Biocompatibility of highly purified bovine milk-derived extracellular vesicles

The Therapeutic Potential of Milk Extracellular Vesicles on Colorectal Cancer

Colorectal cancer remains one of the leading prevalent cancers in the world and is the fourth most common cause of death from cancer. Unfortunately, the currently utilized chemotherapies fail in selectively targeting cancer cells and cause harm to healthy cells, which results in profound side effects. Researchers are focused on developing anti-cancer targeted medications, which is essential to making them safer, more effective, and more selective and to maximizing their therapeutic benefits. Milk-derived extracellular vesicles (EVs) from camels and cows have attracted much attention as a natural substitute product that effectively suppresses a wide range of tumor cells. This review sheds light on the biogenesis, methods of isolation, characterization, and molecular composition of milk EVs as well as the therapeutic potentials of milk EVs on colorectal cancer.

M1-derived extracellular vesicles enhance photodynamic therapy and promote immunological memory in preclinical models of colon cancer

Extracellular vesicles (EVs) are promising drug carriers of photosensitizers for photodynamic therapy (PDT) in cancer treatment, due to their ability to circulate in blood and enter cells efficiently. The therapeutic potential of EVs has been suggested to depend on the type and physiological state of their cell of origin. However, the effects of deriving EVs from various cells in different physiological states on their antitumor capacity are rarely evaluated. In the present study, we compared the antitumor efficacy of EV-mediated PDT by incorporating the photosensitizer Zinc Phthalocyanine (ZnPc) into EVs from multiple cells sources. ZnPc was incorporated by a direct incubation strategy into EVs derived from immune cells (M1-like macrophages and M2-like macrophages), cancer cells (B16F10 melanoma cancer cells) and external sources (milk). Our data show that all EVs are suitable carriers for ZnPc and enable efficient PDT in vitro in co-culture models and in vivo. We observed that EV-mediated PDT initiates immunogenic cell death through the release and exposure of damage associated molecular patterns (DAMPs) on cancer cells, which subsequently induced dendritic cell (DC) maturation. Importantly, of all ZnPc-EVs tested, in absence of light only M1-ZnPc displayed toxicity to MC38, but not to DC, in monoculture and in co-culture, indicating specificity for cancer over immune cells. In MC38 tumor-bearing mice, only M1-ZnPc induced a tumor growth delay compared to control in absence of light. Interestingly, M1- but not M2-mediated PDT, induced complete responses against MC38 tumors in murine models (100% versus 38% of cases, respectively), with survival of all animals up to at least 60 days post inoculation. Finally, we show that all cured animals are protected from a rechallenge with MC38 cells, suggesting the induction of immunological memory after EV-mediated PDT. Together, our data show the importance of the cell type from which the EVs are obtained and highlight the impact of the immunological state of these cells on the antitumor efficacy of EV-mediated PDT.

Exosome Mediated Cytosolic Cisplatin Delivery Through Clathrin-Independent Endocytosis and Enhanced Anti-cancer Effect via Avoiding Endosome Trapping in Cisplatin-Resistant Ovarian Cancer

BACKGROUND

Ovarian carcinoma is one of the most common gynecologic malignancies, cisplatin resistance has become a key obstacle to the successful treatment of ovarian cancer because ovarian carcinomas are liable to drug resistance. To find an effective drug carrier is an urgent need.

METHODS

Exosomes and loading-cisplatin exosomes are isolated using differential centrifugation and characterized by transmission, electron, nanoparticle tracking analysis. The anti-cancer effect of cisplatin was detected under the circumstance of delivered by exosomes or without exosomes in vitro and in vivo. Using proteome analysis and bioinformatics analysis, we further discovered the pathways in exosomes delivery process. We employed a con-focal immunofluorescence analysis, to evaluate the effects of milk-exosomes deliver the cisplatin via avoiding endosomal trapping.

RESULTS

Exosomes and exosome-cisplatin were characterized including size, typical markers including CD63, Alix and Tsg101. The anti-cancer effect of cisplatin was enhanced when delivered by exosome in vitro and in vivo. Mechanistic studies shown that exosomes deliver cisplatin mostly via clathrin-independent endocytosis pathway. Exosomes deliver cisplatin into cisplatin-resistant cancer cells clathrin-independent endocytosis and enhance the anti-cancer effect through avoiding endosome trapping.

CONCLUSION

Cisplatin could be delivered by exosome through clathrin-independent endocytosis, and could evade the endosome trapping, diffused in the cytosol evenly. Our study clarifies the mechanism of exosomes mediated drug delivery against resistant cancer, indicates that exosomes can be a potential nano-carrier for cisplatin against cisplatin resistant ovarian cancer, which validates and enriches the theory of intracellular exosome trafficking.

Potential of Colostrum-Derived Exosomes for Promoting Hair Regeneration Through the Transition From Telogen to Anagen Phase

Human hair dermal papillary (DP) cells comprising mesenchymal stem cells in hair follicles contribute critically to hair growth and cycle regulation. The transition of hair follicles from telogen to anagen phase is the key to regulating hair growth, which relies heavily on the activation of DP cells. In this paper, we suggested exosomes derived from bovine colostrum (milk exosomes, Milk-exo) as a new effective non-surgical therapy for hair loss. Results showed that Milk-exo promoted the proliferation of hair DP cells and rescued dihydrotestosterone (DHT, androgen hormones)-induced arrest of follicle development. Milk-exo also induced dorsal hair re-growth in mice at the level comparable to minoxidil treatment, without associated adverse effects such as skin rashes. Our data demonstrated that Milk-exo accelerated the hair cycle transition from telogen to anagen phase by activating the Wnt/β-catenin pathway. Interestingly, Milk-exo has been found to stably retain its original properties and efficacy for hair regeneration after freeze-drying and resuspension, which is considered critical to use it as a raw material applied in different types of alopecia medicines and treatments. Overall, this study highlights a great potential of an exosome from colostrum as a therapeutic modality for hair loss.

Exosomes as Emerging Drug Delivery and Diagnostic Modality for Breast Cancer: Recent Advances in Isolation and Application

Breast cancer (BC) is the most common type of malignancy which covers almost one-fourth of all the cancers diagnosed in women. Conventionally, chemo-, hormonal-, immune-, surgery, and radiotherapy are the clinically available therapies for BC. However, toxicity and other related adverse effects are still the major challenges. A variety of nano platforms have been reported to overcome these limitations, among them, exosomes provide a versatile platform not only for the diagnosis but also as a delivery vehicle for drugs. Exosomes are biological nanovesicles made up of a lipidic bilayer and known for cell-to-cell communication. Exosomes have been reported to be present in almost all bodily fluids, viz., blood, milk, urine, saliva, pancreatic juice, bile, peritoneal, and cerebrospinal fluid. Such characteristics of exosomes have attracted immense interest in cancer diagnosis and therapy. They can deliver bioactive moieties such as protein, lipids, hydrophilic as well as hydrophobic drugs, various RNAs to both distant and nearby recipient cells as well as have specific biological markers. By considering the growing interest of the scientific community in this field, we comprehensively compiled the information about the biogenesis of exosomes, various isolation methods, the drug loading techniques, and their diverse applications in breast cancer diagnosis and therapy along with ongoing clinical trials which will assist future scientific endeavors in a more organized direction.

