Ultrasonication of Milk Decreases the Content of Exosomes and MicroRNAs in an Exosome-Defined Rodent Diet

Milk-Derived Extracellular Vesicles: Biomedical Applications, Current Challenges, and Future Perspectives

Extracellular vesicles (EVs) are nano to-micrometer-sized sacs that are released by almost all animal and plant cells and act as intercellular communicators by transferring their cargos between the source and target cells. As a safe and scalable alternative to conditioned medium-derived EVs, milk-derived EVs (miEVs) have recently gained a great deal of popularity. Numerous studies have shown that miEVs have intrinsic therapeutic actions that can treat diseases and enhance human health. Additionally, they can be used as natural drug carriers and novel classes of biomarkers. However, due to the complexity of the milk, the successful translation of miEVs from benchtop to bedside still faces several unfilled gaps, especially a lack of standardized protocols for the isolation of high-purity miEVs. In this work, by comprehensively reviewing the bovine miEVs studies, we provide an overview of current knowledge and research on miEVs while highlighting their challenges and enormous promise as a novel class of theranostics. It is hoped that this study will pave the way for clinical applications of miEVs by addressing their challenges and opportunities.

Milk-derived exosome nanovesicles: recent progress and daunting hurdles

Raw milk is the foundation of quality and safety in the dairy industry, and improving milk source management is the fundamental guarantee. Milk-derived exosomes (MDEs) are nanoscale information transfer molecules secreted by mammary cells with unique content and high stability, which can be used not only as potential markers to analyze key traits of lactation, reproduction, nutrition and health of animals, but also help farm managers to take timely interventions to improve animal welfare, milk quality, and functional traits. Our review first outlines the latest advances in MDEs isolation and purification, compositional analysis and characterization tools. We then provide a comprehensive summary of recent applications of MDEs liquid biopsy in breed selection, disease prevention and control, and feeding management. Finally, we evaluate the impact of processing on the stability of MDEs to offer guidance for dairy production and storage. The limitations and challenges in the development and use of MDEs markers are also discussed. As a noninvasive marker with high sensitivity and specificity, the MDEs-mediated assay technology is expected to be a powerful tool for measuring cow health and raw milk quality, enabling dynamic and precise regulation of dairy cows and full traceability of raw milk.

From understanding to action: Exploring molecular connections of Down syndrome to Alzheimer's disease for targeted therapeutic approach

Down syndrome (DS) is caused by a third copy of chromosome 21. Alzheimer's disease (AD) is a neurodegenerative condition characterized by the deposition of amyloid-beta (Aβ) plaques and neurofibrillary tangles in the brain. Both disorders have elevated Aβ, tau, dysregulated immune response, and inflammation. In people with DS, Hsa21 genes like APP and DYRK1A are overexpressed, causing an accumulation of amyloid and neurofibrillary tangles, and potentially contributing to an increased risk of AD. As a result, people with DS are a key demographic for research into AD therapeutics and prevention. The molecular links between DS and AD shed insights into the underlying causes of both diseases and highlight potential therapeutic targets. Also, using biomarkers for early diagnosis and treatment monitoring is an active area of research, and genetic screening for high-risk individuals may enable earlier intervention. Finally, the fundamental mechanistic parallels between DS and AD emphasize the necessity for continued research into effective treatments and prevention measures for DS patients at risk for AD. Genetic screening with customized therapy approaches may help the DS population in current clinical studies and future biomarkers.

Maternal fiber-rich diet promotes early-life intestinal development in offspring through milk-derived extracellular vesicles carrying miR-146a-5p

BACKGROUNDS

The intestinal development in early life is profoundly influenced by multiple biological components of breast milk, in which milk-derived extracellular vesicles (mEVs) contain a large amount of vertically transmitted signal from the mother. However, little is known about how maternal fiber-rich diet regulates offspring intestinal development by influencing the mEVs.

RESULTS

In this study, we found that maternal resistant starch (RS) consumption during late gestation and lactation improved the growth and intestinal health of offspring. The mEVs in breast milk are the primary factor driving these beneficial effects, especially enhancing intestinal cell proliferation and migration. To be specific, administration of mEVs after maternal RS intake enhanced intestinal cell proliferation and migration in vivo (performed in mice model and indicated by intestinal histological observation, EdU assay, and the quantification of cyclin proteins) and in vitro (indicated by CCK8, MTT, EdU, and wound healing experiments). Noteworthily, miR-146a-5p was found to be highly expressed in the mEVs from maternal RS group, which also promotes intestinal cell proliferation in cells and mice models. Mechanically, miR-146a-5p target to silence the expression of ubiquitin ligase 3 gene NEDD4L, thereby inhibiting DVL2 ubiquitination, activating the Wnt pathway, and promoting intestinal development.

CONCLUSION

These findings demonstrated the beneficial role of mEVs in the connection between maternal fiber rich diet and offspring intestinal growth. In addition, we identified a novel miRNA-146a-5p-NEDD4L-β-catenin/Wnt signaling axis in regulating early intestinal development. This work provided a new perspective for studying the influence of maternal diet on offspring development.

