MicroRNA‐based recombinant AAV vector assembly improves efficiency of suicide gene transfer in a murine model of lymphoma

Recent success in clinical trials with recombinant Adeno‐associated virus (AAV)‐based gene therapy has redirected efforts in optimizing AAV assembly and production, to improve its potency. We reasoned that inclusion of a small RNA during vector assembly, which specifically alters the phosphorylation status of the packaging cells may be beneficial. We thus employed microRNAs (miR‐431, miR‐636) identified by their ability to bind AAV genome and also dysregulate Mitogen‐activated protein kinase (MAPK) signaling during vector production, by a global transcriptome study in producer cells. A modified vector assembly protocol incorporating a plasmid encoding these microRNAs was developed. AAV2 vectors packaged in the presence of microRNA demonstrated an improved gene transfer potency by 3.7‐fold, in vitro. Furthermore, AAV6 serotype vectors encoding an inducible caspase 9 suicide gene, packaged in the presence of miR‐636, showed a significant tumor regression (~2.2‐fold, P < .01) in a syngeneic murine model of T‐cell lymphoma. Taken together, we have demonstrated a simple but effective microRNA‐based approach to improve the assembly and potency of suicide gene therapy with AAV vectors.