Milk Exosomes: Isolation, Biochemistry, Morphology, and Perspectives of Use

Abstract

Cells of the multicellular organisms communicate with each other in many different ways, among which extracellular vesicles play a unique role. Almost all cell types secrete vesicles into the extracellular space and deliver their contents to recipient cells. Today, one of the groups of extracellular vesicles that is of particular interest for studying is exosomes-membrane vesicles with a diameter of 40-100 nm. Exosomes are secreted by cells and found in various biological fluids-blood, tears, saliva, urine, cerebrospinal fluid, and milk. Exosomes provide not only targeted delivery of molecular signals to recipient cells but also carry unique markers, which makes them a promising substrate in diagnostic studies, primarily due to their small RNA and protein contents. The milk of cows, horses, humans, and other mammals is a unique source of exosomes since these organisms can produce liters of milk per day, which is much higher than the volume of exosomes produced in cell culture fluid or blood plasma. Unfortunately, milk exosomes are currently much less studied than exosomes of blood or culture fluid. This review examines the methods of the isolation, biochemical analysis (composition of proteins, lipids, and nucleic acids), morphology, and prospects for the use of milk exosomes.

Milk Exosomes: Perspective Agents for Anticancer Drug Delivery

“…Gel filtration allows purifying the sample from co-isolating proteins in preparations obtained after ultrafiltration and/or ultracentrifugation. Our data suggest that sequential centrifugations and ultracentrifugations followed by the ultrafiltration throw 0.22 µm filter are not enough to get purified exosomes [ 39 ]. Moreover, gel filtration of sediments obtained by ultracentrifugation results in exosome preparations without admixtures of co-isolating proteins [ 11 ].…”

MicroRNA Milk Exosomes: From Cellular Regulator to Genomic Marker

“…Numerous studies have been reported on milk-derived EXO, of human and laboratory animal origin, with both in vitro and in vivo approaches, but less information is available on the EXO in dairy ruminants. In humans, the molecular composition of milk EXO depends on the physiological status of the mother [2], and largely on her lifestyle, lactation stage and contact with allergens [113].…”

“…Prokaryote and eukaryote cells release extracellular vesicles (EVs) as part of their normal physiology, and as a result of acquired abnormalities [1]. The cells of multicellular organisms use different ways to communicate, including EVs, which play a unique role [2]. A particularly interesting subtype of EVs is exosomes, the research into which is rapidly growing.…”

“…Then, the different contents of exosomes can be delivered to a recipient cell, whose biological response can be effectively altered [1]. In addition, exosomes secreted by cells are found in various biological fluids such as blood, plasma, tears, semen, saliva, urine, cerebrospinal fluid, epididymal fluid, amniotic fluid, tumor ascites, bronchoalveolar lavage fluid, synovial fluid and milk [2,10,11]. As result, exosomes are used as biomarkers for the diagnosis of various diseases [1,12,13].…”

“…In this way, miRNAs control a wide range of cellular functions, such as cell differentiation, organogenesis [24], proliferation and cell death, and regulate several aspects of health and diseases [25,26], fat storage, hematopoiesis and immunity [27]. Authors have reported that miRNAs constitute the majority of the RNA contained in these vesicles [2,28,29]. However, the stoichiometry analysis of miRNAs in exosomes, performed by Chevillet et al [30], indicated that the copy numbers of these molecules are very low, and a reconsideration of the mechanism of exosome-mediated miRNAs communication deserves further investigation.…”