Gene Delivery by Subconjunctival Injection of Adenovirus in Rats: A Study of Local Distribution, Transgene Duration and Safety

Abstract

Subconjunctival injection is a minimally invasive route for gene delivery to ocular tissues, but has traditionally been limited to use in the cornea. The accurate ocular distribution of virus has not, however, been previously investigated. Adenovirus is an attractive gene vector as it can deliver large genes and allow for short-term gene expression, but how safe it is when delivered via subconjunctival injection remains to be established. We have characterized the bio-distribution and safety of subconjunctivally administered adenovirus in Brown Norway rats. The bio-distribution and transgene duration of adenovirus carrying luciferase gene (Ad-Luci) at various time intervals were evaluated via bioluminescence imaging after subconjunctival injection. Adenovirus carrying a reporter gene, β-galactosidase (Ad-LacZ) or hrGFP (Ad-hrGFP) was administered subconjunctivally and the viral distribution in various ocular tissues was assessed by histological analysis and quantitative PCR (qPCR). Hepatic damage was assessed by biochemical and immunohistological analysis with TUNEL stain. Systemic immunogenicity was assessed by measuring serum level of TNF-α via ELISA, 2 hours and 14 days after administration of adenovirus. Retinal function was examined by electroretinography. Subconjunctival injection of Ad-Luci induced luciferase expression in the injected eyes within 24 hours, for at least 64 days. Histological analysis showed adenovirus distributed across anterior and posterior ocular tissues. qPCR demonstrated different amounts of adenovirus in different ocular tissues, with the highest amounts closest to the injection site Unlike the intravenous route, subconjunctivally delivered adenovirus did not elicit any detectable hepatic injury or systemic immunogenicity. Retinal function was unaffected by adenovirus irrespective of administration route. In conclusion, an adenoviral vector administered subconjunctivally can infiltrate into different ocular tissues and lead to short-term ocular transgene expression, without causing hepatic injury and immune activation. Therefore, subconjunctivally administered adenovirus may be a promising gene delivery approach for managing anterior and posterior segment eye diseases requiring short-term therapy.

Viral-mediated Ntf3 overexpression disrupts innervation and hearing in nondeafened guinea pig cochleae

“…Ntf3 induced ABR threshold shifts as early as 1 week after the inoculation. Although we did not measure NT3 levels at earlier time points, gene expression with Adv vectors is known to start and peak within 3–5 days 21–23 and the rapid onset of cochlear degradation is in line with the early timing of Adv gene expression.…”

Inhibition of miR-153 ameliorates ischemia/reperfusion-induced cardiomyocytes apoptosis by regulating Nrf2/HO-1 signaling in rats

“…The adenoviral vector is a desirable tool for a rapid, transient, and robust expression of target gene in the desired area or organ [42,43]. Intramyocardial injection of adenovirus resulted in a lower inflammatory response and higher transgene expression compared to systemic tail vein injection [44,45]. Indeed, we found that adenovirus injection led to local and rapid downregulation of I/R-induced miR-153 in the heart area.…”

Prevention of Corneal Neovascularization by Adenovirus Encoding Human Vascular Endothelial Growth Factor Soluble Receptor (s-VEGFR1) in Lacrimal Gland

“…However, there were concerns that the vector tropism and its gene product were not limited to the ocular surface, as observed in rats in a recent study, and that adenovirus might lead to extensive inflammation, once in the conjunctival area, as recently reported by MRI imaging in an individual with adenoviral conjunctivitis, indicating that the LG, as a postmitotic, encapsulated organ, might be a preferential tissue for gene therapy therapeutic purposes. 60,61 In conclusion, the present work reported proof of concept for using gene therapy with Ad-VEGFR1, targeting the LG to prevent the CNV caused by alkali burns. To improve the efficacy of this strategy, we might need to investigate other vectors capable of carrying s-VEGFR1 and alternatives to block other angiogenic signaling pathways in the cornea.…”