Determining extracellular vesicles properties and miRNA cargo variability in bovine milk from healthy cows and cows undergoing subclinical mastitis

Background

Subclinical mastitis, the inflammation of the mammary gland lacking clinical symptoms, is one of the most prevalent and costly diseases in dairy farming worldwide. Milk microRNAs (miRNAs) encapsulated in extracellular vesicles (EVs) have been proposed as potential biomarkers of different mammary gland conditions, including subclinical mastitis. However, little is known about the robustness of EVs analysis regarding sampling time-point and natural infections. To estimate the reliability of EVs measurements in raw bovine milk, we first evaluated changes in EVs size and concentration using Tunable Resistive Pulse Sensing (TRPS) during three consecutive days of sampling. Then, we analysed daily differences in miRNA cargo using small RNA-seq. Finally, we compared milk EVs differences from naturally infected udder quarters with their healthy adjacent quarters and quarters from uninfected udders, respectively.

Results

We found that the milk EV miRNA cargo was very stable over the course of three days regardless of the health status of the quarter, and that infected quarters did not induce relevant changes in milk EVs of adjacent healthy quarters. Chronic subclinical mastitis induced changes in milk EV miRNA cargo, but neither in EVs size nor concentration. We observed that the changes in immunoregulatory miRNAs in quarters with chronic subclinical mastitis were cow-individual, however, the most upregulated miRNA was bta-miR-223-3p across all individuals.

Conclusions

Our results showed that the miRNA profile and particle size characteristics remained constant throughout consecutive days, suggesting that miRNAs packed in EVs are physiological state-specific. In addition, infected quarters were solely affected while adjacent healthy quarters remained unaffected. Finally, the cow-individual miRNA changes pointed towards infection-specific alterations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08377-z.

Milk-Derived Exosomes as Nanocarriers to Deliver Curcumin and Resveratrol in Breast Tissue and Enhance Their Anticancer Activity

Dietary (poly)phenols are extensively metabolized, limiting their anticancer activity. Exosomes (EXOs) are extracellular vesicles that could protect polyphenols from metabolism. Our objective was to compare the delivery to breast tissue and anticancer activity in breast cancer cell lines of free curcumin (CUR) and resveratrol (RSV) vs. their encapsulation in milk-derived EXOs (EXO-CUR and EXO-RSV). A kinetic breast tissue disposition was performed in rats. CUR and RSV were analyzed using UPLC-QTOF-MS and GC-MS, respectively. Antiproliferative activity was tested in MCF-7 and MDA-MB-231 breast cancer and MCF-10A non-tumorigenic cells. Cell cycle distribution, apoptosis, caspases activation, and endocytosis pathways were determined. CUR and RSV peaked in the mammary tissue (41 ± 15 and 300 ± 80 nM, respectively) 6 min after intravenous administration of EXO-CUR and EXO-RSV, but not with equivalent free polyphenol concentrations. Nanomolar EXO-CUR or EXO-RSV concentrations, but not free CUR or RSV, exerted a potent antiproliferative effect on cancer cells with no effect on normal cells. Significant (p < 0.05) cell cycle alteration and pro-apoptotic activity (via the mitochondrial pathway) were observed. EXO-CUR and EXO-RSV entered the cells primarily via clathrin-mediated endocytosis, avoiding ATP-binding cassette transporters (ABC). Milk EXOs protected CUR and RSV from metabolism and delivered both polyphenols to the mammary tissue at concentrations compatible with the fast and potent anticancer effects exerted in model cells. Milk EXOs enhanced the bioavailability and anticancer activity of CUR and RSV by acting as Trojan horses that escape from cancer cells’ ABC-mediated chemoresistance.

Bovine Milk-Derived Extracellular Vesicles Inhibit Catabolic and Inflammatory Processes in Cartilage from Osteoarthritis Patients

SCOPE

Data from the Osteoarthritis Initiative shows that females who drink milk regularly have less joint cartilage loss and OA progression, but the biologic mechanism is unclear. Bovine milk is a rich source of extracellular vesicles (EVs), which are small phospholipid bilayer bound structures that facilitate intercellular communication. In this study, the authors aim to evaluate whether these EVs may have the capacity to protect cartilage from osteoarthritis patients, ex vivo, by directly effecting chondrocytes.

METHODS AND RESULTS

Human cartilage explants are exposed to cow's milk-derived EVs (CMEVs), which results in reduced sulfated glycosaminoglycan release and inhibition of metalloproteinase-1 expression. Incubation of articular chondrocytes with CMEVs also effectively reduces expression of cartilage destructive enzymes (ADAMTS5, MMPs), which play key roles in the disease progression. In part, these findings are attributed to the presence of TGFβ on these vesicles, and in addition, a possible role is reserved for miR-148a, which is functionally transferred by CMEVs.

CONCLUSION

These findings highlight the therapeutic potential of local CMEV delivery in osteoarthritic joints, where inflammatory and catabolic mediators are responsible for joint pathology. CMEVs are carriers of both TGFβ and miR-148a, two essential regulators for maintaining chondrocyte homeostasis and protection against cartilage destruction.

RNA and Protein Delivery by Cell-Secreted and Bioengineered Extracellular Vesicles

Extracellular vesicles (EVs) are carriers of biological signals through export and delivery of RNAs and proteins. Of increasing interest is the use of EVs as a platform for delivery of biomolecules. Preclinical studies have effectively used EVs to treat a number of diseases. Uniquely, endogenous machinery within cells can be manipulated in order to produce desirable loading of cargo within secreted EVs. In order to inform the development of such approaches, an understanding of the cellular mechanisms by which cargo is sorted to EVs is required. Here, the current knowledge of cargo sorting within EVs is reviewed. Here is given an overview of recent bioengineering approaches that leverage these advances. Methods of externally manipulating EV cargo are also discussed. Finally, a perspective on the current challenges of EVs as a drug delivery platform is offered. It is proposed that standardized bioengineering methods for therapeutic EV preparation will be required to create a well-defined clinical product.

Liraglutide Loaded-Milk Exosomes Lower Blood Glucose when Given by Sublingual Route

Bovine milk is rich in extracellular vesicles (mEVs) which have been suggested as a possible drug delivery vehicle with oral bioavailability. As the digestive fluids contain many lipid- and protein-degrading enzymes, we explored whether mEVs given sublingually could be taken up systemically. mEVs were isolated using three different protocols, which were 120 nm in diameter and carried bovine CD81. Fluorescently stained mEVs given by sublingual route were detected in the circulation, whereas mEVs given by gavage were detected at 2-Log lower concentrations. As proof of the concept, we loaded mEVs with the antidiabetic drug Liraglutide (LRT-EV), which reduced blood glucose levels when given by the sublingual route but showed no efficacy via gavaging. This study suggests that mEV may be an efficient delivery vehicle for drugs that are not orally bioavailable, and LRT-loaded EVs have the potential as the next-generation drug delivery platform for the treatment of chronic diseases, including diabetes.

Drug Loading and Functional Efficacy of Cow, Buffalo, and Goat Milk-Derived Exosomes: A Comparative Study

Quite recently, milk exosomes have been recognized as efficient drug delivery systems owing to their biocompatibility and easy availability for scale-up technologies. However, there are no reports of comparative studies with regards to drug delivery by milk exosomes derived from different species. In this study, we isolated and characterized milk exosomes of cow, buffalo, and goat by various techniques and tried to understand their drug loading capacity and functional efficiency in HepG2, HCT116, and A549 cells by using doxorubicin. Doxorubicin was loaded to milk exosomes by three methods, that is, incubation, saponin treatment, and sonication. The isolated exosomes were found to be spherical with a size of <200 nm and displayed specific markers, namely, CD81, HSP70, HSC70, and miRNAs. Drug loading studies revealed that goat milk exosomes had the highest loading capacity across all three methods. Doxorubicin-encapsulated goat milk exosomes resulted in the inhibition of cell viability, with low IC₅₀ values in HepG2, HCT-116, and A549 cells. Doxorubicin-encapsulated goat exosomes displayed better IC₅₀ values than cow and buffalo milk-derived counterparts. In line with this, the ability of doxorubicin-encapsulated goat milk exosomes to induce apoptosis in HepG2 and HCT-116 cells was higher than that of cow and buffalo milk exosomes and free doxorubicin. Furthermore, unbound goat milk exosomes significantly reduced cell viability as compared to cow and buffalo milk exosomes. The transepithelial transport assay shows that doxorubicin-loaded milk exosomes transport doxorubicin efficiently as compared to free doxorubicin in vitro. Doxorubicin released from milk exosomes shows a biphasic release pattern, burst release followed by sustained release. These observations are important in light of the emerging importance of milk-derived exosomes as drug carriers to treat cancers.

