Oral Administration Properties Evaluation of Three Milk-derived Extracellular Vesicles Based on Ultracentrifugation Extraction Methods

Milk-derived extracellular vesicles (M-EVs) are low-cost, can be prepared in large quantities, and can cross the gastrointestinal barrier for oral administration. However, the composition of milk is complex, and M-EVs obtained by different extraction methods may affect their oral delivery. Based on this, we propose a new method for extracting M-EVs based on cryogenic freezing treatment (Cryo-M-EVs) and compare this method with the previously reported acetic acid treatment (Acid-M-EVs) method and the conventional ultracentrifugation method (Ulltr-M-EVs). The new method simplifies the pretreatment step and achieves 25-fold and 2-fold higher yields than Acid-M-EVs and Ulltr-M-EVs. And it was interesting to note that Cryo-M-EVs and Acid-M-EVs had higher cellular uptake efficiency, and Cryo-M-EVs presented the best transepithelial transport effect. After oral administration of the three M-EVs extracted by three methods in mice, Cryo-M-EVs effectively successfully crossed the gastrointestinal barrier and achieved hepatic accumulation, whereas Acid-M-EVs and Ultr-M-EVs mostly resided in the intestine. The M-EVs obtained by the three extraction methods showed a favorable safety profile at the cellular as well as animal level. Therefore, when M-EVs obtained by different extraction methods are used for oral drug delivery, we can utilize their accumulation properties at different sites to better deal with different diseases. This article is protected by copyright. All rights reserved.

Isolation and usage of exosomes in central nervous system diseases

BACKGROUND

Exosomes are vesicles secreted by all types of mammalian cells. They are characterized by a double-layered lipid membrane structure. They serve as carriers for a plethora of signal molecules, including DNA, RNA, proteins, and lipids. Their unique capability of effortlessly crossing the blood-brain barrier underscores their critical role in the progression of various neurological disorders. This includes, but is not limited to, diseases such as Alzheimer's, Parkinson's, and ischemic stroke. Establishing stable and mature methods for isolating exosomes is a prerequisite for the study of exosomes and their biomedical significance. The extraction technologies of exosomes include differential centrifugation, density gradient centrifugation, size exclusion chromatography, ultrafiltration, polymer coprecipitation, immunoaffinity capture, microfluidic, and so forth. Each extraction technology has its own advantages and disadvantages, and the extraction standards of exosomes have not been unified internationally.

AIMS

This review aimed to showcase the recent advancements in exosome isolation techniques and thoroughly compare the advantages and disadvantages of different methods. Furthermore, the significant research progress made in using exosomes for diagnosing and treating central nervous system (CNS) diseases has been emphasized.

CONCLUSION

The varying isolation methods result in differences in the concentration, purity, and size of exosomes. The efficient separation of exosomes facilitates their widespread application, particularly in the diagnosis and treatment of CNS diseases.

Evaluation and validation of laboratory procedures for the surveillance of ESBL-, AmpC-, and carbapenemase-producing Escherichia coli from fresh meat and caecal samples

Introduction

Extended-spectrum β-lactamase- (ESBL) and AmpC- β-lactamase-producing Enterobacterales are widely distributed and emerging in both human and animal reservoirs worldwide. A growing concern has emerged in Europe following the appearance of carbapenemase-producing Escherichia coli (E. coli) in the primary production of food animals. In 2013, the European Commission (EC) issued the Implementing Decision on the monitoring and reporting of antimicrobial resistance in zoonotic and commensal bacteria. The European Union Reference Laboratory for Antimicrobial Resistance (EURL-AR) was tasked with providing two laboratory protocols for samples derived from meat and caecal content, respectively, for the isolation of ESBL- and AmpC-producing E. coli (part 1) and carbapenemase-producing (CP) E. coli (part 2). In this study, we describe the current protocols, including the preparatory work for the development.

