Review: Milk Small Extracellular Vesicles for Use in the Delivery of Therapeutics

Microscopic messengers: Extracellular vesicles shaping gastrointestinal health and disease

The field of extracellular vesicles (EVs) is advancing rapidly, and this review aims to synthesize the latest research connected to EVs and the gastrointestinal tract. We will address new and emerging roles for EVs derived from internal sources such as the pancreas and immune system and how these miniature messengers alter organismal health or the inflammatory response within the GI tract. We will examine what is known about external EVs from dietary and bacterial sources and the immense anti-inflammatory, immune-modulatory, and proliferative potential within these nano-sized information carriers. EV interactions with the intestinal and colonic epithelium and associated immune cells at homeostatic and disease states, such as necrotizing enterocolitis (NEC) and inflammatory bowel disease (IBD) will also be covered. We will discuss how EVs are being leveraged as therapeutics or for drug delivery and conclude with a series of unanswered questions in the field.

Orally Delivered Milk-Derived Nanovesicles Loaded with Connexin 43 Peptides for Targeted Cardiac Ischemia-Reperfusion Therapy

Extracellular vesicles have emerged as promising nanocarriers for targeted drug delivery, but their therapeutic potential is limited by challenges related to administration route, loading, targeted delivery and production at scale. Here, we report an innovative approach for targeted delivery of therapeutic peptides to injured tissues using milk-derived small extracellular vesicles (mEVs) as an abundant, safe, orally administrable nanoplatform. We demonstrate that a sub-population of mEVs naturally contain Connexin 43 (Cx43) and its Carboxyl-Terminal (CT) polypeptides, which have been shown to play crucial roles in wound healing and tissue repair. Leveraging this intrinsic property, we developed an esterification method to efficiently and uniformly load mEVs with enhanced levels of an exogenous Cx43 CT peptide (αCT11 - RPRPDDLEI), as assessed by flow cytometry-based vesicle quantification and mass spectrometry. These engineered mEVs exhibited remarkable injury targeting capabilities, with > 30-fold increases in uptake by injured cells compared to non-wounded cells in vitro and preferential accumulation in wounded tissues in vivo. Notably, αCT11-loaded mEVs orally administered after myocardial infarction reduced infarct size by >60% and preserved heart function in a mouse model of ischemia-reperfusion injury. This study represents a significant advance in nanomedicine, demonstrating the utilization of naturally occurring milk-derived extracellular vesicles as an oral delivery system for therapeutic peptides, achieving unprecedented targeting efficiency and efficacy in the treatment of myocardial ischemia-reperfusion injury.

Toward the nanoscale chemical and physical probing of milk-derived extracellular vesicles using Raman and tip-enhanced Raman spectroscopy

Tip-enhanced Raman spectroscopy (TERS) is an advanced technique to perform local chemical analysis of the surface of a sample through the improvement of the sensitivity and the spatial resolution of Raman spectroscopy by plasmonic enhancement of the electromagnetic signal in correspondence with the nanometer-sized tip of an atomic force microscope (AFM). In this work, TERS is demonstrated to represent an innovative and powerful approach for studying extracellular vesicles, in particular bovine milk-derived extracellular vesicles (mEVs), which are nanostructures with considerable potential in drug delivery and therapeutic applications. Raman spectroscopy has been used to analyze mEVs at the micrometric and sub-micrometric scales to obtain a detailed Raman spectrum in order to identify the 'signature' of mEVs in terms of their characteristic molecular vibrations and, therefore, their chemical compositions. With the ability to improve lateral resolution, TERS has been used to study individual mEVs, demonstrating the possibility of investigating a single mEV selected on the surface of the sample and, moreover, analyzing specific locations on the selected mEV with nanometer lateral resolution. TERS potentially allows one to reveal local differences in the composition of mEVs providing new insights into their structure. Also, thanks to the intrinsic properties of TERS to acquire the signal from only the first few nanometers of the surface, chemical investigation of the lipid membrane in correspondence with the various locations of the selected mEV could be performed by analyzing the peaks of the Raman shift in the relevant range of the spectrum (2800-3000 cm-1). Despite being limited to mEVs, this work demonstrates the potential of TERS in the analysis of extracellular vesicles.