Perspectives on Bovine Milk-Derived Extracellular Vesicles for Therapeutic Applications in Gut Health

Extracellular vesicles (EVs) are nanosized vesicles secreted from cells into the extracellular environment and are composed of a lipid bilayer that contains cargos with biological activity, such as lipids, proteins, mRNAs, and noncoding microRNAs (miRNAs). Due to their biological activity and their role in cell-to-cell communication, interest in EVs is rapidly increasing. Bovine milk is a food consumed by people of all ages around the world that contains not only a significant amount of nutrients but also EVs. Milk-derived EVs also exhibit biological activity similar to other source-derived EVs, and studies on bovine milk EVs have been conducted in various research fields regarding sufficient milk production. In particular, not only are the effects of milk EVs themselves being studied, but the possibility of using them as drug carriers or biomarkers is also being studied. In this review, the characteristics and cargo of milk EVs are summarized, as well as their uptake and stability, efficacy and biological effects as carriers, and future research directions are presented.

Design and Evaluation of Engineered Extracellular Vesicle (EV)-Based Targeting for EGFR-Overexpressing Tumor Cells Using Monobody Display

Background: Extracellular vesicles (EVs) are attracting interest as a new class of drug delivery vehicles due to their intrinsic nature of biomolecular transport in the body. We previously demonstrated that EV surface modification with tissue-specific molecules accomplished targeted EV-mediated DNA delivery. Methods: Here, we describe reliable methods for (i) generating EGFR tumor-targeting EVs via the display of high-affinity monobodies and (ii) in vitro measurement of EV binding using fluorescence and bioluminescence labeling. Monobodies are a well-suited class of small (10 kDa) non-antibody scaffolds derived from the human fibronectin type III (FN3) domain. Results: The recombinant protein consists of the EGFR-targeting monobody fused to the EV-binding domain of lactadherin (C1C2), enabling the monobody displayed on the surface of the EVs. In addition, the use of bioluminescence or fluorescence molecules on the EV surface allows for the assessment of EV binding to the target cells. Conclusions: In this paper, we describe methods of EV engineering to generate targeted delivery vehicles using monobodies that will have diverse applications to furnish future EV therapeutic development, including qualitative and quantitative in vitro evaluation for their binding capacity.

Assessing extracellular vesicles from bovine mammary gland epithelial cells cultured in FBS-free medium

Aim

Mammary gland extracellular vesicles (EVs) are found in both human and livestock milk. Our knowledge of the role of EVs in the mammary gland development, breast cancer and mastitis derives mainly from in vitro cell culture models. However, a commonly shared limitation is the use of fetal bovine serum (FBS) as a supplement, which naturally contains EVs. For this reason, the purpose of the study was to evaluate novel tools to investigate mammary gland EVs in vitro and in a FBS-free system.

Methods

Primary bovine mammary epithelial cells (pbMECs) and a mammary gland alveolar epithelial cell line (MAC-T) were cultured in a chemically defined EV-free medium. To find a reliable EV isolation protocol from a starting cell conditioned medium (10 mL), we compared eight different methodologies by combining ultracentrifugation (UC), chemical precipitation (CP), size exclusion chromatography (SEC), and ultrafiltration (UF).

Results

The medium formula sustained both pbMECs and MAC-T cell growth. Transmission electron microscopy revealed that we obtained EV-like particles in five out of eight protocols. The cleanest samples with the highest number of particles and detectable amounts of RNA were obtained by using UF-SEC-UC.

Conclusion

Our chemically defined, FBS-free medium sustains the growth of both pbMECs and MAC-T and allows the isolation of EVs that are free from any contamination by UF-SEC-UC. In conclusion, we propose a new culture system and EVs isolation protocols for further research on mammary epithelial EVs.

Extracellular vesicle separation from milk and infant milk formula using acid precipitation and ultracentrifugation

Separation of highly enriched extracellular vesicles (EVs) fractions from milk is desirable for quantification, cargo analysis, functional characterization, and investigation as delivery vehicles for nutrients and/or therapeutics. However, a rigorous, reproducible protocol is lacking. This protocol considers a crucial aspect typically overlooked, i.e., that caseins are of similar size to, but more abundant than, EVs in milk. Our protocol combines acid pre-treatment and gradient ultracentrifugation, producing EV-enriched fractions suitable for downstream orthogonal characterization approaches.

For complete details on the use and execution of this protocol, please refer to Mukhopadhya et al. (2021).

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Casein micelles or contaminant-free EVs are best for milk EV characterization

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Acid pre-treatment + gradient ultracentrifugation essential to obtain pure milk EV

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Disrupted and fewer EVs identified in infant milk formula (IMF) than in skim milk

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Notably lower signals of surface markers obtained from IMF EVs than skim milk EVs

Active cargo loading into extracellular vesicles: Highlights the heterogeneous encapsulation behaviour

Extracellular vesicles (EVs) have demonstrated unique advantages in serving as nanocarriers for drug delivery, yet the cargo encapsulation efficiency is far from expectation, especially for hydrophilic chemotherapeutic drugs. Besides, the intrinsic heterogeneity of EVs renders it difficult to evaluate drug encapsulation behaviour. Inspired by the active drug loading strategy of liposomal nanomedicines, here we report the development of a method, named "Sonication and Extrusion-assisted Active Loading" (SEAL), for effective and stable drug encapsulation of EVs. Using doxorubicin-loaded milk-derived EVs (Dox-mEVs) as the model system, sonication was applied to temporarily permeabilize the membrane, facilitating the influx of ammonium sulfate solution into the lumen to establish the transmembrane ion gradient essential for active loading. Along with extrusion to downsize large mEVs, homogenize particle size and reshape the nonspherical or multilamellar vesicles, SEAL showed around 10-fold enhancement of drug encapsulation efficiency compared with passive loading. Single-particle analysis by nano-flow cytometry was further employed to reveal the heterogeneous encapsulation behaviour of Dox-mEVs which would otherwise be overlooked by bulk-based approaches. Correlation analysis between doxorubicin auto-fluorescence and the fluorescence of a lipophilic dye DiD suggested that only the lipid-enclosed particles were actively loadable. Meanwhile, immunofluorescence analysis revealed that more than 85% of the casein positive particles was doxorubicin free. These findings further inspired the development of the lipid-probe- and immuno-mediated magnetic isolation techniques to selectively remove the contaminants of non-lipid enclosed particles and casein assemblies, respectively. Finally, the intracellular assessments confirmed the superior performance of SEAL-prepared mEV formulations, and demonstrated the impact of encapsulation heterogeneity on therapeutic outcome. The as-developed cargo-loading approach and nano-flow cytometry-based characterization method will provide an instructive insight in the development of EV-based delivery systems.