Methods

Up to nine laboratory procedures were tested using minced meat as the matrix from beef, pork, and chicken as well as six procedures for the caecal content of cattle, pigs, and chicken. Variables included sample volume, pre-enrichment volume, pre-enrichment broth with and without antimicrobial supplementation, and incubation time/temperature. The procedures were evaluated against up to nine E. coli strains harboring different AMR genes and belonging to the three β-lactamase groups.

Results and discussion

The laboratory procedures tested revealed that the most sensitive and specific methodologies were based on a Buffered Peptone Water pre-enrichment of 225 ml to 25 g or 9 ml to 1 g for minced meat and caecal content, respectively, incubated at 37°C overnight, followed by inoculation onto MacConkey agar supplemented with 1 mg/L cefotaxime for detecting ESBL- and AmpC-producing E. coli and Chrom ID SMART (Chrom ID CARBA and OXA) for CP E. coli, incubated overnight at 37 and 44°C, respectively. We provided two isolation protocols for the EU-specific monitoring of ESBL- and AmpC- producing E. coli (part 1) and CP E. coli (part 2) from fresh meat (protocol 1) and caecal (protocol 2) samples, which have been successfully implemented by all EU Member States for the monitoring period 2014-2027 (EU 2020/1729).

Activation of Inflammation by MCF-7 Cells-Derived Small Extracellular Vesicles (sEV): Comparison of Three Different Isolation Methods of sEV

PURPOSE

Small extracellular vesicles (sEV) containing proteins and RNAs play important roles as intercellular signal mediators. A critical issue is that there are multiple methods to prepare sEV fractions. The purpose of this study was to examine whether cancer cell-derived sEV fractions prepared by different isolation methods show similar responses for the induction of inflammatory cytokines in macrophages.

METHODS

sEV fractions from the conditioned medium of MCF-7 cells were prepared by ultracentrifugation (UC), the MagCapture Exosome Isolation Kit PS (PS), or the ExoQuick-TC kit (EQ). The mRNA levels of inflammatory cytokines in differentiated THP-1 cells treated with the sEV fractions were evaluated.

RESULTS

The yields of sEV fractions obtained from 1 mL conditioned medium by UC, PS, or EQ were 3.2×10⁸ particles (0.27 μg protein), 12.8×10⁸ particles (0.87 μg protein) and 23.5 ×10⁸ particles (4.50 μg protein), respectively. The average particle sizes in the UC, PS, and EQ fractions were 184.8 ± 1.8 nm, 157.8 ± 1.3 nm and 165.8 ± 1.1 nm, respectively. CD9 and CD81, markers of sEV, were most highly detected in the PS fraction, followed by the EQ and UC fractions. These results suggest that PS gave sEV with relatively high purity, and many protein contaminants appear to be included in the EQ fraction. The mRNA levels of inflammatory cytokines in THP-1 macrophages were most prominently increased by treatment with the UC fraction, followed by the EQ and PS fractions, suggesting that contaminants rather than sEV may largely induce an inflammatory response.

CONCLUSION

The isolation method affects the evaluation of sEV function.

Conceptual Design of the "Private Car" Self-Isolation Ecosystem for the 2019-nCoV Infection

Since the beginning of the COVID-19 outbreak, confirmed and suspected cases of the disease have been increasing rapidly. The isolation of cases is one of the most effective methods for the control and containment of COVID-19 and has been rapidly popularized. Problems with isolation have gradually emerged, such as the inadequate allocation of isolation resources and the failure to properly resettle many of the suspected cases of the 2019-nCoV infection. In this paper, a self-isolation ecosystem of a rapid-deploying negative-pressurized "private car" is proposed for housing patients with 2019-nCoV infection, which could be lightweight, moderately sized and transparent to enable group supervision and communication. This "private car" isolation method aims to achieve self-isolation of patients and essentially solves the problem of where and how to isolate suspected cases while saving isolation resources and preventing the large-scale transmission of COVID-19.

