Extruded small extracellular vesicles: splinters of circulating tumour cells may promote cancer metastasis?

We speculate ruptured circulating tumour cells (CTC) in capillaries could release a large number of small extracellular vesicle-like vesicles, namely mechanically extruded sEV (sEVme), which can encapsulate chromosomal DNA fragments. These sEVme have similar physicochemical properties compared to small extracellular vesicles spontaneously secreted by living cells (sEVss), and thus sEVme and sEVss cannot be effectively distinguished based on their size or membrane protein markers. Meanwhile, these sEVme derived from CTC inherit oncogenic payloads, deliver cargo through the bloodstream to recipient cells, and thus may promote cancer metastasis. The validation of this speculation could facilitate our understanding of EV biogenesis and cancer pathology. The potential finding will also provide a theoretical foundation for burgeoning liquid biopsy using DNA fragments derived from harvested sEV.

Enrichment of extracellular vesicles with lipid nanoprobe functionalized nanostructured silica.

Nanoscale extracellular vesicles (nEVs) have recently demonstrated potential value in cancer diagnostics and treatment monitoring, but translation has been limited by technical challenges in nEV isolation. Thus, we have developed a one-step nEV isolation platform that utilizes nEV size-matched silica nanostructures and a surface-conjugated lipid nanoprobe with an integrated microfluidic mixer. The reported platform has 28.8% capture efficiency from pancreatic cancer plasma and can sufficiently enrich nEVs for simpler positive identification of point mutations, particularly KRAS, in nEV DNA from the plasma of pancreatic cancer patients.

Size-based separation methods of circulating tumor cells.

Circulating tumor cells (CTCs) originate from the primary tumor mass and enter into the peripheral bloodstream. Compared to other "liquid biopsy" portfolios such as exosome, circulating tumor DNA/RNA (ctDNA/RNA), CTCs have incomparable advantages in analyses of transcriptomics, proteomics, and signal colocalization. Hence, CTCs hold the key to understanding the biology of metastasis and play a vital role in cancer diagnosis, treatment monitoring, and prognosis. Size-based enrichment features are prominent in CTC isolation. It is a label-free, simple and fast method. Enriched CTCs remain unmodified and viable for a wide range of subsequent analyses. In this review, we comprehensively summarize the differences of size and deformability between CTCs and blood cells, which would facilitate the development of technologies of size-based CTC isolation. Then we review representative size-/deformability-based technologies available for CTC isolation and highlight the recent achievements in molecular analysis of isolated CTCs. To wrap up, we discuss the substantial challenges facing the field, and elaborate on prospects.

Rapid magnetic isolation of extracellular vesicles via lipid-based nanoprobes.

Extracellular vesicles (EVs) can mediate intercellular communication by transferring cargo proteins and nucleic acids between cells. The pathophysiological roles and clinical value of EVs are under intense investigation, yet most studies are limited by technical challenges in the isolation of nanoscale EVs (nEVs). Here, we report a lipid nanoprobe that enables spontaneous labelling and magnetic enrichment of nEVs in 15 minutes, with isolation efficiency and cargo composition similar to what can be achieved by the much slower and bulkier method of ultracentrifugation. We also show that the lipid nanoprobes, which allow for downstream analyses of nucleic acids and proteins, enabled the identification of EGFR and KRAS mutations following nEV isolation from blood plasma from non-small-cell lung-cancer patients. The efficiency and versatility of the lipid nanoprobe opens up opportunities in point-of-care cancer diagnostics.