Biological Nanotherapeutics for Liver Disease

Extracellular vesicles (EVs) are a heterogeneous group of biological nano-sized vesicles that are released from cells and contribute to intercellular communication. Emerging knowledge about their biogenesis, composition, release, and uptake has resulted in broad interest in elucidating their potential roles in disease pathophysiology. The distinct biological properties of these biological nanoparticles emphasize several appealing advantages for potential therapeutic applications compared with the use of synthetic nanoparticles. When administered systemically, EVs are taken up and sequestered within the liver, further emphasizing opportunities for therapeutic use. Consequently, there is growing interest in their use for liver diseases. EVs can be used directly as therapeutics, and several studies have highlighted the intrinsic therapeutic properties of mesenchymal stem cell-derived EVs for chronic and acute liver diseases. Alternatively, EVs can be modified to facilitate their use for the delivery of therapeutic cargo. In this review, we discuss the cellular sources of EV, provide a concise overview of their potential use in diverse processes, and outline several promising applications for the use of EV-based therapeutics for liver diseases. The use of EV-based therapeutics provides a viable approach to target hepatic pathophysiology.

Engineering and loading therapeutic extracellular vesicles for clinical translation: A data reporting frame for comparability

Extracellular vesicles (EVs) have emerged as new drug delivery systems as well as a regenerative cell-free effectors going beyond academic research to reach industrial research and development (R&D). Many proof-of-concept studies are now published describing the delivery of drugs, nanoparticles or biologics among which nucleic acids, proteins, viruses, etc. Their main interests rely on their intrinsic biocompatibility, targeting capabilities and biological activities. The possibility of loading EVs with exogenous therapeutic drug/nanoparticles or imaging tracers opens up the perspectives to extend EV therapeutic properties and enable EV tracking. Clinical translation is still hampered by the difficulty to produce and load EVs with large scale, efficient and cGMP methods. In this review, we critically discuss important notions related to EV engineering and the methods available with a particular focus on technologies fitted for clinical translation. Besides, we provide a tentative data reporting frame in order to support comparability and standardization in the field.

Dietary bovine milk miRNAs transported in extracellular vesicles are partially stable during GI digestion, are bioavailable and reach target tissues but need a minimum dose to impact on gene expression

PURPOSE

Extracellular RNAs are unstable and rapidly degraded unless protected. Bovine-milk extracellular vesicles (EVs) confer protection to dietary miRNAs, although it remains unclear whether this importantly improves their chances of reaching host target cells to exert biological effects.

METHODS

Caco-2, HT-29, Hep-G2 and FHs-74 cell lines were exposed to natural/labelled milk EVs to evaluate cellular uptake. Five frequently reported human milk miRNAs (miR-146b-5p, miR-148a-3p, miR-30a-5p, miR-26a-5p, and miR-22-3p) were loaded into EVs. The intracellular concentration of each miRNA in cells was determined. In addition, an animal study giving an oral dose of loaded EVs in C57BL6/ mice were performed. Gene expression regulation was assessed by microarray analysis.

RESULTS

Digestive stability analysis showed high overall degradation of exogenous miRNAs, although EV-protected miRNAs better resisted gastrointestinal digestion compared to free miRNAs (tenfold higher levels). Importantly, orally delivered EV-loaded miRNAs reached host organs, including brain, in mice. However, no biological effect has been identified.

CONCLUSION

Milk EVs protect miRNAs from degradation and facilitate cellular uptake. miRNA concentration in EVs from bovine milk might be insufficient to produce gene modulation. Nevertheless, sizable amounts of exogenous miRNAs may be loaded into EVs, and orally delivered EV-loaded miRNAs can reach tissues in vivo, increasing the possibility of exerting biological effects. Further investigation is justified as this could have an impact in the field of nutrition and health (i.e., infant formulas elaboration).

Latest Trend of Milk Derived Exosomes: Cargos, Functions, and Applications

Exosomes are nanosized phospholipid bilayer vesicles released to the extracellular environment. Exosomes from various tissues or cells are being studied and there has been a growing interest in milk exosomes research due to their emerging role as messengers between cells and the fact that it can be produced in large quantities with rich source of milk. Milk derived exosomes (MDEs) contain lipids, microRNAs, proteins, mRNAs as well as DNA. Studies of exosome cargo have been conducted widely in many research areas, especially exosomal miRNAs. In this paper, we reviewed the current knowledge in isolation and identification, cargos, functions mainly in intestinal tract and immunity system of MDEs. Its application as drug carriers and diseases biomarker are also discussed. Furthermore, we also consider critical challenges of MDEs application and provide possible directions for future research.

Skimmed Bovine Milk-Derived Extracellular Vesicles Isolated via "Salting-Out": Characterizations and Potential Functions as Nanocarriers

Bovine milk-derived extracellular vesicles (BM-EVs) are recognized as promising nanoscale delivery vectors owing to their large availability. However, few isolation methods can achieve high purity and yield simultaneously. Therefore, we developed a novel and cost-effective procedure to separate BM-EVs via "salting-out." First, BM-EVs were isolated from skimmed milk using ammonium sulfate. The majority of BM-EVs were precipitated between 30 and 40% saturation and 34% had a relatively augmented purity. The separated BM-EVs showed a spherical shape with a diameter of 60-150 nm and expressed the marker proteins CD63, TSG101, and Hsp70. The purity and yield were comparable to the BM-EVs isolated via ultracentrifugation while ExoQuick failed to separate a relatively pure fraction of BM-EVs. The uptake of BM-EVs into endothelial cells was dose- and time-dependent without significant cytotoxicity. The levels of endothelial nitric oxide syntheses were regulated by BM-EVs loaded with icariside II and miRNA-155-5p, suggesting their functions as delivery vehicles. These findings have demonstrated that it is an efficient procedure to isolate BM-EVs via "salting-out," holding great promise toward therapeutic applications.

Extracellular Vesicles in Human Milk

Milk supports the growth and development of infants. An increasing number of mostly recent studies have demonstrated that milk contains a hitherto undescribed component called extracellular vesicles (EVs). This presents questions regarding why milk contains EVs and what their function is. Recently, we showed that EVs in human milk expose tissue factor, the protein that triggers coagulation or blood clotting, and that milk-derived EVs promote coagulation. Because bovine milk, which also contains EVs, completely lacks this coagulant activity, important differences are present in the biological functions of human milk-derived EVs between species. In this review, we will summarize the current knowledge regarding the presence and biochemical composition of milk EVs, their function(s) and potential clinical applications such as in probiotics, and the unique problems that milk EVs encounter in vivo, including survival of the gastrointestinal conditions encountered in the newborn. The main focus of this review will be human milk-derived EVs, but when available, we will also include information regarding non-human milk for comparison.

Bovine Milk Exosomes Alleviate Cardiac Fibrosis via Enhancing Angiogenesis In Vivo and In Vitro

Cardiac fibrosis is a difficult clinical puzzle without effective therapy. Exosomes play an important role in alleviating cardiac fibrosis via angiogenesis. This research aimed to assess the effect of bovine milk on cardiac fibrosis. The proangiogenic effect of bovine milk exosomes was analyzed both in isoproterenol (ISO)-induced cardiac fibrosis rats in vivo and in human umbilical vein endothelial cells (HUVECs) after oxygen and glucose deprivation (OGD) in vitro. Results indicated that bovine milk exosomes alleviated the extracellular matrix (ECM) deposition and enhanced the cardiac function in cardiac fibrosis rat. The proangiogenic growth factors were significantly enhanced in rats accepted bovine milk exosomes. Meanwhile, bovine milk exosomes ameliorated the motility, migration, and tube-forming ability of HUVECs after OGD in vitro. Bovine milk exosomes alleviate cardiac fibrosis and enhance cardiac function in cardiac fibrosis rats via enhancing angiogenesis. Bovine milk exosomes may represent a potential strategy for the treatment of cardiac fibrosis.