Proposal of a novel selective enrichment broth, NCT-mTSB, for isolation of Escherichia albertii from poultry samples

AIMS

Escherichia albertii is an emerging diarrheagenic pathogen causing food- and water-borne infection in humans. However, no selective enrichment broths for E. albertii have ever been reported. In this study, we tested several basal media, selective supplements and culture conditions which enabled selective enrichment of E. albertii.

METHODS AND RESULTS

We developed a selective enrichment broth, novobiocin-cefixime-tellurite supplemented modified tryptic soy broth (NCT-mTSB). NCT-mTSB supported the growth of 22 E. albertii strains, while inhibited growth of other Enterobacteriaceae at 37°C, except for Escherichia coli and Shigella spp. Enrichment of E. albertii was improved further by growth at 44°C, a temperature that suppresses growth of several strains of E. coli/Shigella. Combined use of NCT-mTSB with XR-DH-agar, xylose-rhamnose supplemented deoxycholate hydrogen sulphide agar, enabled isolation of E. albertii when at least 1 CFU of the bacterium was present per gram of chicken meat. This level of enrichment was superior to those obtained using buffered peptone water, modified-EC broth, or mTSB (with novobiocin).

CONCLUSIONS

Novobiocin-cefixime-tellurite supplemented modified tryptic soy broth enabled effective enrichment of E. albertii from poultry samples and was helpful for isolation of this bacterium.

SIGNIFICANCE AND IMPACT OF STUDY

To our knowledge, this is the first report of selective enrichment of E. albertii from poultry samples.

Effect of Isolation Conditions on Diversity of Endolichenic Fungal Communities from a Foliose Lichen, Parmotrema tinctorum

Endolichenic fungi (ELF) are emerging novel bioresources because their diverse secondary metabolites have a wide range of biological activities. Metagenomic analysis of lichen thalli demonstrated that the conventional isolation method of ELF covers a very limited range of ELF, and the development of an advanced isolation method is needed. The influence of four variables were investigated in this study to determine the suitable conditions for the isolation of more diverse ELF from a radially growing foliose lichen, Parmotrema tinctorum. Four variables were tested: age of the thallus, severity of surface-sterilization of the thallus, size of a thallus fragment for the inoculation, and nutrient requirement. In total, 104 species (1885 strains) of ELF were isolated from the five individual thalli of P. tinctorum collected at five different places. Most of the ELF isolates belong to Sordariomycetes. Because each part of lichen thallus (of different age) has unique ELF species, the whole thallus of the foliose lichen is needed to isolate diverse ELF. Moderate sterilization is appropriate for the isolation of diverse ELF. Inoculation of small fragment (1 mm²) of lichen thallus resulted in the isolation of highest diversity of ELF species compared to larger fragments (100 and 25 mm²). Moreover, ELF species isolated from the small thallus fragments covered all ELF taxa detected from the medium and the large fragments in this study. The use of two media—Bold’s basal medium (nutrient poor) and potato dextrose agar (nutrient rich)—supported the isolation of diverse ELF. Among the tested variables, size of thallus fragment more significantly influenced the isolation of diverse ELF than other three factors. Species composition and richness of ELF communities from different lichen thalli differed from each other in this study.

Research Note: A baseline survey of thermotolerant Campylobacter in retail chicken in southern Brazil

