Development of Adenoviral Delivery Systems to Target Hepatic Stellate Cells In Vivo

Abstract

Hepatic stellate cells (HSCs) are known as initiator cells that induce liver fibrosis upon intoxication or other noxes. Deactivation of this ongoing remodeling process of liver parenchyma into fibrotic tissue induced by HSCs is an interesting goal to be achieved by targeted genetic modification of HSCs. The most widely applied approach in gene therapy is the utilization of specifically targeted vectors based on Adenovirus (Ad) serotype 5. To narrow down the otherwise ubiquitous tropism of parental Ad, two modifications are required: a) ablating the native tropism and b) redirecting the vector particles towards a specific entity solely present on the cells of interest. Therefore, we designed a peptide of the nerve growth factor (NGFp) with specific affinity for the p75 neurotrophin receptor (p75NTR) present on HSCs. Coupling of this NGFp to vector particles was done either via chemical conjugation using bifunctional polyethylene glycol (PEG) or, alternatively, by molecular bridging with a fusion protein specific for viral fiber knob and p75NTR. Both Ad vectors transmit the gene for the green fluorescent protein (GFP). GFP expression was monitored in vitro on primary murine HSCs as well as after systemic administration in mice with healthy and fibrotic livers using intravital fluorescence microscopy. Coupling of NGFp to Ad via S11 and/or PEGylation resulted in markedly reduced liver tropism and an enhanced adenoviral-mediated gene transfer to HSCs. Transduction efficiency of both specific Ads was uniformly higher in fibrotic livers, whereas Ad.GFP-S11-NGFp transduce activated HSCs better than Ad.GFP-PEG-NGFp. These experiments contribute to the development of a targeted gene transfer system to specifically deliver antifibrotic compounds into activated HSCs by systemically applied adenoviral vector modified with NGFp.

Novel subventricular zone early progenitor cell-specific adenovirus for in vivo therapy of central nervous system disorders reinforces brain stem cell heterogeneity

“…We already applied this method to target activated hepatic stellate cells (HSC) via a p75NTR-specific peptide using the S11 adapter molecule. Gene transfer by Ad vectors bound to this complex reduced hepatocyte infection and resulted in specific and enhanced HSC targeting in the liver after systemic virus injection (Reetz et al 2013). In the current study, we used this method to construct selective infectious virus particles against NSPCs obtained from the SVZ of adult mouse brains by coupling the SNQ peptide to the fiber single-chain antibody fragment.…”

In vivo reprogramming of hepatic myofibroblasts into hepatocytes attenuates liver fibrosis: back to the future?

“…This is something that some of the Authors involved in the study are trying to finalize, as already show by data published in an accompanying paper in the same issue of Cell Stem Cell in which they used adeno-associated virus 6 (AAV6) vector expressing hepatic transcription factors (24). Another question is relying on the precise origin of in vivo iHep: although the models used in this study and literature data support a predominant origin from HSCs-derived MFs, one can not exclude that some iHep may originate from other cellular sources, including portal fibroblasts, smooth muscle cells around portal vein, bone marrow-derived mesenchymal stem cells or fibroblasts around central vein (18)(19)(20)(21)(22)(23). Along these lines, and because data from this study indicate that iHep are detected only near to the portal vein or near central vein, it would be of interest to know what happens (i.e., in vivo procedures to reprogram MFs into iHep) in a murine model of the human non-alcoolic fatty liver disease (NAFLD, a major CLD worldwide), in which fibrosis starts with a peculiar perisinusoidal/pericellular pattern mainly involving activated HSCs.…”

“…MFs were generated following a protocol for experimental fibrosis based on chronic administration of carbon tetrachloride (CCl 4 ) and, in order to overexpress the four TFs, a procedure requiring the administration of a p75NTRp-tagged recombinant adenoviral vector expressing the 4TFs from a polycistronic transgene cassette. In vivo targeting of MFs was obtained through portal vein administration of Ad.GFP-S11-NGFp, a vector modified to couple adenoviral fiber knobs with a peptide fragment of NGF (NGFp) allowing specific binding to the p75 neurotrophin receptor (p75NTR) expressed on HSCs and MFs (22). Administration of Ad.GFP-S11-NGFp carrying the 4TFs (Ad4TF) led to overexpression of the 4TFs in sorted MFs without any sign of morphological or liver function alteration.…”

No significant impact of Foxf1 siRNA treatment in acute and chronic CCl4liver injury

“…10 To translate the current knowledge of potential target genes and mechanisms into human therapy, the development of specific and effective delivery systems to the liver as well as drug targeting without evoking systemic side effects are urgently needed. For this purpose, different viral 11 and non-viral 10,12 systems coupled with ligands which specifically bind to receptors solely expressed on HSC, like PDGF-Rb, 13 p75 neurotrophin receptor 11 or retinol-binding protein (RBP) receptor 14 are qualified for a HSC-selective gene or drug delivery. 15 In this way, various studies have focused on the inhibition of the activation or proliferation of HSC, 10 promotion of HSC apoptosis 16,17 or inhibition of ECM deposition.…”