Insight into the Exosomal Membrane: From Viewpoints of Membrane Fluidity and Polarity

Numerous research studies have been done for exosomes, particularly focusing on membrane proteins and included nucleic acids, and the volume of the knowledge about the lipids in the exosomal membrane has been increasing. However, the dynamic property of the exosomal membrane is hardly studied. By employing milk exosome as an example, herein the exosomal membrane was characterized focusing on the membrane fluidity and polarity. The lipid composition and phase state of milk exosome (exosome from bovine milk) were estimated. The milk exosome contained enriched Chol (43.6 mol % in total lipid extracts), which made the membrane in the liquid-ordered (l_o) phase by interacting with phospholipids. To suggest a model of exosomal vesicle cargo, the liposome compositions that mimic milk exosome were studied: liposomes were made of cholesterol (Chol), milk sphingomyelin (milk SM), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). By using fluorescent probes 1,6-diphenyl-1,3,5-hexatriene and 6-dodecanoyl-2-dimethylaminonaphthalene, the microenvironments of submicron-sized membranes of exosome and model liposomes were investigated. The membrane fluidity of milk exosome was slightly higher than those of Chol/milk SM/POPC liposomes with a similar content of Chol, suggesting the presence of enriched unsaturated lipids. The most purposeful membrane property was obtained by the liposome composition of Chol/milk SM/POPC = 40/15/45. From the above, it is concluded that Chol is a fundamental component of the milk exosomal membrane to construct the enriched l_o phase, which could increase the membrane rigidity and contribute to the function of exosome.

High-quality milk exosomes as oral drug delivery system

Many drugs must be administered intravenously instead of oral administration due to their poor oral bioavailability. The cost of repeated infusion treatment for 6 weeks every year is as high as tens of billions of dollars worldwide. Exosomes are nano-sized (30-150 nm) extracellular vesicles secreted by mammalian cells due to environmental stimulation or self-activation. Milk contains abundant exosomes originated from multiple cellular sources. It has been proved that milk exosomes (MEs) could survive with the strongly acidic conditions in the stomach and degradative conditions in the gut. Furthermore, they can cross biological barriers to reach targeted tissues. The ability of MEs to cross the gastrointestinal barrier makes them as a promising drug delivery tool for oral delivery. This review is devoted to the purification of MEs, their biocompatibility and immunogenicity, and prospects for their use as natural drug carriers for oral administration.

Extracellular vesicles as the "magic bullet" for fighting threats to humanity

Many researchers worldwide are currently trying to develop targeted molecular therapies such as nucleic acid medicines or antibody-drug conjugates for various diseases. Writing in Extracellular Vesicles and Circulating Nucleic Acids, Kim et al. summarized existing technologies for encapsulating therapeutic molecules into exosomes and introduced some human cell lines which are able to produce safe, effective therapeutic exosomes. Their review article offers the "magic bullet" for fighting threats to humanity such as the current coronavirus pandemic.

New insights into exosome mediated tumor-immune escape: Clinical perspectives and therapeutic strategies

Recent advances in extracellular vesicle biology have uncovered a substantial role in maintaining cell homeostasis in health and disease conditions by mediating intercellular communication, thus catching the scientific community's attention worldwide. Extracellular microvesicles, some called exosomes, functionally transfer biomolecules such as proteins and non-coding RNAs from one cell to another, influencing the local environment's biology. Although numerous advancements have been made in treating cancer patients with immune therapy, controlling the disease remains a challenge in the clinic due to tumor-driven interference with the immune response and inability of immune cells to clear cancer cells from the body. The present review article discusses the recent findings and knowledge gaps related to the role of exosomes derived from tumors and the tumor microenvironment cells in tumor escape from immunosurveillance. Further, we highlight examples where exosomal non-coding RNAs influence immune cells' response within the tumor microenvironment and favor tumor growth and progression. Therefore, exosomes can be used as a therapeutic target for the treatment of human cancers.

Comprehensive Proteomic Analysis Revealed a Large Number of Newly Identified Proteins in the Small Extracellular Vesicles of Milk from Late-Stage Lactating Cows

Bovine milk contains small extracellular vesicles (sEVs) that provide proteins, miRNAs, mRNAs, DNAs, and lipids to target cells and play a role in intracellular communications. Previous studies have characterized proteins in milk sEVs from early- and mid-stage lactation. However, the proteins in milk sEVs from late-stage lactation are mostly unexplored. The aim of this study was to determine the proteomic profile of milk sEVs from late-stage lactating cows. A comprehensive nanoliquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) approach was carried out to reveal the proteins in milk sEVs. Additionally, bioinformatics analysis was carried out to interpret the molecular signatures of newly identified proteins in milk sEVs from three late-stage lactating cows. NanoLC-MS/MS analysis revealed a total of 2225 proteins in milk sEVs from cows. Notably, after comparing these identified proteins with previously deposited datasets of proteins in bovine milk sEVs, 429 proteins were detected as newly identified. Bioinformatic analysis indicated that these newly identified proteins in milk sEVs were engaged in a diverse range of molecular phenomena relevant to mammary gland physiology, milk production, immunity, and immune response. These findings suggest that the newly identified proteins could expand the inventory application of molecular cargos, nutritional status, and immune modulation of sEVs in milk during the late-stage lactation.

Synthesized nanoparticles, biomimetic nanoparticles and extracellular vesicles for treatment of autoimmune disease: Comparison and prospect

An emerging strategy is needed to treat autoimmune diseases, many of which are chronic with no definitive cure. Current treatments only alleviate symptoms and have many side effects affecting patient quality of life. Recently, nanoparticle drug delivery systems, an emerging method in medicine, has been used to target cells or organs, without damaging normal tissue. This approach has led to fewer side effects, along with a strong immunosuppressive capacity. Therefore, a nanotechnology approach may help to improve the treatment of autoimmune diseases. In this review, we separated nanoparticles into three categories: synthesized nanoparticles, biomimetic nanoparticles, and extracellular vesicles. This review firstly compares the typical mechanism of action of these three nanoparticle categories respectively in terms of active targeting, camouflage effect, and similarity to parent cells. Then their immunomodulation properties are discussed. Finally, the challenges faced by all these nanoparticles are described.

Flood Control: How Milk-Derived Extracellular Vesicles Can Help to Improve the Intestinal Barrier Function and Break the Gut-Joint Axis in Rheumatoid Arthritis

Many studies provided compelling evidence that extracellular vesicles (EVs) are involved in the regulation of the immune response, acting as both enhancers and dampeners of the immune system, depending on the source and type of vesicle. Research, including ours, has shown anti-inflammatory effects of milk-derived EVs, using human breast milk as well as bovine colostrum and store-bought pasteurized cow milk, in in vitro systems as well as therapeutically in animal models. Although it is not completely elucidated which proteins and miRNAs within the milk-derived EVs contribute to these immunosuppressive capacities, one proposed mechanism of action of the EVs is via the modulation of the crosstalk between the (intestinal) microbiome and their host health. There is increasing awareness that the gut plays an important role in many inflammatory diseases. Enhanced intestinal leakiness, dysbiosis of the gut microbiome, and bowel inflammation are not only associated with intestinal diseases like colitis and Crohn's disease, but also characteristic for systemic inflammatory diseases such as lupus, multiple sclerosis, and rheumatoid arthritis (RA). Strategies to target the gut, and especially its microbiome, are under investigation and hold a promise as a therapeutic intervention for these diseases. The use of milk-derived EVs, either as stand-alone drug or as a drug carrier, is often suggested in recent years. Several research groups have studied the tolerance and safety of using milk-derived EVs in animal models. Due to its composition, milk-derived EVs are highly biocompatible and have limited immunogenicity even cross species. Furthermore, it has been demonstrated that milk-derived EVs, when taken up in the gastro-intestinal tract, stay intact after absorption, indicating excellent stability. These characteristics make milk-derived EVs very suitable as drug carriers, but also by themselves, these EVs already have a substantial immunoregulatory function, and even without loading, these vesicles can act as therapeutics. In this review, we will address the immunomodulating capacity of milk-derived EVs and discuss their potential as therapy for RA patients.

