Project description:Extracellular vesicles that are derived from stem cells play an important role in the treatment of disease. To obtain high-quality small extracellular vesicles (sEVs), we optimized the culture conditions of human induced pluripotent stem cells (hiPSCs), the supernatant collection time, and sEVs extraction methods. Firstly, hiPSCs were cultured in extracellular vesicles-production medium (EVs-PM) containing different concentrations (0%, 0.25%, 0.5%, 2%, 5%, and 20%) of extracellular vesicle-depleted knockout serum replacement (ED-KSR), and the culture supernatants were collected continuously for 5 days. Then, the sEVs were isolated, followed by an evaluation of their characteristics. The survival rates of the hiPSCs lines that were cultured in EVs-PM containing 0.5% to 20% ED-KSR were not significantly different (P > 0.05). The survival rates of the hiPSCs in 0.5% ED-KSR after the culture supernatants were continuously collected for day 1, day 3, and day 5 were not statistically significant (P > 0.05). After 5 days of continuous collection of the supernatant, the hiPSCs expressed some pluripotent markers, while SSEA4 and TRA-1-60 expression changed gradually. The sEVs that were extracted by the two methods were all 50-200 nm, double-layered and oval or round cellular vesicles and expressed the marker proteins CD63, TSG101, and HSP70. The characteristics of sEVs extracted on day 1, day 3, and day 5 were almost identical on morphology, size and the relative quantity of annexin V-positive subpopulations. The PKH67 staining showed that the sEVs could be endocytosed by HepG2 cells and aggregated in the cytoplasm. The proliferation experiments showed that the sEVs can promote cell proliferation. In Conclusion, the 0.5% ED-KSR is the optimal concentration, and that the hiPSCs culture supernatant can be continuously collected for 5 days while maintaining high cell viability and some pluripotent characteristics. Both of the methods extraction can be used to obtain biologically active sEVs.
Project description:Background: Extracellular vesicles (EVs) were reported to participate in various cellular processes based on the biomolecules, particularly microRNAs. Numerous commercial EVs isolation reagents are available. However, whether these reagents are suitable for separating EVs from the culture medium supernatant supernatant of model cell lines, such as HepG2, and whether the isolated products are suitable for High-throughput sequencing remains unclear. Methods: We examined three commonly used EVs isolation kits: the ExoQuick-TC exosome precipitation solution (EQ), Total Exosome Isolation from cell culture medium (EI), and exoEasy Maxi Kit (EM), to isolate EVs from HepG2 cell culture medium supernatants. EVs were identified based on marker proteins, particle size measurements, and electron microscopy analysis. The total amounts of microRNA and microRNA High-throughput sequencing data quality from EVs isolated by each kit were compared. Results: The total amount of EVs' microRNA isolated from the EI and EM groups were higher than that obtained from the EQ group (EQ/EI: p = 0.036, EI/EM: p = 0.024). High-throughput sequencing data quality evaluation showed that the EI group possessed higher quality than those in the EM group. Conclusion: For the cell culture medium from HepG2, EVs' microRNA isolated by EI reagents might be more suitable for High-throughput sequencing applications.
Project description:Extracellular vesicles (EVs) are nano-sized vesicles containing nucleic acid and protein cargo that are released from a multitude of cell types and have gained significant interest as potential diagnostic biomarkers. Human serum is a rich source of readily accessible EVs; however, the separation of EVs from serum proteins and non-EV lipid particles represents a considerable challenge. In this study, we compared the most commonly used isolation techniques, either alone or in combination, for the isolation of EVs from 200 µl of human serum and their separation from non-EV protein and lipid particles present in serum. The size and yield of particles isolated by each method was determined by nanoparticle tracking analysis, with the variation in particle size distribution being used to determine the relative impact of lipoproteins and protein aggregates on the isolated EV population. Purification of EVs from soluble protein was determined by calculating the ratio of EV particle count to protein concentration. Finally, lipoprotein particles co-isolated with EVs was determined by Western blot analysis of lipoprotein markers APOB and APOE. Overall, this study reveals that the choice of EV isolation procedure significantly impacts EV yield from human serum, together with the presence of lipoprotein and protein contaminants.