Chicken is a leading source of thermotolerant Campylobacter, which triggers human foodborne enteritis. This study evaluated thermotolerant Campylobacter contamination of retail chicken in southern Brazil, using qualitative and quantitative analyses. Selective enrichment in Bolton broth for 24 and 48 h after plating onto modified charcoal-cefoperazone-deoxycholate (mCCD) agar and Preston agar was assessed. The combined results of the detection and enumeration methods revealed a frequency of 70% occurrence of thermotolerant Campylobacter in chicken samples. Campylobacter was enumerated in 60% of the samples, whereas 46% of the samples were positive in the qualitative analysis. Quantitative analysis showed average counts of 3.10 ± 0.15 log₁₀ CFU/sample. Higher numbers of Campylobacter-positive samples were found using 24-h enrichment before plating onto Preston agar (46%) than onto mCCD agar (2%). The majority of isolated strains were identified as Campylobacter jejuni, and Campylobacter coli was also found but to a lesser extent. Subtyping revealed a clear distinction between strains isolated from different chicken sources. The enriched samples plated onto mCCD agar showed extensive spreading of nonproducing extended-spectrum β-lactamases Proteus mirabilis that hampered the identification of Campylobacter colonies. P. mirabilis strains showed resistance to cefoperazone, trimethoprim, and polymyxin B present in broth and plate media used and were inhibited by rifampicin present in Preston agar. The results underline the effect of the spread of contaminant strains on Campylobacter cultures, which might be prevented using a recently revised International Organization for Standardization method for qualitative analysis of chicken.

[Advances in separation techniques for exosomes and their clinical applications]

Exosomes are vesicles secreted by many types of cells through exocytosis, and their sizes range from 30 to 200 nm. Exosomes consist of a lipid bilayer membrane, containing a number of bioactive molecules, e. g., proteins, ribose nucleic acid (RNA), and deoxyribo nucleic acid (DNA) derived from the cell of origin. As intercellular communication carriers, exosomes participate in many physiological and pathological processes. Because of the complexity of body fluids, as well as the small size and low density of exosomes, the isolation of exosomes is an essential and challenging step before subsequent analysis and functional studies. This review summarizes the advances in the analytical approaches, characterization methods, biological functions and clinical applications of exosomes, with particular emphasis on exosomes isolation techniques.

Metabolism of 4-pyridone-3-carboxamide-1β-d-ribonucleoside (4PYR) in primary murine brain microvascular endothelial cells (mBMECs)

4-pyridone-3-carboxamide-1β-D-ribonucleoside (4PYR) is a derivative of nicotinamide found physiologically in human body fluids that can be metabolized to mono-, di- or triphosphate derivatives (4PYMP, 4PYDP and 4PYTP respectively) and an analogue of NAD - the 1-β-D-ribonucleoside-4-pyridone-3-carboxamide adenine dinucleotide (4PYRAD) in human cells. The European Uremic Toxin Work Group (EUTox) has classified 4PYR as a uremic toxin that adversely affects endothelium. This study aimed to investigate the metabolism of 4PYR in murine brain microvascular endothelial cells (mBMECs). Incubation of mBMECs with 4PYR was carried out for 0, 24, 48 or 72 h. After incubation, a medium was removed and cellular concentrations of ATP, ADP, NAD, 4PYMP and 4PYRAD were analyzed using reversed-phase HPLC. 4PYR was metabolized by mBMECs to 4PYMP and 4PYRAD that reached concentrations of 2 ± 0.7 and 0.6 ± 0.2 nmol/mg protein (mean ± SEM), respectively, after 72 h incubation. However, unlike with endothelial cells studied so far this process has no effect on energy balance in the cell as indicated by maintained ATP/ADP ratio and adenine and nicotinamide intracellular pools. Further studies are required to explain whether the difference in 4PYR metabolism is related to differences between species or organs.

Widespread distribution of mcr-1-bearing bacteria in the ecosystem, 2015 to 2016

The recently discovered colistin resistance-encoding element, mcr-1, adds to the list of mobile resistance genes whose products rapidly erode the antimicrobial efficacy of not only the commonly used antibiotics, but also the last line agents of carbapenems and colistin. The relative prevalence of mcr-1-bearing strains in various ecological niches including 1,371 food samples, 480 animal faecal samples, 150 human faecal samples and 34 water samples was surveyed using a novel in-house method. Bacteria bearing mcr-1 were commonly detected in water (71% of samples), animal faeces (51%), food products (36%), and exhibited stable carriage in 28% of human subjects surveyed. Such strains, which exhibited variable antibiotic susceptibility profiles, belonged to various Enterobacteriaceae species, with Escherichia coli being the most dominant in each specimen type. The mcr-1 gene was detectable in the chromosome as well as plasmids of various sizes. Among these, two conjugative plasmids of sizes ca 33 and ca 60 kb were found to be the key vectors that mediated mcr-1 transmission in organisms residing in various ecological niches. The high mcr-1 carriage rate in humans found in this study highlights the importance of continued vigilance, careful antibiotic stewardship, and the development of new antimicrobials.

