Viral derived “nanoblades” loaded with cas9/ sgrna ribonucleoproteins and aav6 for donor dna cassette delivery

Abstract

Programmable nucleases have enabled rapid and accessible genome engineering in cells andliving organisms. However, their delivery into target cells can be challenging, specially intoprimary cells. Here, we have designed Nanoblades, a new technology to deliver a genomiccleaving agent into cells. These are murine leukemia virus-derived virus like particle (VLP),which are loaded with Cas9 protein through fusion with the gag viral structural protein, andwith guide RNAs. Cas9 together with gRNAs introduces site specifics double strand break(DSBs) in target gene which can be repaired by non-homologous end-joining (NHEJ) or byhomology-directed repair (HDR) introducing a new sequence from an exogenous templateDNA bearing homology to the sequences flanking the DSBs (donor-DNA).Previously, we demonstrated that Nanoblades were extremely efficient in delivery of theirCas9/sgRNA cargo into K562 human cell line and human T, B , HSCs and HSCs derivedprogenitors T cells (pro-T cells ), thanks to their surface co-pseudotyping with baboonretroviral and VSV-G envelopes.The objective of this work was to edit Wiscott Aldrich Syndrome (WAS) gene locus by HDRusing Nanoblades and AAV6 carrying a donor-DNA, which consists in GFP reporter geneflanking by homologous arms of the WAS gene.AAV6 were added to K562 cells at different times points with respect to Nanobladesaddition, in order to find optimal time that maximizes HDR. Different multiplicities ofinfection (MOI) of AAV were tested. HDR-mediated gene editing was determined by PCRand GFP expression by FACS, 7 days after Nanoblades addition.Our results shows that HDR-mediated edition of WAS gene occurred in a 50% of cells, whennanoblades and AAV6 (MOI 100000 vg/cell) were added at same time. We are currentlytesting this protocol of AAV6 and Nanoblades in HSCs and pro-T cells.In summary, Nanoblades in combination with AAV6 carrying donor-DNA are efficienttools for gene editing and have important prospects for basic and clinical translation forgene therapy.