Review criteria

The search terms "extracellular vesicles", "exosomes", "microvesicles", "rheumatoid arthritis", "gut-joint axis", "milk", and "experimental arthritis" were used. English-language full text papers (published between 1980 and 2021) were identified from PubMed and Google Scholar databases. The reference list for each paper was further searched to identify additional relevant articles.

Ruminant Milk-Derived Extracellular Vesicles: A Nutritional and Therapeutic Opportunity?

Milk has been shown to contain a specific fraction of extracellular particles that are reported to resist digestion and are purposefully packaged with lipids, proteins, and nucleic acids to exert specific biological effects. These findings suggest that these particles may have a role in the quality of infant nutrition, particularly in the early phase of life when many of the foundations of an infant's potential for health and overall wellness are established. However, much of the current research focuses on human or cow milk only, and there is a knowledge gap in how milk from other species, which may be more commonly consumed in different regions, could also have these reported biological effects. Our review provides a summary of the studies into the extracellular particle fraction of milk from a wider range of ruminants and pseudo-ruminants, focusing on how this fraction is isolated and characterised, the stability and uptake of the fraction, and the reported biological effects of these fractions in a range of model systems. As the individual composition of milk from different species is known to differ, we propose that the extracellular particle fraction of milk from non-traditional and minority species may also have important and distinct biological properties that warrant further study.

Preserving extracellular vesicles for biomedical applications: consideration of storage stability before and after isolation

Extracellular vesicles (EVs) are nanovesicles released by various cell types. EVs are known for cell-to-cell communications and have potent biological activities. Despite great progress in recent years for studies exploring the potentials of EVs for early disease detection, therapeutic application and drug delivery, determination of the favorable storage conditions of EVs has been challenging. The understanding of the impact of storage conditions on EVs before and after isolation is still limited. Storage may change the size, number, contents, functions, and behaviors of EVs. Here, we summarized current studies about the stability of EVs in different conditions, focusing on temperatures, durations, and freezing and thawing cycles. -80 °C seems to remain the most favorable condition for storage of biofluids and isolated EVs, while isolated EVs may be stored at 4 °C shortly. Lyophilization is promising for storage of EV products. Challenges remain in the understanding of storage-mediated change in EVs and in the development of advanced preservation techniques of EVs.

Extracellular vesicles as a next-generation drug delivery platform

Extracellular-vesicle-based cell-to-cell communication is conserved across all kingdoms of life. There is compelling evidence that extracellular vesicles are involved in major (patho)physiological processes, including cellular homoeostasis, infection propagation, cancer development and cardiovascular diseases. Various studies suggest that extracellular vesicles have several advantages over conventional synthetic carriers, opening new frontiers for modern drug delivery. Despite extensive research, clinical translation of extracellular-vesicle-based therapies remains challenging. Here, we discuss the uniqueness of extracellular vesicles along with critical design and development steps required to utilize their full potential as drug carriers, including loading methods, in-depth characterization and large-scale manufacturing. We compare the prospects of extracellular vesicles with those of the well established liposomes and provide guidelines to direct the process of developing vesicle-based drug delivery systems.

Biological Properties of Milk-Derived Extracellular Vesicles and Their Physiological Functions in Infant

Extracellular vesicles (EVs) are released by all cells under pathological and physiological conditions. EVs harbor various biomolecules, including protein, lipid, non-coding RNA, messenger RNA, and DNA. In 2007, mRNA and microRNA (miRNA) carried by EVs were found to have regulatory functions in recipient cells. The biological function of EVs has since then increasingly drawn interest. Breast milk, as the most important nutritional source for infants, contains EVs in large quantities. An increasing number of studies have provided the basis for the hypothesis associated with information transmission between mothers and infants via breast milk-derived EVs. Most studies on milk-derived EVs currently focus on miRNAs. Milk-derived EVs contain diverse miRNAs, which remain stable both in vivo and in vitro; as such, they can be absorbed across different species. Further studies have confirmed that miRNAs derived from milk-derived EVs can resist the acidic environment and enzymatic hydrolysis of the digestive tract; moreover, they can be absorbed by intestinal cells in infants to perform physiological functions. miRNAs derived from milk EVs have been reported in the maturation of immune cells, regulation of immune response, formation of neuronal synapses, and development of metabolic diseases such as obesity and diabetes. This article reviews current status and advances in milk-derived EVs, including their history, biogenesis, molecular contents, and biological functions. The effects of milk-derived EVs on growth and development in both infants and adults were emphasized. Finally, the potential application and future challenges of milk-derived EVs were discussed, providing comprehensive understanding and new insight into milk-derived EVs.

Oral administration of bovine milk-derived extracellular vesicles induces senescence in the primary tumor but accelerates cancer metastasis

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors.

Milk exosomes with enhanced mucus penetrability for oral delivery of siRNA

Bovine milk-derived exosomes have recently emerged as a promising nano-vehicle for the encapsulation and delivery of macromolecular biotherapeutics. Here we engineer high purity bovine milk exosomes (mExo) with modular surface tunability for oral delivery of small interfering RNA (siRNA). We utilize a low-cost enrichment method combining casein chelation with differential ultracentrifugation followed by size exclusion chromatography, yielding mExo of high concentration and purity. Using in vitro models, we demonstrate that negatively charged hydrophobic mExos can penetrate multiple biological barriers to oral drug delivery. A hydrophilic polyethylene glycol (PEG) coating was introduced on the mExo surface via passive, stable hydrophobic insertion of a conjugated lipid tail, which significantly reduced mExo degradation in acidic gastric environment and enhanced their permeability through mucin by over 3× compared to unmodified mExo. Both mExo and PEG-mExo exhibited high uptake by intestinal epithelial cells and mediated functional intracellular delivery of siRNA, thereby suppressing the expression of the target green fluorescence protein (GFP) gene by up to 70%. We also show that cationic chemical transfection is significantly more efficient in loading siRNA into mExo than electroporation. The simplicity of isolating high purity mExo in high concentrations and equipping them with tunable surface properties, demonstrated here, paves way for the development of mExo as an effective, scalable platform technology for oral drug delivery of siRNA.

Regular Industrial Processing of Bovine Milk Impacts the Integrity and Molecular Composition of Extracellular Vesicles

BACKGROUND

Bovine milk contains extracellular vesicles (EVs), which act as mediators of intercellular communication by regulating the recipients' cellular processes via their selectively incorporated bioactive molecules. Because some of these EV components are evolutionarily conserved, EVs present in commercial milk might have the potential to regulate cellular processes in human consumers.

OBJECTIVES

Because commercial milk is subjected to industrial processing, we investigated its effect on the number and integrity of isolated milk EVs and their bioactive components. For this, we compared EVs isolated from raw bovine milk with EVs isolated from different types of commercial milk, including pasteurized milk, either homogenized or not, and ultra heat treated (UHT) milk.

