Histone deacetylase inhibition enhances adenoviral vector transduction in inner ear tissue

Abstract

Adenovirus vectors (AdVs) are efficient tools for gene therapy in many tissues. Several studies have demonstrated successful transgene transduction with AdVs in the inner ear of rodents (Kawamoto et al., 2003). However, toxicity of AdVs (Morral et al., 2002) or lack of tropism to important cell types such as hair cells (Shou et al., 2003) appears to limit their experimental and potential clinical utility. Histone deacetylase inhibitors (HDIs) are known to enhance AdV-mediated transgene expression in various organs (Dion et al., 1997), but their effects in the inner ear have not been documented. We investigated the ability of one HDI, trichostatin A (TSA), to enhance AdV-mediated transgene expression in inner ear tissue. We cultured neonatal rat macular and cochlear explants, and transduced them with an AdV encoding green fluorescent protein (Ad-GFP) under the control of a constitutive promoter for 24hrs. In the absence of TSA, GFP expression was limited, and very few hair cells were transduced. TSA did not enhance transduction when applied at the onset of Ad-GFP transduction. However, administration of TSA during or just after Ad-GFP application increased GFP expression in supporting cells approximately 4-fold. Moreover, vestibular hair cell transduction was enhanced approximately 6-fold, and that of inner hair cells by more than 17-fold. These results suggest that TSA increases AdV-mediated transgene expression in the inner ear, including the successful transduction of hair cells. HDIs, some of which are currently under clinical trials (Bakke et al., 2002), could be useful tools in overcoming current limitations of gene therapy in the inner ear using Ad-GFP.

Discovery and Characterization of a Peptide That Enhances Endosomal Escape of Delivered Proteins in Vitro and in Vivo

“…For outer hair cells, we have previously shown similar levels of recombination using liposome-mediated delivery of supernegatively-charged GFP-Cre 40 . The aurein 1.2-+36 GFP-Cre delivery system is the only method that showed significant recombination levels in both inner and outer hair cells 39,41 , and does not require any virus or other molecules beyond a single polypeptide. Significantly, aurein 1.2-+36 GFP-Cre also extended delivered recombinase activity to additional cochlear supporting cells.…”

Gene transfer in inner ear cells: a challenging race

“…acid) or seven lysine residues (Ad-F2K), greatly improves inner ear transduction. 36 Searching for improving the yield of cochlear cell transfection with adenoviral vectors, Taura et al 37 recently discovered that histone deacetylase inhibition enhances adenoviral vector transduction in cochlear explants, and particularly in HCs and SCs. The rep open reading frame encodes four proteins for replication, whereas the cap open reading frame encodes three structural proteins that form the capsid.…”

Hearing Preservation Following Repeated Adenovector Delivery

“…Thus, delivery to the cochlea can be achieved by accessing the vestibular perilymph. The relative isolation of the cochlea reduces the risk of systemic effects to the surrounding tissue (M. Duan et al, ; Taura et al, ; S. Ishimoto et al, ; Suzuki et al, ). Many genes regarding cochlear disorders are already identified and cloned in mice and humans (Lustig and Akil, ).…”

“…Thus, delivery to the cochlea can be achieved by accessing the vestibular perilymph. The relative isolation of the cochlea reduces the risk of systemic effects to the surrounding tissue (M. Duan et al, 2004;Taura et al, 2010;S. Ishimoto et al, 2002;Suzuki et al, 2003).…”