Polymer-Coated Extracellular Vesicles for Selective Codelivery of Chemotherapeutics and siRNA to Cancer Cells

Combination therapies involving small-interfering RNA (siRNA)-mediated gene silencing and small-molecule drugs are of high interest for cancer treatment. Among the current gene delivery carriers, cell-derived extracellular vesicles (EVs) are particularly promising candidates due to their high biocompatibility, low immunogenicity, in vivo stability, and inherent targeting ability. Here, we developed a multifunctional EV platform capable of selective codelivery of siRNA and doxorubicin (DOX) to cancer cells. siRNA was first loaded into engineered lipid-hybridized EVs (eEVs) to serve as a core. Subsequently, DOX was incorporated into a polyelectrolyte shell surrounding eEVs, which was deposited by layer-by-layer (LbL) assembly. This approach resulted in the production of a stable EV-polymer complex (LbL-eEV) with a diameter of 140.2 ± 9.0 nm and zeta potential of +22.1 ± 0.5 mV. Experiments were performed to assess cellular uptake, cytotoxicity, and gene silencing efficacy in lung adenocarcinoma cells (A549), with noncancerous fibroblast cells (CCL-210) used as a control. The results demonstrated that the LbL-eEV complex can traffic through cells and release siRNA in the cytoplasm, while delivered DOX enters nuclei to induce programmed cell death. Moreover, the inherent selectivity of the particles for cancer cells resulted in effective gene silencing and cancer killing efficiency with reduced cytotoxicity to normal cells. Synchronous delivery of siRNA and DOX was also verified by flow cytometry analysis of single cells. In summary, these data provide a proof of concept for engineering EVs to deliver multiple therapeutics and suggest that LbL-eEVs are a promising drug delivery platform for targeting cancer.