Gold Nanoparticle-Assisted Virus Formation by Means of the Delivery of an Oncolytic Adenovirus Genome.

Luis Sendra,José De La Higuera,María José Herrero,Antonio Miguel,Luis Alfonso Rojas,Ramón Martínez-Máñez,M Dolores Marcos,Consuelo Cháfer-Pericás,Salvador F Aliño,Elena Aznar,M Carmen Navarro-Plaza,Ramón Alemany

doi:10.3390/nano10061183

Abstract

Oncolytic adenoviruses are a therapeutic alternative to treat cancer based on their ability to replicate selectively in tumor cells. However, their use is limited mainly by the neutralizing antibody (Nab) immune response that prevents repeated dosing. An alternative to facilitate the DNA access to the tumor even in the presence of anti-viral Nabs could be gold nanoparticles able to transfer DNA molecules. However, the ability of these nanoparticles to carry large DNA molecules, such as an oncolytic adenovirus genome, has not been studied. In this work, gold nanoparticles were functionalized with different amounts of polyethylenimine to transfer in a safe and efficient manner a large oncolytic virus genome. Their transfer efficacy and final effect of the oncolytic virus in cancer cells are studied. For each synthesized nanoparticle, (a) DNA loading capacity, (b) complex size, (c) DNA protection ability, (d) transfection efficacy and (e) cytotoxic effect were studied. We observed that small gold nanoparticles (70–80 nm in diameter) protected DNA against nucleases and were able to transfect the ICOVIR-15 oncolytic virus genome encoded in pLR1 plasmid. In the present work, efficient transgene RNA expression, luciferase activity and viral cytopathic effect on cancer cells are reported. These results suggest gold nanoparticles to be an efficient and safe vector for oncolytic adenovirus genome transfer.

Highlights

The use of nanoparticles (NPs) for transferring nucleic acids has attracted increasing interest due to their low cytotoxicity, immunogenicity, biocompatibility and the easy functionalization of their surface [1,2,3]
Gold nanoparticles were functionalized with different amounts of polyethylenimine to transfer in a safe and efficient manner a large oncolytic virus genome
We observed that small gold nanoparticles (70–80 nm in diameter) protected DNA against nucleases and were able to transfect the ICOVIR-15 oncolytic virus genome encoded in pLR1 plasmid

Summary

Introduction

The use of nanoparticles (NPs) for transferring nucleic acids has attracted increasing interest due to their low cytotoxicity, immunogenicity, biocompatibility and the easy functionalization of their surface [1,2,3]. Several studies confirm that positively charged NPs exhibit greater affinity for cell membranes than the negatively charged ones, being more efficient at entering the cytoplasm This is an important consideration in applications involving the transfer of biomolecules into the cell nucleus [11]. Employing plasmids that encode oncolytic viruses instead of using viruses themselves could mediate a conditional replication of the virus only in cancer cells but avoid their undesired immune effect [35] This could permit employing these viral genome plasmids upon repeated administration for longer periods without losing their efficacy. A study in mice showed a promising antitumor effect using an oncolytic plasmid encoding the adenovirus death protein [36] In this sense, and aiming at avoiding the use of oncolytic adenovirus itself and its immunogenicity, we have developed PEI-AuNPs that allow carrying large DNA molecules, such as the adenovirus genome. This strategy avoids the neutralization of the therapeutic agent by circumventing the use of an immunogenic viral particle and by coating the DNA with nanoparticles to prevent the nucleases’ action

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