Project description:Cytotoxic T lymphocytes (CTLs) kill infected and cancerous cells. We detected transfer of cytotoxic multiprotein complexes, called supramolecular attack particles (SMAPs), from CTLs to target cells. SMAPs were rapidly released from CTLs and were autonomously cytotoxic. Mass spectrometry, immunochemical analysis, and CRISPR editing identified a carboxyl-terminal fragment of thrombospondin-1 as an unexpected SMAP component that contributed to target killing. Direct stochastic optical reconstruction microscopy resolved a cytotoxic core surrounded by a thrombospondin-1 shell of ~120 nanometer diameter. Cryo-soft x-ray tomography analysis revealed that SMAPs had a carbon-dense shell and were stored in multicore granules. We propose that SMAPs are autonomous extracellular killing entities that deliver cytotoxic cargo targeted by the specificity of shell components.
Project description:Extracellular vesicles (EVs) have attracted interest due to their ability to provide diagnostic information from liquid biopsies. Cells constantly release vesicles divers in size, content and features depending on the biogenesis, origin and function. This heterogeneity adds a layer of complexity when attempting to isolate and characterize EVs resulting in various protocols. Their high abundance in all bodily fluids and their stable source of origin dependent biomarkers make EVs a powerful tool in biomarker discovery and diagnostics. However, applications are limited by the quality of samples definition. Here, we compared frequently used isolation techniques: ultracentrifugation, density gradient centrifugation, ultrafiltration and size exclusion chromatography. Then, we aimed for a tissue-specific isolation of prostate-derived EVs from cell culture supernatants with immunomagnetic beads. Quality and quantity of EVs were confirmed by nanoparticle tracking analysis, western blot and electron microscopy. Additionally, a spotted antibody microarray was developed to characterize EV sub-populations. Current analysis of 16 samples on one microarray for 6 different EV surface markers in triplicate could be easily extended allowing a faster and more economical method to characterize samples.
Project description:Cytotoxic attack particles released by CTLs and NK cells include diverse phospholipid membrane and glycoprotein encapsulated entities that contribute to target cell killing. Supramolecular attack particles (SMAPs) are one type of particle characterized by a cytotoxic core enriched in granzymes and perforin surrounded by a proteinaceous shell including thrombospondin (TSP)-1. TSP-4 was also detected in bulk analysis of SMAPs released by CTLs; however, it has not been investigated whether TSP-4 contributes to distinct SMAP types or the same SMAP type as TSP-1 and, if in the same type of SMAP, whether TSP-4 and TSP-1 cooperate or compete. Here, we observed that TSP-4 expression increased upon CD8+ T cell activation while, surprisingly, TSP-1 was down-regulated. Correlative Light and Electron Microscopy and Stimulated Emission Depletion microscopy localized TSP-4 and TSP-1 in SMAP-containing multicore granules. Superresolution dSTORM revealed that TSP-4 and TSP-1 are usually enriched in the same SMAPs while particles with single-positive shells are rare. Retention Using Selective Hooks assays showed that TSP-4 localizes to the lytic granules faster than TSP-1 and promotes its accumulation therein. TSP-4 contributed to direct CTL-mediated killing, as previously shown for TSP-1. TSP-4 and TSP-1 were both required for latent SMAP-mediated cell killing, in which released SMAPs kill targets after removal of the CTLs. Of note, we found that chronic lymphocytic leukemia (CLL) cell culture supernatants suppressed expression of TSP-4 in CTL and latent SMAP-mediated killing. These results identify TSP-4 as a functionally important component of SMAPs and suggest that SMAPs may be targeted for immune suppression by CLL.
Project description:Extracellular vesicles (EVs) are abundant, lipid-enclosed vectors that contain nucleic acids and proteins, they can be secreted from donor cells and freely circulate, and they can be engulfed by recipient cells thus enabling systemic communication between heterotypic cell types. However, genetic tools for labeling, isolating, and auditing cell type-specific EVs in vivo, without prior in vitro manipulation, are lacking. We have used CRISPR-Cas9-mediated genome editing to generate mice bearing a CD63-emGFPloxP/stop/loxP knock-in cassette that enables the specific labeling of circulating CD63+ vesicles from any cell type when crossed with lineage-specific Cre recombinase driver mice. As proof-of-principle, we have crossed these mice with Cdh5-CreERT2 mice to generate CD63emGFP+ vasculature. Using these mice, we show that developing vasculature is marked with emerald GFP (emGFP) following tamoxifen administration to pregnant females. In adult mice, quiescent vasculature and angiogenic vasculature (in tumors) is also marked with emGFP. Moreover, whole plasma-purified EVs contain a subpopulation of emGFP+ vesicles that are derived from the endothelium, co-express additional EV (e.g., CD9 and CD81) and endothelial cell (e.g., CD105) markers, and they harbor specific miRNAs (e.g., miR-126, miR-30c, and miR-125b). This new mouse strain should be a useful genetic tool for generating cell type-specific, CD63+ EVs that freely circulate in serum and can subsequently be isolated and characterized using standard methodologies.
