Chemoenzymatic Labeling of Extracellular Vesicles for Visualizing Their Cellular Internalization in Real Time

Anal Chem. 2020 Jan 21;92(2):2103-2111. doi: 10.1021/acs.analchem.9b04608. Epub 2020 Jan 8.

Abstract

Extracellular vesicles (EVs) are intercellular communicators that are heavily implicated in diverse pathological processes. However, it is poorly understood how EVs interact with recipient cells due to the lack of appropriate tracking techniques. Here, we report a robust chemoenzymatic labeling technique for visualizing the internalization process of EVs into target cells in real time. This method uses phospholipase D (PLD) to catalyze the in situ exchange of choline by alkyne in the native EV phosphatidylcholine. Subsequent alkyne-azide click chemistry allows conjugation of Cy5 dyes for visualizing EVs internalization by confocal fluorescence microscopy. The fluorescent labeling of EVs was accomplished in an efficient and biocompatible way, without affecting both the morphology and biological activity of EVs. We applied this chemoenzymatic labeling strategy to monitor the cellular uptake of cancer cell-derived EVs in real time and to further reveal multiple internalization mechanisms. This robust, biocompatible labeling strategy provides an essential tool for EV-related studies ranging from chemical biology to drug delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biocatalysis
  • Cells, Cultured
  • Click Chemistry
  • Extracellular Vesicles / chemistry
  • Extracellular Vesicles / metabolism*
  • Humans
  • MCF-7 Cells
  • Mice
  • Molecular Structure
  • Phospholipase D / chemistry
  • Phospholipase D / metabolism*
  • RAW 264.7 Cells
  • Time Factors

Substances

  • Phospholipase D