Tumor exosome-based nanoparticles are efficient drug carriers for chemotherapy

Developing biomimetic nanoparticles without loss of the integrity of proteins remains a major challenge in cancer chemotherapy. Here, we develop a biocompatible tumor-cell-exocytosed exosome-biomimetic porous silicon nanoparticles (PSiNPs) as drug carrier for targeted cancer chemotherapy. Exosome-sheathed doxorubicin-loaded PSiNPs (DOX@E-PSiNPs), generated by exocytosis of the endocytosed DOX-loaded PSiNPs from tumor cells, exhibit enhanced tumor accumulation, extravasation from blood vessels and penetration into deep tumor parenchyma following intravenous administration. In addition, DOX@E-PSiNPs, regardless of their origin, possess significant cellular uptake and cytotoxicity in both bulk cancer cells and cancer stem cells (CSCs). These properties endow DOX@E-PSiNPs with great in vivo enrichment in total tumor cells and side population cells with features of CSCs, resulting in anticancer activity and CSCs reduction in subcutaneous, orthotopic and metastatic tumor models. These results provide a proof-of-concept for the use of exosome-biomimetic nanoparticles exocytosed from tumor cells as a promising drug carrier for efficient cancer chemotherapy.


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Policy information about availability of computer code Data collection Flow cytometry data were collected with CytExpert and CXP Cytometer; Images were collected with imaging softwares, such as Olympus FluoView for confocal, Leica Application suite V3 for Optical images.

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CytExpert (Ver.2.0.0.153) and CXP Cytometer 2.3 were used to analyze flow cytometric data; Nanoscope was used to analyze AFM data; Imaris 7.4.2 was used to reconstruct the 3D images of 3D tumor spheres; Image J V2.0.0 was used to quantify the images; Statistical analysis was performed using GraphPad Prism 6.
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Flow Cytometry
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Methodology
Sample preparation (1) Cultured cells were trypsinized, washed with PBS for three time, then cells were collected for cytometric analysis; (2) For analysis of side population cells in tumor tissues, tumor tissues were collected, washed with PBS and then cut into small pieces, followed by digestion with 1 mg/mL collagenase type I solution at 37 °C for 2 h. The single tumor cells were acquired by filtering the digested cells with 200-mesh nylon twice. The digested tumor cells were stained with 5 μg/mL Hoechst 33342 for 90 min at 37 °C in the presence or absence of 50 μM verapamil, washed twice with PBS and then subjected to flow cytometric analysis.

Cell population abundance No sorting was involved
Gating strategy For determination of side population cells, briefly, single cells were selected using forward and side scatter linearity. Dualwavelength FACS analysis identified a side branch of 'Hoechst-low' cells as the side population cells, which was further verified by co-adding verapamil, showing a reduction in the size of side population cells.
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