Project description:As interest in the role of extracellular vesicles in cell-to-cell communication has increased, so has the use of microscopy and analytical techniques to assess their formation, release, and morphology. In this study, we evaluate scanning electron microscopy (SEM) and cryo-SEM for characterizing the formation and shedding of vesicles from human breast cell lines, parental and hyaluronan synthase 3-(HAS3)-overexpressing MCF10A cells, grown directly on transmission electron microscopy (TEM) grids. While cells imaged with conventional and cryo-SEM exhibit distinct morphologies due to the sample preparation process for each technique, tubular structures protruding from the cell surfaces were observed with both approaches. For HAS3-MCF10A cells, vesicles were present along the length of membrane protrusions. Once completely shed from the cells, extracellular vesicles were characterized using nanoparticle tracking analysis (NTA) and cryo-TEM. The size distributions obtained by each technique were different not only in the range of vesicles analyzed, but also in the relative proportion of smaller-to-larger vesicles. These differences are attributed to the presence of biological debris in the media, which is difficult to differentiate from vesicles in NTA. Furthermore, we demonstrate that cryo-TEM can be used to distinguish between vesicles based on their respective surface structures, thereby providing a path to differentiating vesicle subpopulations and identifying their size distributions. Our study emphasizes the necessity of pairing several techniques to characterize extracellular vesicles.
Project description:Extracellular vesicles are commonly found in human body fluids and can reflect current physiological conditions of human body and act as biomarkers of disease. The quality of isolated extracellular vesicles facilitates the early diagnosis of various diseases accompanied by hyperlipidemia. Nonetheless, there are no reports on which special methods are suitable for isolating extracellular vesicles from the plasma of patients with hyperlipidemia. Thus, this study compared three different research-based extracellular vesicle isolation approaches, namely ultracentrifugation (UC), polyethylene glycol (PEG) precipitation, and size exclusion chromatography (SEC), and determined which of them was the most effective method. We selected blood samples from 12 patients with clinically diagnosed hyperlipidemia and isolated plasma-derived extracellular vesicles using three methods. The morphology of the isolated extracellular vesicles was observed using transmission electron microscopy, while the concentration was detected by asymmetric flow field-flow fractionation and multi-angle light scattering. Marker proteins were identified by Western blotting, and protein composition was evaluated by silver staining. Both determined the contaminations in the extracellular vesicle samples. The results showed that the three methods can be successfully used for the isolation of extracellular vesicles. The extracellular vesicles isolated by UC were larger in size, and the yield was much lower. Although the yield of extracellular vesicles isolated by PEG precipitation was greatly improved, the contamination was increased. Of the three methods, only the SEC-isolated extracellular vesicles were characterized by high yield and low contamination. Therefore, our data suggested that the SEC was a more ideal method for isolating extracellular vesicles from the plasma of patients with hyperlipidemia.
Project description:Cytotoxic T lymphocytes (CTL) kill malignant and infected cells through the directed release of cytotoxic proteins into the immunological synapse (IS). The cytotoxic protein granzyme B (GzmB) is released in its soluble form or in supramolecular attack particles (SMAP). We utilize synaptobrevin2-mRFP knock-in mice to isolate fusogenic cytotoxic granules in an unbiased manner and visualize them alone or in degranulating CTLs. We identified two classes of fusion-competent granules, single core granules (SCG) and multi core granules (MCG), with different diameter, morphology and protein composition. Functional analyses demonstrate that both classes of granules fuse with the plasma membrane at the IS. SCG fusion releases soluble GzmB. MCGs can be labelled with the SMAP marker thrombospondin-1 and their fusion releases intact SMAPs. We propose that CTLs use SCG fusion to fill the synaptic cleft with active cytotoxic proteins instantly and parallel MCG fusion to deliver latent SMAPs for delayed killing of refractory targets.