Neonatal enteroids absorb extracellular vesicles from human milk-fed infant digestive fluid

Human milk contains extracellular vesicles (HMEVs). Pre-clinical models suggest that HMEVs may enhance intestinal function and limit inflammation; however, it is unknown if HMEVs or their cargo survive neonatal human digestion. This limits the ability to leverage HMEV cargo as additives to infant nutrition or as therapeutics. This study aimed to develop an EV isolation pipeline from small volumes of human milk and neonatal intestinal contents after milk feeding (digesta) to address the hypothesis that HMEVs survive in vivo neonatal digestion to be taken up intestinal epithelial cells (IECs). Digesta was collected from nasoduodenal sampling tubes or ostomies. EVs were isolated from raw and pasteurized human milk and digesta by density-gradient ultracentrifugation following two-step skimming, acid precipitation of caseins, and multi-step filtration. EVs were validated by electron microscopy, western blotting, nanoparticle tracking analysis, resistive pulse sensing, and super-resolution microscopy. EV uptake was tested in human neonatal enteroids. HMEVs and digesta EVs (dEVs) show typical EV morphology and are enriched in CD81 and CD9, but depleted of β-casein and lactalbumin. HMEV and some dEV fractions contain mammary gland-derived protein BTN1A1. Neonatal human enteroids rapidly take up dEVs in part via clathrin-mediated endocytosis. Our data suggest that EVs can be isolated from digestive fluid and that these dEVs can be absorbed by IECs.

Advances in separation and identification of biologically important milk proteins and peptides

Milk is a rich source of biologically important proteins and peptides. In addition, milk contains a variety of extracellular vesicles (EVs), including exosomes, that carry their own proteome cargo. EVs are essential for cell-cell communication and modulation of biological processes. They act as nature carriers of bioactive proteins/peptides in targeted delivery during various physiological and pathological conditions. Identification of the proteins and protein-derived peptides in milk and EVs and recognition of their biological activities and functions had a tremendous impact on food industry, medicine research, and clinical applications. Advanced separation methods, mass spectrometry (MS)-based proteomic approaches and innovative biostatistical procedures allowed for characterization of milk protein isoforms, genetic/splice variants, posttranslational modifications and their key roles, and contributed to novel discoveries. This review article discusses recently published developments in separation and identification of bioactive proteins/peptides from milk and milk EVs, including MS-based proteomic approaches.

Milk-derived small extracellular vesicles: a new perspective on dairy nutrition

Milk contains bioactive compounds that have multiple essential benefits. Milk-derived small extracellular vesicles (M-sEVs) have emerged as novel bioactive milk components with various beneficial biological functions and broad applications. The M-sEVs from different mammalian sources have similar composition and bioactive functions. The digestive stability and biocompatibility of the M-sEVs provide a good foundation for their physiological functions. Evidence suggests that M-sEVs promote intestinal, immune, bone, neural, liver, and heart health and show therapeutic effects against cancer, indicating their potential for use in functional foods. In addition, M-sEVs can be developed as natural delivery carriers owing to their superior structural characteristics. Further studies are needed to elucidate the relationship between the specific components and functions of M-sEVs, standardize their extraction processes, and refine relevant clinical trials to advance the future applications of M-sEVs. This review summarizes the structure and composition of M-sEVs isolated from different milk sources and discusses several common extraction methods. Since the introduction of M-sEVs for digestion and absorption, studies have been conducted on their biological functions. Furthermore, we outline the theoretical industrial production route, potential application scenarios of M-sEVs, and the future perspectives of M-sEV research.

Living Cells and Cell-Derived Vesicles: A Trojan Horse Technique for Brain Delivery

Brain diseases remain a significant global healthcare burden. Conventional pharmacological therapy for brain diseases encounters huge challenges because of the blood-brain barrier (BBB) limiting the delivery of therapeutics into the brain parenchyma. To address this issue, researchers have explored various types of drug delivery systems. Cells and cell derivatives have attracted increasing interest as "Trojan horse" delivery systems for brain diseases, owing to their superior biocompatibility, low immunogenicity, and BBB penetration properties. This review provided an overview of recent advancements in cell- and cell-derivative-based delivery systems for the diagnosis and treatment of brain diseases. Additionally, it discussed the challenges and potential solutions for clinical translation.

