Multivalent Engineering of Exosomes with Activatable Aptamer Probes for Specific Regulation and Monitoring of Cell Targeting

A lateral flow assay strip for simultaneous detection of miRNA and exosomes in liver cancer

By employing an aptamer as the bridge and combining catalytic hairpin assembly with the Au aggregation amplification effect, a lateral flow assay (LFA) is designed for simultaneous detection of liver cancer-associated miRNA and exosomes. The LFA can differentiate between liver cancer patients and healthy individuals with simple operation and high accuracy.

DNA-Programmed Stem Cell Niches via Orthogonal Extracellular Vesicle-Cell Communications

Extracellular vesicles (EVs) are natural carriers for intercellular transfer of bioactive molecules, which are harnessed for wide biomedical applications. However, a facile yet general approach to engineering interspecies EV-cell communications is still lacking. Here, the use of DNA to encode the heterogeneous interfaces of EVs and cells in a manner free of covalent or genetic modifications is reported, which enables orthogonal EV-cell interkingdom interactions in complex environments. Cholesterol-modified DNA strands and tetrahedral DNA frameworks are employed with complementary sequences to serve as artificial ligands and receptors docking on EVs and living cells, respectively, which can mediate specific yet efficient cellular internalization of EVs via Watson-Crick base pairing. It is shown that based on this system, human cells can adopt EVs derived from the mouse, watermelon, and Escherichia coli. By implementing several EV-cell circuits, it shows that this DNA-programmed system allows orthogonal EV-cell communications in complex environments. This study further demonstrates efficient delivery of EVs with bioactive contents derived from feeder cells toward monkey female germline stem cells (FGSCs), which enables self-renewal and stemness maintenance of the FGSCs without feeder cells. This system may provide a universal platform to customize intercellular exchanges of materials and signals across species and kingdoms.

Extracellular vesicles in renal cell carcinoma: challenges and opportunities coexist

Renal cell carcinoma (RCC) represents an extremely challenging disease in terms of both diagnosis and treatment. It poses a significant threat to human health, with incidence rates increasing at a yearly rate of roughly 2%. Extracellular vesicles (EVs) are lipid-based bilayer structures of membranes that are essential for intercellular interaction and have been linked to the advancement of RCC. This review provides an overview of recent studies on the role of EVs in RCC progression, including involvement in the interaction of tumor cells with M2 macrophages, mediating the generation of immune tolerance, and assuming the role of communication messengers in the tumor microenvironment leading to disease progression. Finally, the " troika " of EVs in RCC therapy is presented, including engineered sEVs' or EVs tumor vaccines, mesenchymal stem cell EVs therapy, and reduction of tumor-derived EVs secretion. In this context, we highlight the limitations and challenges of EV-based research and the prospects for future developments in this field. Overall, this review provides a comprehensive summary of the role of EVs in RCC and their potential as a viable pathway for the future treatment of this complex disease.

Magnetic-nanowaxberry-based microfluidic ExoSIC for affinity and continuous separation of circulating exosomes towards cancer diagnosis

Exosomes are seen as promising biomarkers for minimally invasive liquid biopsies and disease surveillance. However, the complexity of body fluids, inherent heterogeneity, and tiny size of exosomes impede their extraction, consequently restricting their clinical application. In this study, in order to efficiently isolate exosomes from clinical samples, an irregular serpentine channel microfluidic chip (ExoSIC) was designed to continuously separate exosomes from plasma based on a magnetic-nanowaxberry (MNWB). In the ExoSIC, irregular serpentine microchannels are utilized to increase fluid chaotic mixing, hence improving exosome capture efficiency. In comparison to commonly used spherical magnetic particles, the designed MNWB can not only enhance the capture efficiency of exosomes, but also possess a size-exclusion effect to improve exosome purity. Consequently, the ExoSIC exhibited a large yield (24 times higher than differential centrifugation), optimum purity (greater than precipitation and similar to differential centrifugation), and high specificity. Furthermore, the ExoSIC was utilized for plasma-based cancer diagnosis by multiplex monitoring of five exosomal biomarkers (exosomal concentration, EGFR, EpCAM, SAA1 and FV), and the AUC reached 0.791. This work provides a comprehensive framework for exosome-based cancer diagnostics in order to meet clinical requirements for exosome isolation and downstream analysis.

A biodegradable and cofactor self-sufficient aptazyme nanoprobe for amplified imaging of low-abundance protein in living cells

Despite the progress on the analysis of proteins either in vitro or in vivo, detection and imaging of low-abundance proteins in living cells still remains challenging. Herein, a novel biodegradable and cofactor self-sufficient DNAzyme nanoprobe has been deve-loped for catalytic imaging of protein in living cells with signal amplification capacity. This DNAzyme nanoprobe is constructed by assembling a DNAzyme subunit-containing aptamer hairpin (HP), another DNAzyme subunit strand (DS), and the molecular beacon (MB) substrate strand onto pH-sensitive ZnO@polydopamine nanorods (ZnO@PDA NRs) that work as DNAzyme cofactor suppliers. Such a nanoprobe can facilitate cellular uptake of DNA molecules and protection of them from nuclease degradation as well as release of them in cells by lysosomal acid-triggered dissolution of ZnO@PDA NRs into Zn²⁺ as DNAzyme cofactor. Upon recognition and binding with the intracellular protein target, the stem of HP is opened, after which the opened HP hybridizes with DS and generates activated DNAzymes. Each activated DNAzyme can catalyze the cleavage of many MB substrates through true enzymatic multiple turnovers, resulting in the separation of the quenched fluorophore/quencher pair labeled in MB and the generation of significantly amplified fluorescence. Using nucleolin (NCL) as a model protein, this nanoprobe enables the analysis of NCL with a detection limit of 1.8 pM, which are at least two orders of magnitude lower than that of non-catalytic imaging probe. Moreover, it could accurately distinguish tumor cells and normal cells by live cell NCL imaging. And the experimental results are also further verified by flow cytometry assays. The developed nanoprobe can be easily extended to detect other biomolecules by the change of their corresponding aptamer sequences, thus providing a promising tool for highly sensitive imaging of low-abundance biomolecules in living cells.