Application of Milk Exosomes for Musculoskeletal Health: Talking Points in Recent Outcomes

Milk is a nutrient-rich food source, and among the various milks, breast milk is a nutrient source provided by mothers to newborns in many mammals. Exosomes are nano-sized membranous extracellular vesicles that play important roles in cell-to-cell communication. Exosomes originate from endogenous synthesis and dietary sources such as milk. Discovered through electron microscopy as floating vesicles, the existence of exosomes in human milk was confirmed owing to a density between 1.10 and 1.18 g/mL in a sucrose gradient corresponding to the known density of exosomes and detection of MHC classes I and II, CD63, CD81, and CD86 on the vesicles. To date, milk exosomes have been used for treating many diseases, including cancers, and are widely proposed as promising carriers for the delivery of chemotherapeutic agents. However, few studies on milk exosomes focus on geriatric health, especially sarcopenia and osteoporosis related to bone and muscle. Therefore, the present study focused on milk exosomes and their cargoes, which are potential candidates for dietary supplements, and when combined with drugs, they can be effective in treating musculoskeletal diseases. In this review, we introduce the basic concepts, including the definition, various sources, and cargoes of milk exosomes, and exosome isolation and characterization methods. Additionally, we review recent literature on the musculoskeletal system and milk exosomes. Since inflammation and oxidative stress underly musculoskeletal disorders, studies reporting the antioxidant and anti-inflammatory properties of milk exosomes are also summarized. Finally, the therapeutic potential of milk exosomes in targeting muscle and bone health is proposed.

Multifunctional Milk-Derived Small Extracellular Vesicles and Their Biomedical Applications

In recent years, small extracellular vesicles (sEVs) have been regarded as the next generation of novel delivery systems after lipid nanoparticles because of their advantages and huge prospects in drug delivery. Studies have shown that sEVs are abundant in milk and therefore can be a large and economical source of sEVs. Natural milk-derived small extracellular vesicles (msEVs) have important functions such as immune regulation, anti-bacterial infection, anti-oxidative, etc., and play a beneficial role in human health at multiple levels, including intestinal health, bone/muscle metabolism, and microbiota regulation. In addition, because they can pass the gastrointestinal barrier and have low immunogenicity, good biocompatibility, and stability, msEVs are considered a crucial oral drug delivery vehicle. Moreover, msEVs can be further engineered for targeted delivery to prolong the circulation time or enhance local drug concentrations. However, msEVs separation and purification, complex contents, and quality control hinder their application in drug delivery. This paper provides a comprehensive review of the biogenesis and characteristics, isolation and purification, composition, loading methods, and function of msEVs, based on which their applications in biomedical fields are further explored.

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.

Small Extracellular Vesicles in Milk Cross the Blood-Brain Barrier in Murine Cerebral Cortex Endothelial Cells and Promote Dendritic Complexity in the Hippocampus and Brain Function in C57BL/6J Mice

Human milk contains large amounts of small extracellular vesicles (sEVs) and their microRNA cargos, whereas infant formulas contain only trace amounts of sEVs and microRNAs. We assessed the transport of sEVs across the blood-brain barrier (BBB) and sEV accumulation in distinct regions of the brain in brain endothelial cells and suckling mice. We further assessed sEV-dependent gene expression profiles and effects on the dendritic complexity of hippocampal granule cells and phenotypes of EV depletion in neonate, juvenile and adult mice. The transfer of sEVs across the BBB was assessed by using fluorophore-labeled bovine sEVs in brain endothelial bEnd.3 monolayers and dual chamber systems, and in wild-type newborn pups fostered to sEV and cargo tracking (ECT) dams that express sEVs labeled with a CD63-eGFP fusion protein for subsequent analysis by serial two-photon tomography and staining with anti-eGFP antibodies. Effects of EVs on gene expression and dendritic architecture of granule cells was analyzed in hippocampi from juvenile mice fed sEV and RNA-depleted (ERD) and sEV and RNA-sufficient (ERS) diets by using RNA-sequencing analysis and Golgi-Cox staining followed by integrated neuronal tracing and morphological analysis of neuronal dendrites, respectively. Spatial learning and severity of kainic acid-induced seizures were assessed in mice fed ERD and ERS diets. bEnd.3 cells internalized sEVs by using a saturable transport mechanism and secreted miR-34a across the basal membrane. sEVs penetrated the entire brain in fostering experiments; major regions of accumulation included the hippocampus, cortex and cerebellum. Two hundred ninety-five genes were differentially expressed in hippocampi from mice fed ERD and ERS diets; high-confidence gene networks included pathways implicated in axon guidance and calcium signaling. Juvenile pups fed the ERD diet had reduced dendritic complexity of dentate granule cells in the hippocampus, scored nine-fold lower in the Barnes maze test of spatial learning and memory, and the severity of seizures was 5-fold higher following kainic acid administration in adult mice fed the ERD diet compared to mice fed the ERS diet. We conclude that sEVs cross the BBB and contribute toward optimal neuronal development, spatial learning and memory, and resistance to kainic acid-induced seizures in mice.

Milk exosomes in nutrition and drug delivery

Exosomes are natural nanoparticles that originate in the endocytic system. Exosomes play an important role in cell-to-cell communication by transferring RNAs, lipids, and proteins from donor cells to recipient cells or by binding to receptors on the recipient cell surface. The concentration of exosomes and the diversity of cargos are high in milk. Exosomes and their cargos resist degradation in the gastrointestinal tract and during processing of milk in dairy plants. They are absorbed and accumulate in tissues following oral administrations, cross the blood-brain barrier, and dietary depletion and supplementation elicit phenotypes. These features have sparked the interest of the nutrition and pharmacology communities for exploring milk exosomes as novel bioactive food compounds and for delivering drugs to diseased tissues. This review discusses the current knowledgebase, uncertainties, and controversies in these lines of scholarly endeavor and health research.