The RNA cargo in small extracellular vesicles from chicken eggs is bioactive in C57BL/6 J mice and human peripheral blood mononuclear cells ex vivo

Small extracellular vesicles (sEVs) and their RNA cargo in milk are bioavailable in humans, pigs, and mice, and their dietary depletion and supplementation elicits phenotypes. Little is known about the content and biological activity of sEVs in foods of animal origin other than milk. Here we tested the hypothesis that sEVs in chicken eggs (Gallus gallus) facilitate the transfer of RNA cargo from an avian species to humans and mice, and their dietary depletion elicits phenotypes. sEVs were purified from raw egg yolk by ultracentrifugation and authenticated by transmission electron microscopy, nano-tracking device, and immunoblots. The miRNA profile was assessed by RNA-sequencing. Bioavailability of these miRNAs in humans was assessed by egg feeding study in adults, and by culturing human peripheral blood mononuclear cells (PBMCs) with fluorophore-labeled egg sEVs ex vivo. To further assess bioavailability, fluorophore-labeled miRNAs, encapsulated in egg sEVs, were administered to C57BL/6 J mice by oral gavage. Phenotypes of sEV RNA cargo depletion were assessed by feeding egg sEV and RNA-defined diets to mice and using spatial learning and memory in the Barnes and water mazes as experimental readouts. Egg yolk contained 6.30 × 10¹⁰ ± 6.06 × 10⁹ sEVs/mL, which harbored eighty-three distinct miRNAs. Human PBMCs internalized sEVs and their RNA cargo. Egg sEVs, loaded with fluorophore-labeled RNA and administered orally to mice, accumulated primarily in brain, intestine and lungs. Spatial learning and memory (SLM) was compromised in mice fed on egg sEV- and RNA-depleted diet compared to controls. Egg consumption elicited an increase of miRNAs in human plasma. We conclude that egg sEVs and their RNA cargo probably are bioavailable. The human study is registered as a clinical trial and accessible at https://www.isrctn.com/ISRCTN77867213.

Milk Exosomal miR-27b Worsen Endoplasmic Reticulum Stress Mediated Colorectal Cancer Cell Death

The relationship between dietary constituents and the onset and prevention of colorectal cancer (CRC) is constantly growing. Recently, the antineoplastic profiles of milk and whey from Mediterranean buffalo (Bubalus bubalis) have been brought to attention. However, to date, compared to cow milk, the potential health benefits of buffalo milk exosome-miRNA are still little explored. In the present study, we profiled the exosomal miRNA from buffalo milk and investigated the possible anticancer effects in CRC cells, HCT116, and HT-29. Results indicated that buffalo milk exosomes contained higher levels of miR-27b, miR-15b, and miR-148a compared to cow milk. Mimic miR-27b transfection in CRC cells induced higher cytotoxic effects (p < 0.01) compared to miR-15b and miR-148a. Moreover, miR-27b overexpression in HCT116 and HT-29 cells (miR-27b+) induced apoptosis, mitochondrial reactive oxygen species (ROS), and lysosome accumulation. Exposure of miR-27b+ cells to the bioactive 3kDa milk extract aggravated the apoptosis rate (p < 0.01), mitochondrial stress (p < 0.01), and advanced endoplasmic reticulum (ER) stress (p < 0.01), via PERK/IRE1/XBP1 and CHOP protein modulation (p < 0.01). Moreover, GSK2606414, the ER-inhibitor (ER-i), decreased the apoptosis phenomenon and XBP1 and CHOP modulation in miR-27b+ cells treated with milk (p < 0.01 vs. miR-27b++Milk), suggesting the ER stress as a cell-death-aggravating mechanism. These results support the in vitro anticancer activity of 3kDa milk extract and unveil the contribution of miR-27b in the promising beneficial effect of buffalo milk in CRC prevention.

Extracellular Vesicles from Animal Milk: Great Potentialities and Critical Issues

Other than representing the main source of nutrition for newborn mammals, milk delivers a sophisticated signaling system from mother to child that promotes postnatal health. The bioactive components transferred through the milk intake are important for the development of the newborn immune system and include oligosaccharides, lactoferrin, lysozyme, α-La, and immunoglobulins. In the last 15 years, a pivotal role in this mother-to-child exchange has been attributed to extracellular vesicles (EVs). EVs are micro- and nanosized structures enclosed in a phospholipidic double-layer membrane that are produced by all cell types and released in the extracellular environment, reaching both close and distant cells. EVs mediate the intercellular cross-talk from the producing to the receiving cell through the transfer of molecules contained within them such as proteins, antigens, lipids, metabolites, RNAs, and DNA fragments. The complex cargo can induce a wide range of functional modulations in the recipient cell (i.e., anti-inflammatory, immunomodulating, angiogenetic, and pro-regenerative modulations) depending on the type of producing cells and the stimuli that these cells receive. EVs can be recovered from every biological fluid, including blood, urine, bronchoalveolar lavage fluid, saliva, bile, and milk, which is one of the most promising scalable vesicle sources. This review aimed to present the state-of-the-art of animal-milk-derived EV (mEV) studies due to the exponential growth of this field. A focus on the beneficial potentialities for human health and the issues of studying vesicles from milk, particularly for the analytical methodologies applied, is reported.