continue to rise among GBS, indicating a need for alternative treatments. This study demonstrates the potential of an erythromycin-nisin combination for treatment of GBS infections and encourages further investigation of this treatment option.

Low active loading of cargo into engineered extracellular vesicles results in inefficient miRNA mimic delivery

Extracellular vesicles (EVs) hold great potential as novel systems for nucleic acid delivery due to their natural composition. Our goal was to load EVs with microRNA that are synthesized by the cells that produce the EVs. HEK293T cells were engineered to produce EVs expressing a lysosomal associated membrane, Lamp2a fusion protein. The gene encoding pre-miR-199a was inserted into an artificial intron of the Lamp2a fusion protein. The TAT peptide/HIV-1 transactivation response (TAR) RNA interacting peptide was exploited to enhance the EV loading of the pre-miR-199a containing a modified TAR RNA loop. Computational modeling demonstrated a stable interaction between the modified pre-miR-199a loop and TAT peptide. EMSA gel shift, recombinant Dicer processing and luciferase binding assays confirmed the binding, processing and functionality of the modified pre-miR-199a. The TAT-TAR interaction enhanced the loading of the miR-199a into EVs by 65-fold. Endogenously loaded EVs were ineffective at delivering active miR-199a-3p therapeutic to recipient SK-Hep1 cells. While the low degree of miRNA loading into EVs through this approach resulted in inefficient distribution of RNA cargo into recipient cells, the TAT TAR strategy to load miRNA into EVs may be valuable in other drug delivery approaches involving miRNA mimics or other hairpin containing RNAs.

Comprehensive toxicity and immunogenicity studies reveal minimal effects in mice following sustained dosing of extracellular vesicles derived from HEK293T cells

Extracellular vesicles (EVs) are under evaluation as therapeutics or as vehicles for drug delivery. Preclinical studies of EVs often use mice or other animal models to assess efficacy and disposition. However, as most EVs under evaluation are derived from human cells, they may elicit immune responses which may contribute to toxicities or enhanced EV clearance. Furthermore, EVs from different cell sources or EVs comprising various cargo may differ with respect to immunogenicity or toxicity. To assess EV-induced immune response and toxicity, we dosed C57BL/6 mice with EVs intravenously and intraperitoneally for 3 weeks. EVs were harvested from wild type or engineered HEK293T cells which were modified to produce EVs loaded with miR-199a-3p and chimeric proteins. Blood was collected to assess hematology, blood chemistry, and immune markers. Spleen cells were immunophenotyped, and tissues were harvested for gross necropsy and histopathological examination. No signs of toxicity were observed, and minimal evidence of changes in immune markers were noted in mice dosed with engineered, but not with wild type EVs. This study provides a framework for assessment of immunogenicity and toxicity that will be required as EVs from varying cell sources are tested within numerous animal models and eventually in humans.

Telocytes and Their Extracellular Vesicles-Evidence and Hypotheses

Entering the new millennium, nobody believed that there was the possibility of discovering a new cellular type. Nevertheless, telocytes (TCs) were described as a novel kind of interstitial cell. Ubiquitously distributed in the extracellular matrix of any tissue, TCs are regarded as cells with telopodes involved in intercellular communication by direct homo- and heterocellular junctions or by extracellular vesicle (EVs) release. Their discovery has aroused the interest of many research groups worldwide, and many researchers regard them as potentially regenerative cells. Given the experience of our laboratory, where these cells were first described, we review the evidence supporting the fact that TCs release EVs, and discuss alternative hypotheses about their future implications.