METHODS

EVs were separated from other milk components by differential centrifugation, followed by density gradient ultracentrifugation. EVs from different milk types were compared by single-particle high-resolution fluorescence-based flow cytometry to determine EV numbers, Cryo-electron microscopy to visualize EV integrity and morphology, western blot analysis to investigate EV-associated protein cargo, and RNA analysis to assess total small RNA concentration and milk-EV-specific microRNA expression.

RESULTS

In UHT milk, we could not detect intact EVs. Interestingly, although pasteurization (irrespective of homogenization) did not affect mean ± SD EV numbers (3.4 × 108 ± 1.2 × 108-2.8 × 108 ± 0.3 × 107 compared with 3.1 × 108 ± 1.2 × 108 in raw milk), it affected EV integrity and appearance, altered their protein signature, and resulted in a loss of milk-EV-associated RNAs (from 40.2 ± 3.4 ng/μL in raw milk to 17.7 ± 5.4-23.3 ± 10.0 mg/μL in processed milk, P < 0.05).

CONCLUSIONS

Commercial milk, that has been heated by either pasteurization or UHT, contains fewer or no intact EVs, respectively. Although most EVs seemed resistant to pasteurization based on particle numbers, their integrity was affected and their molecular composition was altered. Thus, the possible transfer of bioactive components via bovine milk EVs to human consumers is likely diminished or altered in heat-treated commercial milk.

A focus on critical aspects of uptake and transport of milk-derived extracellular vesicles across the Caco-2 intestinal barrier model

Bovine milk-derived extracellular vesicles (EVs) hold promises as oral drug delivery systems. Since EV bioavailability studies are difficult to compare, key factors regarding EV uptake and intestinal permeability remain little understood. This work aims to critically study uptake and transport properties of milk-derived EVs across the intestinal barrier in vitro by standardization approaches. Therefore, uptake properties were directly compared to liposomes in intestinal Caco-2 cells. Reliable staining results were obtained by the choice of three distinct EV labeling sites, while non-specific dye transfer and excess dye removal were carefully controlled. A novel fluorescence correction factor was implemented to account for different labeling efficiencies. Both EV and liposome uptake occurred mainly energy dependent with the neonatal Fc receptor (FcRn) providing an exclusive active pathway for EVs. Confocal microscopy revealed higher internalization of EVs whereas liposomes rather remained attached to the cell surface. Internalization could be improved when changing the liposomal formulation to resemble the EV lipid composition. In a Caco-2/HT29-MTX co-culture liposomes and EVs showed partial mucus penetration. For transport studies across Caco-2 monolayers we further established a standardized protocol considering the distinct requirements for EVs. Especially insert pore sizes were systematically compared with 3 µm inserts found obligatory. Obtained apparent permeability coefficients (P_app) reflecting the transport rate will allow for better comparison of future bioavailability testing.

Engineering Extracellular Vesicles to Target Pancreatic Tissue In Vivo

Extracellular vesicles (EVs) are naturally released, cell-derived vesicles that mediate intracellular communication, in part, by transferring genetic information and, thus, have the potential to be modified for use as a therapeutic gene or drug delivery vehicle. Advances in EV engineering suggest that directed delivery can be accomplished via surface alterations. Here we assess enriched delivery of engineered EVs displaying an organ targeting peptide specific to the pancreas. We first characterized the size, morphology, and surface markers of engineered EVs that were decorated with a recombinant protein specific to pancreatic β-cells. This β-cell-specific recombinant protein consists of the peptide p88 fused to the EV-binding domain of lactadherin (C1C2). These engineered EVs, p88-EVs, specifically bound to pancreatic β-cells in culture and transferred encapsulated plasmid DNA (pDNA) as early as in 10 min suggesting that the internalization of peptide-bearing EVs is a rapid process. Biodistribution of p88-EVs administrated intravenously into mice showed an altered pattern of EV localization and improved DNA delivery to the pancreas relative to control EVs, as well as an accumulation of targeting EVs to the pancreas using luciferase activity as a readout. These findings demonstrate that systemic administration of engineered EVs can efficiently deliver their cargo as gene carriers to targeted organs in live animals.

Eating microRNAs: pharmacological opportunities for cross-kingdom regulation and implications in host gene and gut microbiota modulation

Cross-kingdom communication via non-coding RNAs is a recent discovery. Exogenous microRNAs (exog-miRNAs) mainly enter the host via the diet. Generally considered unstable in the gastrointestinal tract, some exogenous RNAs may resist these conditions, especially if transported in extracellular vesicles. They could then reach the intestines and more probably exert a regulatory effect. We give an overview of recent discoveries concerning dietary miRNAs, possible ways of enhancing their resistance to food processing and gut conditions, their transport in extracellular vesicles (animal- and plant-origin) and possible biological effects on recipient cells after ingestion. We critically focus on what we believe are the most relevant data for future pharmacological development of dietary miRNAs as therapeutic agents. Finally, we discuss the miRNA-mediated cross-kingdom regulation between diet, host and the gut microbiota. We conclude that, despite many obstacles and challenges, extracellular miRNAs are serious candidates to be targeted pharmacologically for development of new therapeutic agents.

Temporal Quantitative Proteomics Analysis of Neuroblastoma Cells Treated with Bovine Milk-Derived Extracellular Vesicles Highlights the Anti-Proliferative Properties of Milk-Derived Extracellular Vesicles

Neuroblastoma (NBL) is a pediatric cancer that accounts for 15% of childhood cancer mortality. Amplification of the oncogene N-Myc occurs in 20% of NBL patients and is considered high risk as it correlates with aggressiveness, treatment resistance and poor prognosis. Even though the treatment strategies have improved in the recent years, the survival rate of high-risk NBL patients remain poor. Hence, it is crucial to explore new therapeutic avenues to sensitise NBL. Recently, bovine milk-derived extracellular vesicles (MEVs) have been proposed to contain anti-cancer properties. However, the impact of MEVs on NBL cells is not understood. In this study, we characterised MEVs using Western blotting, NTA and TEM. Importantly, treatment of NBL cells with MEVs decreased the proliferation and increased the sensitivity of NBL cells to doxorubicin. Temporal label-free quantitative proteomics of NBL cells highlighted the depletion of proteins involved in cell metabolism, cell growth and Wnt signalling upon treatment with MEVs. Furthermore, proteins implicated in cellular senescence and apoptosis were enriched in NBL cells treated with MEVs. For the first time, this study highlights the temporal proteomic profile that occurs in cancer cells upon MEVs treatment.

Milk-Derived Extracellular Vesicles Suppress Inflammatory Cytokine Expression and Nuclear Factor-κB Activation in Lipopolysaccharide-Stimulated Macrophages

In milk and milk products, small membrane-enclosed vesicles can be found, commonly termed extracellular vesicles (EVs). Milk-derived EVs have previously been suggested to have immunoregulatory properties, especially important for infants without a fully functioning immune system. In the present study, EV fractions were isolated from human milk, mature and colostrum bovine milk, and two dairy fractions, and successively surveyed for their immunomodulating effects on lipopolysaccharide (LPS)-stimulated macrophages (RAW264.7). RAW264.7 cell material and supernatant were evaluated by monitoring degradation of IκBα in the NF-κB pathway, and IL-6 and IL-1β cytokine production, using Western blotting and enzyme-linked immunosorbent assaying, respectively. The results revealed that preincubation with EVs derived from raw human and bovine milk lowered the LPS-activated response of the NF-κB pathway. Additionally, it was found that preincubation with EVs, from human and bovine milk as well as dairy whey or skim milk-derived fractions, decreased secretion of proinflammatory cytokines from LPS-activated RAW264.7 cells. The findings that milk-derived EVs can change the inflammatory response in macrophages support the notion that milk EVs have an important role in mother-to-infant communication and protection of a newborn.

