Selective intracellular vaporisation of antibody-conjugated phase-change nano-droplets in vitro

Abstract

While chemotherapy is a major mode of cancer therapeutics, its efficacy is limited by systemic toxicities and drug resistance. Recent advances in nanomedicine provide the opportunity to reduce systemic toxicities. However, drug resistance remains a major challenge in cancer treatment research. Here we developed a nanomedicine composed of a phase-change nano-droplet (PCND) and an anti-cancer antibody (9E5), proposing the concept of ultrasound cancer therapy with intracellular vaporisation. PCND is a liquid perfluorocarbon nanoparticle with a liquid–gas phase that is transformable upon exposure to ultrasound. 9E5 is a monoclonal antibody targeting epiregulin (EREG). We found that 9E5-conjugated PCNDs are selectively internalised into targeted cancer cells and kill the cells dynamically by ultrasound-induced intracellular vaporisation. In vitro experiments show that 9E5-conjugated PCND targets 97.8% of high-EREG-expressing cancer cells and kills 57% of those targeted upon exposure to ultrasound. Furthermore, direct observation of the intracellular vaporisation process revealed the significant morphological alterations of cells and the release of intracellular contents.

Selective intracellular delivery of perfluorocarbon nanodroplets for cytotoxicity threshold reduction on ultrasound‐induced vaporization

“…9E5 is an anti‐epiregulin (EREG) antibody that targets cell membrane–expressed ligands of epidermal growth factor receptors . Previously, we have demonstrated that 9E5‐conjugated PCNDs can be selectively introduced into tumor cells via receptor‐mediated endocytosis and that exposure to ultrasound‐induced intracellular vaporization leads to a rapid disruption of cellular structure . In the present study, we compared cytotoxicity due to vaporization inside and outside cells and demonstrated that intracellular delivery of PCNDs reduces ultrasound pressure for vaporization to induce cytotoxicity.…”

“…9E5 hybridoma cells were intraperitoneally implanted in BALB/c nude mice, and ascites were obtained and purified on a Protein G column. 9E5 monoclonal antibody was prepared and biotinylated as described previously . All animals were maintained in accordance with the regulations set by the University of Tokyo, and all animal experiments were conducted following institutional guidelines.…”

“…To selectively introduce PCNDs into the targeted tumor cells, the monoclonal antibody 9E5 was conjugated to PCNDs . 9E5 is an anti‐epiregulin (EREG) antibody that targets cell membrane–expressed ligands of epidermal growth factor receptors .…”

Design strategies for physical-stimuli-responsive programmable nanotherapeutics

“…The conjugated antibody bound to epiregulin receptors, which are overexpressed on human colonic adenocarcinoma cell line DLD1 and caused 97.8 ± 0.5% accumulation of the nanoparticles into the DLD1 cells, which was significantly higher than the 1.4 ± 0.3% accumulation of the nanodroplets without the antibody. Furthermore, upon insonation, intracellular vaporization generated by the perfluorocarbon liquid in the nanodroplets killed 57% of the targeted DLD1 cells [110]. In a different approach, placental mesenchymal stem cells were used as cell-targeting vectors for the ultrasound-responsive nanoparticles into tumor cells.…”

“…(a) aptamer- and (b) antibody-conjugated ultrasound-responsive nanodroplets designed for tumor targeted therapy and their interaction with cancerous cells and subseqent degradation by ultrasound (Figures taken from references [109] and [110], respectively).…”