Quantitative assessment of lipophilic membrane dye-based labelling of extracellular vesicles by nano-flow cytometry

The fluorescence mKate2 labeling as a visualizing system for monitoring small extracellular vesicles

Small extracellular vesicles (sEVs) are nanosized vesicles enclosed in a lipid membrane released by nearly all cell types. sEVs have been considered as reliable biomarkers for diagnostics and effective carriers. Despite the clear importance of sEV functionality, sEV research faces challenges imposed by the small size and precise imaging of sEVs. Recent advances in live and high-resolution microscopy, combined with efficient labeling strategies, enable us to investigate the composition and behavior of EVs within living organisms. Here, a modified sEVs was generated with a near infrared fluorescence protein mKate2 using a VSVG viral pseudotyping-based approach for monitoring sEVs. An observed was made that the mKate2-tagged protein can be incorporated into the membranes of sEVs without altering their physical properties. In vivo imaging demonstrates that sEVs labeled with mKate2 exhibit excellent brightness and high photostability, allowing the acquisition of long-term investigation comparable to those achieved with mCherry labeling. Importantly, the mKate2-tagged sEVs show a low toxicity and exhibit a favorable safety profile. Furthermore, the co-expression of mKate2 and rabies virus glycoprotein (RVG) peptide on sEVs enables brain-targeted visualization, suggesting the mKate2 tag does not alter the biodistribution of sEVs. Together, the study presents the mKate2 tag as an efficient tracker for sEVs to monitor tissue-targeting and biodistribution in vivo.

Extracellular vesicles promote proliferation in an animal model of regeneration

Extracellular vesicles (EVs) are secreted nanoparticles composed of a lipid bilayer that carry lipid, protein, and nucleic acid cargo between cells as a mode of intercellular communication. Although EVs can promote tissue repair in mammals, their roles in animals with greater regenerative capacity are not well understood. Planarian flatworms are capable of whole body regeneration due to pluripotent somatic stem cells called neoblasts that proliferate in response to injury. Here, using transmission electron microscopy, nanoparticle tracking analysis, and protein content examination, we showed that EVs enriched from the tissues of the planarian Schmidtea mediterranea had similar morphology and size as other eukaryotic EVs, and that these EVs carried orthologs of the conserved EV biogenesis regulators ALIX and TSG101. PKH67-labeled EVs were taken up more quickly by S/G2 neoblasts than G1 neoblasts/early progeny and differentiated cells. When injected into living planarians, EVs from regenerating tissue fragments enhanced upregulation of neoblast-associated transcripts. In addition, EV injection increased the number of F-ara-EdU-labelled cells by 49% as compared to buffer injection only. Our findings demonstrate that regenerating planarians produce EVs that promote stem cell proliferation, and suggest the planarian as an amenable in vivo model for the study of EV function during regeneration.

Extracellular vesicles as carriers of mRNA: Opportunities and challenges in diagnosis and treatment

Extracellular vesicles (EVs) are produced by all cells in the body. These biological nanoparticles facilitate cellular communication through the transport of diverse cargoes, including small molecules, proteins, and nucleic acids. mRNA cargoes have gained particular interest given their role in the translation of functional proteins. As a biomarker platform, EVs can be found in nearly all biofluids-blood, mucus, urine, cerebrospinal fluid, and saliva-providing real-time insight into parent cell and tissue function. mRNAs carried by EVs are protected from degradation, resulting in improved detection compared to free mRNA, and recent work demonstrates promising results in using these mRNA cargoes as biomarkers for cancer, neurological diseases, infectious diseases, and gynecologic and obstetric outcomes. Furthermore, given the innate cargo carrying, targeting, and barrier crossing abilities of EVs, these structures have been proposed as therapeutic carriers of mRNA. Recent advances demonstrate methods for loading mRNAs into EVs for a range of disease indications. Here, we review recent studies using EVs and their mRNA cargoes as diagnostics and therapeutics. We discuss challenges associated with EVs in diagnostic and therapeutic applications and highlight opportunities for future development.

Kaempferia parviflora Extracellular Vesicle Loaded with Clarithromycin for the Treatment of Helicobacter pylori Infection

Purpose

Kaempferia parviflora extracellular vesicles (KPEVs) have been reported as promising nanovesicles for drug delivery. This study aimed to load clarithromycin (CLA) into KPEVs (KPEVS-CLA) and determine the physical properties, drug-releasing efficiency, gastric cell uptake, anti-H. pylori activities, and anti-inflammatory responses in comparison with free CLA and KPEVs.

Methods

The size and surface charge of KPEVs-CLA were evaluated using dynamic light scattering and visualized using a transmission electron microscope. The encapsulation efficiency (EE%), loading capacity (LC%), and drug release of KPEVs-CLA were examined using HPLC. Anti-H. pylori growth and anti-adhesion were evaluated. IL-8 gene expression, NF-κB signaling proteins, and anti-inflammatory profiles were examined using qRT-PCR, Western blotting, and Bio-Plex immunoassay, respectively. Anti-chemotaxis was then examined using a Transwell assay.

Results

KPEVs-CLA were intact and showed a negative surface charge similar to that of KPEVs. However, slightly enlarged KPEVs were observed. CLA was successfully loaded into KPEVs with EE of 93.45% ± 2.43%, LC of 9.3% ± 3.02%. CLA release in the PBS and gastric mimic buffer with Fickian diffusion (n ≤ 0.43) according to Korsmeyer-Peppas kinetic model (R2=0.98). KPEVs-CLA was localized in the gastric cells' cytoplasm and perinuclear region. Anti-H. pylori growth and anti-H. pylori adhesion of KPEVs-CLA were compared with those of free CLA with no cytotoxicity to adenocarcinoma gastric cells. KPEVs-CLA significantly reduced IL-8, G-CSF, MIP-1α, and MIP-1β levels. Moreover, KPEVs-CLA showed a superior effect over CLA in reducing G-CSF, MIP-1α, and NF-κB phosphorylation and monocyte chemotactic activities.

Conclusion

KPEVs serve as potential carriers of CLA. They exhibited a higher efficiency in inhibiting gastric cell inflammation mediated by H. pylori infection than free CLA. The establishment of KPEVs-CLA as a nanodrug delivery model for H. pylori treatment could be applied to other plant extracellular vesicles or loaded with other cancer drugs for gastric cancer treatment.

Dynamic and Label-Free Sensing of Cardiomyocyte Responses to Nanosized Vesicles for Cardiac Oxidative Stress Injury Therapy

Cardiac oxidative stress is a significant phenotype of myocardial infarction disease, a leading cause of global health threat. There is an urgent need to develop innovative therapies. Nanosized extracellular vesicle (nEV)-based therapy shows promise, yet real-time monitoring of cardiomyocyte responses to nEVs remains a challenge. In this study, a dynamic and label-free cardiomyocyte biosensing system using microelectrode arrays (MEAs) was constructed. Cardiomyocytes were cultured on MEA devices for electrophysiological signal detection and treated with nEVs from E. coli, gardenia, HEK293 cells, and mesenchymal stem cells (MSC), respectively. E. coli-nEVs and gardenia-nEVs induced severe paroxysmal fibrillation, revealing distinct biochemical communication compared to MSC-nEVs. Principal component analysis identified variations and correlations between nEV types. MSC-nEVs enhanced recovery without inducing arrhythmias in a H2O2-induced oxidative stress injury model. This study establishes a fundamental platform for assessing biochemical communication between nEVs and cardiomyocytes, offering new avenues for understanding nEVs' functions in the cardiovascular system.