Comparison of isolation methods using commercially available kits for obtaining extracellular vesicles from cow milk

Extracellular vesicles (EV) are important for delivering biologically active substances to facilitate cell-to-cell communication. Milk-derived EV are widely known because of their potential for immune enhancement. However, procedures for isolating milk-derived EV have not been fully established. To obtain pure milk-derived EV and accurately reveal their function, such procedures must be established. The aim of the present study was to compare methods using commercially available kits for isolating milk-derived EV. Initially, we investigated procedures to remove casein, which is the major obstacle in determining milk-derived EV purity. We separated whey using centrifugation only, acetic acid precipitation, and EDTA precipitation. Then, we isolated milk-derived EV by ultracentrifugation, membrane affinity column, size exclusion chromatography (SEC), polymer-based isolation, or phosphatidylserine-affinity isolation. Using EV count per milligram of protein, which is a good indicator of purity, we determined that acetic acid precipitation was the best method for removing casein. Using nanoparticle tracking analysis, protein quantity analysis, and RNA quantity analysis, we comprehensively compared each isolation method for its purity and yield. We found that SEC-based qEV column (Izon Science) could collect purer milk-derived EV at higher quantities. Thus, a combination of acetic acid precipitation and qEV can effectively isolate high amounts of pure extracellular vesicles from bovine milk.

Extracellular vesicles from recombinant cell factories improve the activity and efficacy of enzymes defective in lysosomal storage disorders

In the present study the use of extracellular vesicles (EVs) as vehicles for therapeutic enzymes in lysosomal storage disorders was explored. EVs were isolated from mammalian cells overexpressing alpha-galactosidase A (GLA) or N-sulfoglucosamine sulfohydrolase (SGSH) enzymes, defective in Fabry and Sanfilippo A diseases, respectively. Direct purification of EVs from cell supernatants was found to be a simple and efficient method to obtain highly active GLA and SGSH proteins, even after EV lyophilization. Likewise, EVs carrying GLA (EV-GLA) were rapidly uptaken and reached the lysosomes in cellular models of Fabry disease, restoring lysosomal functionality much more efficiently than the recombinant enzyme in clinical use. In vivo, EVs were well tolerated and distributed among all main organs, including the brain. DiR-labelled EVs were localized in brain parenchyma 1 h after intra-arterial (internal carotid artery) or intravenous (tail vein) administrations. Moreover, a single intravenous administration of EV-GLA was able to reduce globotriaosylceramide (Gb3) substrate levels in clinically relevant tissues, such kidneys and brain. Overall, our results demonstrate that EVs from cells overexpressing lysosomal enzymes act as natural protein delivery systems, improving the activity and the efficacy of the recombinant proteins and facilitating their access to organs neglected by conventional enzyme replacement therapies.

Optimisation and comparison of orthogonal methods for separation and characterisation of extracellular vesicles to investigate how representative infant milk formula is of milk

Many infants are fed infant milk formula (IMF). However, IMF production from skim milk (SM) involves harsh treatment. So, we hypothesised that the quantity and/or quality of extracellular vesicles (EVs) in IMF may be reduced. Thus, firstly, we aimed to optimise separation of EVs from IMF and SM and, secondly, we aimed to compare the EV isolates from these two sources. Prior to EV isolation, abundant casein micelles of similar sizes to EVs were removed by treating milk samples with either acetic acid or hydrochloric acid. Samples progressed to differential ultracentrifugation (DUC) or gradient ultracentrifugation (GUC). EV characterisation included BCA, SDS-PAGE, nanoparticle tracking (NTA), electron microscopy (TEM), immunoblotting, and imaging flow cytometry (IFCM). Reduced EV concentrations were found in IMF. SM-derived EVs were intact, while IMF contained disrupted EV-like structures. EV biomarkers were more abundant with isolates from SM, indicating EV proteins in IMF are compromised. Altogether, a suitable method combining acid pre-treatment with GUC for EV separation from milk products was developed. EVs appear to be substantially compromised in IMF compared to SM.

General and mild modification of food-derived extracellular vesicles for enhanced cell targeting

Food-derived extracellular vesicles (FDEVs) have attracted increasing attention as potential delivery vehicles for therapeutic agents due to their desirable features such as excellent biocompatibility, easy accessibility and cost effectiveness. However, the intrinsic targeting capability of FDEVs is unsatisfactory compared to artificial nanoparticles or other source-derived EVs, which calls for efficient surface engineering strategies to equip them with specific ligands. Here we report a general and mild modification method via reduction of disulfide groups to maleimide reactive thiols. Taking milk-derived EVs (mEVs) as a model system, we demonstrated the feasibility for tethering various ligands on the surface without compromising the vesicular structures. Building an ultra-sensitive nano-flow cytometer (nFCM), the heterogeneous nature of the functionalized samples was revealed, and a magnetic separation approach was proposed accordingly to remove the as-observed non-EV particles. The cellular uptake and cytotoxicity experiments provided direct evidence showing an enhanced cell targeting and cargo delivery capability of the ligand conjugated mEVs. In addition, the in vivo imaging further proved the applicability of transferrin conjugation for increased tumor enrichment of mEVs. Collectively, this general and mild ligand conjugation method enables an efficient surface functionalization of FDEVs, which is of vital importance for enhanced targeting delivery.

Proteomic profiling of milk small extracellular vesicles from bovine leukemia virus-infected cattle

Milk small extracellular vesicles (sEV) contain proteins that provide potential information of host physiology and immunology. Bovine leukemia virus (BLV) is an oncogenic virus that causes progressive B-cell lymphosarcoma in cattle. In this study, we aimed to explore the proteomic profile of milk sEV from BLV-infected cattle compared with those from uninfected cattle. Milk sEV were isolated from three BLV-infected and three uninfected cattle. Proteomic analysis was performed by using a comprehensive nanoLC-MS/MS method. Furthermore, gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were used to evaluate the candidates for uniquely or differentially expressed proteins in milk sEV from BLV-infected cattle. Proteomic analysis revealed a total of 1330 common proteins in milk sEV among BLV-infected cattle, whereas 118 proteins were uniquely expressed compared with those from uninfected cattle. Twenty-six proteins in milk sEV were differentially expressed proteins more than two-fold significant difference (p < 0.05) in BLV-infected cattle. GO and KEGG analyses indicated that the candidates for uniquely or differentially expressed proteins in milk sEV had been involved in diverse biological activities including metabolic processes, cellular processes, respond to stimulus, binding, catalytic activities, cancer pathways, focal adhesion, and so on. Taken together, the present findings provided a novel insight into the proteomes of milk sEV from BLV-infected cattle.

Milk exosomes: A biogenic nanocarrier for small molecules and macromolecules to combat cancer

Exosomes are unique biogenic nanocarriers of endocytic origin that are generated from most of the cells and found in biofluids like milk, plasma, saliva, and urine. Bovine milk represents the largest and an economic source for the production of exosomes. In recent past, the utility of the milk exosomes as drug carriers is intensified. Exosomes are emerging for delivery of both small and large therapeutics due to their biocompatibility. In this article, we highlighted the various exosomal isolation techniques, physicochemical properties, their biodistribution, and utility of milk exosomes in delivering the small drug molecules and siRNA to combat cancer.