Cell-Specific Delivery of Diverse Cargos by Bacteriophage MS2 Virus-like Particles

TLDR

Bacteriophage MS2 virus‑like particles possess properties that make them attractive vehicles for targeted delivery of therapeutic and imaging agents. This study reports using MS2 VLPs to selectively deliver nanoparticles, chemotherapeutic drugs, siRNA cocktails, and protein toxins to human hepatocellular carcinoma cells. MS2 VLPs are produced in large quantities, their capsids are genetically or chemically modified to display targeting ligands such as the SP94 peptide, and they self‑assemble with nucleic acids to encapsidate diverse cargos, enabling multivalent targeting and efficient cytosolic delivery. SP94‑decorated VLPs bind HCC cells with 104‑fold higher avidity than non‑target cells, deliver high concentrations of encapsidated drugs or siRNA at sub‑nanomolar or sub‑picomolar doses, and when loaded with ricin toxin A‑chain and a fusogenic peptide, kill virtually all Hep3B cells at 100 fM without harming control cells, demonstrating selective cytotoxicity and superior delivery performance.

Abstract

Virus-like particles (VLPs) of bacteriophage MS2 possess numerous features that make them well-suited for use in targeted delivery of therapeutic and imaging agents. MS2 VLPs can be rapidly produced in large quantities using in vivo or in vitro synthesis techniques. Their capsids can be modified in precise locations via genetic insertion or chemical conjugation, facilitating the multivalent display of targeting ligands. MS2 VLPs also self-assemble in the presence of nucleic acids to specifically encapsidate siRNA and RNA-modified cargos. Here we report the use of MS2 VLPs to selectively deliver nanoparticles, chemotherapeutic drugs, siRNA cocktails, and protein toxins to human hepatocellular carcinoma (HCC). MS2 VLPs modified with a peptide (SP94) that binds HCC exhibit a 104-fold higher avidity for HCC than for hepatocytes, endothelial cells, monocytes, or lymphocytes and can deliver high concentrations of encapsidated cargo to the cytosol of HCC cells. SP94-targeted VLPs loaded with doxorubicin, cisplatin, and 5-fluorouracil selectively kill the HCC cell line, Hep3B, at drug concentrations <1 nM, while SP94-targeted VLPs that encapsidate a siRNA cocktail, which silences expression of cyclin family members, induce growth arrest and apoptosis of Hep3B at siRNA concentrations <150 pM. Impressively, MS2 VLPs, when loaded with ricin toxin A-chain (RTA) and modified to codisplay the SP94 targeting peptide and a histidine-rich fusogenic peptide (H5WYG) that promotes endosomal escape, kill virtually the entire population of Hep3B cells at an RTA concentration of 100 fM without affecting the viability of control cells. Our results demonstrate that MS2 VLPs, because of their tolerance of multivalent peptide display and their ability to specifically encapsidate a variety of chemically disparate cargos, induce selective cytotoxicity of cancer in vitro and represent a significant improvement in the characteristics of VLP-based delivery systems.