An adapted isolation procedure reveals Photobacterium spp. as common spoilers on modified atmosphere packaged meats

The genus Photobacterium comprises species of marine bacteria, commonly found in open-ocean and deep-sea environments. Some species (e.g. Photobacterium phosphoreum) are associated with fish spoilage. Recently, culture-independent studies have drawn attention to the presence of photobacteria on meat. This study employed a comparative isolation approach of Photobacterium spp. and aimed to develop an adapted isolation procedure for recovery from food samples, as demonstrated for different meats: Marine broth is used for resuspending and dilution of food samples, followed by aerobic cultivation on marine broth agar supplemented with meat extract and vancomycin at 15°C for 72 h. Identification of spoilage-associated microbiota was carried out via Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry using a database supplemented with additional mass spectrometry profiles of Photobacterium spp. This study provides evidence for the common abundance of multiple Photobacterium species in relevant quantities on various modified atmosphere packaged meats. Photobacterium carnosum was predominant on beef and chicken, while Photobacterium iliopiscarium represented the major species on pork and Photobacterium phosphoreum on salmon, respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates highly frequent isolation of multiple photobacteria (Photobacterium carnosum, Photobacterium phosphoreum, and Photobacterium iliopiscarium) from different modified-atmosphere packaged spoiled and unspoiled meats using an adapted isolation procedure. The abundance of photobacteria in high numbers provides evidence for the hitherto neglected importance and relevance of Photobacterium spp. to meat spoilage.

Methods for Baiting and Enriching Fungus-Feeding (Mycophagous) Rhizosphere Bacteria

Mycophagous soil bacteria are able to obtain nutrients from living fungal hyphae. However, with exception of the soil bacterial genus Collimonas, occurrence of this feeding strategy has not been well examined. Evaluation of the importance of mycophagy in soil bacterial communities requires targeted isolation methods. In this study, we compared two different approaches to obtain mycophagous bacteria from rhizospheric soil. A short-term method based on baiting for bacteria that can rapidly adhere to fungal hyphae and a long-term method based on the enrichment of bacteria on fungal hyphae via repeated transfer. Hyphae-adhering bacteria were isolated, identified by 16S rDNA sequencing and tested for antifungal activity and the ability to feed on fungi as the sole source of carbon. Both methods yielded a range of potentially mycophagous bacterial isolates with little phylogenetic overlap. We also found indications for feeding preferences among the potentially mycophagous bacteria. Our results indicate that mycophagy could be an important growth strategy for rhizosphere bacteria. To our surprise, we found several potential plant pathogenic bacteria among the mycophagous isolates. We discuss the possible benefits that these bacteria might gain from colonizing fungal hyphae.

Characterization of progenitor cells and stem cells from the periodontal ligament tissue derived from a single person

BACKGROUND

Periodontal ligament progenitor cells (PDLPs) and PDL stem cells (PDLSCs) are progenitor and stem cells that were isolated from PDL tissues using the outgrowth and single cell isolation methods respectively. The differences between PDLPs and PDLSCs characteristics could be observed from previous studies. However, these cells were obtained from different patients. This study was the first report to compare the characterization of PDLPs and PDLSCs from the same person.

MATERIAL AND METHODS

The characterization of PDLPs and PDLSCs includes flow cytometry analysis, cell proliferation assay and the assessment of the colony-forming unit fibroblast. The osteogenic differentiation was evaluated by alkaline phosphatase activity, biomineralization (alizarin red staining) and gene expression of osteogenic markers. The adipogenic differentiation was examined by Oil Red O staining and adipocyte-related gene expression.

RESULTS

Mesenchymal stem cell marker expression and colony-forming unit fibroblast analysis of PDLPs and PDLSCs were similar. However, PDLSCs grew faster than PDLPs on days 3 and 5 of the cell proliferation assay. Both PDLPs and PDLSCs could differentiate into osteoblast and adipocyte-like cells. However, the mineralization of PDLSCs was stronger than that of PDLPs.

CONCLUSIONS

The characteristics of undifferentiated PDL cells in our study were not significantly impacted by the isolation method. We assumed that both PDLPs and PDLSCs are valuable cell sources for periodontal regeneration. However, PDLSCs have a possible advantage for the regeneration of alveolar bone.

The effect of different isolation protocols on detection and molecular characterization of Campylobacter from poultry

We determined whether different methods to isolate Campylobacter (including the ISO standard 10272:2006-1) affected the genotypes detectable from poultry, at three points during slaughter: caecal content, neck skin and meat. Carcasses from 28 independent flocks were thus sampled (subset A). In addition, ten neck skin samples from four flocks, ten caecal samples from ten different flocks and ten unrelated meat samples obtained from local supermarkets were collected (subset B). Campylobacter was isolated using eight different protocols: with and without enrichment using Bolton broth, Preston broth or Campyfood broth (CFB), followed by culture on either modified Charcoal Cefoperazone Deoxycholate Agar (mCCDA) or Campyfood agar (CFA). All obtained isolates were genotyped for flaA-SVR, and over half of the isolates were also typed by MLST. The strain richness, as a measure of number of detected fla-genotypes, obtained from subset A neck skin and caecal samples was higher than that of meat samples. In half of the cases, within a flock, at least one identical fla-genotype was obtained at all three slaughter stages, suggestive of autologous contamination of carcasses. Enrichment reduced the observed richness of isolates, while CFA plates increased richness compared to mCCDA plates, irrespective of inclusion of an enrichment step. Because the isolation protocol used influences both the yield and the fla-genotype richness obtained from poultry, this variable should be taken into account when different studies are being compared.

Cellulose Isolation Methodology for NMR Analysis of Cellulose Ultrastructure

In order to obtain accurate information about the ultrastructure of cellulose from native biomass by ¹³C cross polarization magic angle spinning (CP/MAS) NMR spectroscopy the cellulose component must be isolated due to overlapping resonances from both lignin and hemicellulose. Typically, cellulose isolation has been achieved via holocellulose pulping to remove lignin followed by an acid hydrolysis procedure to remove the hemicellulose components. Using ¹³C CP/MAS NMR and non-linear line-fitting of the cellulose C₄ region, it was observed that the standard acid hydrolysis procedure caused an apparent increase in crystallinity of ~10% or less on the cellulose isolated from Populus holocellulose. We have examined the effect of the cellulose isolation method, particularly the acid treatment time for hemicellulose removal, on cellulose ultrastructural characteristics by studying these effects on cotton, microcrystalline cellulose (MCC) and holocellulose pulped Populus. ¹³C CP/MAS NMR of MCC indicated that holocellulose pulping and acid hydrolysis has little effect on the crystalline ultrastructural components of cellulose. Although any chemical method to isolate cellulose from native biomass will invariably alter substrate characteristics, especially those related to regions accessible to solvents, we found those changes to be minimal and consistent in samples of typical crystallinity and lignin/hemicellulose content. Based on the rate of the hemicellulose removal, as determined by HPLC-carbohydrate analysis and magnitude of cellulose ultrastructural alteration, the most suitable cellulose isolation methodology utilizes a treatment of 2.5 M HCl at 100 °C for a standard residence time between 1.5 and 4 h. However, for the most accurate crystallinity results this residence time should be determined empirically for a particular sample.