Abstract
Abstract: :
Purpose: Retroviral gene therapy vectors are capable of long-term genetic modification of target cells and may be a viable gene therapy approach for diseases of the corneal endothelium. To date, studies of retroviral gene therapy to the corneal endothelium have utilized HIV-based lentiviral vectors, and tranduction efficiencies have been relatively low (<30%). This study was undertaken to evaluate equine infectious anemia virus (EIAV) as a gene therapy vector for the corneal endothelium. Methods: A three-plasmid system and 293-T cells were used to produce EIAV particles encoding the vesicular stomatitis virus envelope protein and enhanced green-fluorescent protein (eGFP) as a marker. EIAV particles at 3.7 x 107 titer were suspended in media and incubated with ex-vivo human corneas at 37oC for 6 or 24 hours. At the conclusion of the viral incubation, corneas were placed into fresh media and incubated at 37oC for an additional 72 hours. Corneas were fixed in 4% formaldehyde and examined by fluorescence microscopy for eGFP expression. Results: Expression of eGFP was detected in 40-50% of target endothelial cells. Minimal expression was detected in epithelial cells and keratocytes at cut edges of the tissue. No toxic effects of the EIAV vector were observed at the particle concentrations used in this study. Conclusions: High efficiency gene transfer to human corneal endothelium is possible with non-human retroviral vectors such as EIAV. Additional studies are needed to optimize transduction efficiencies further and to investigate the duration of target gene expression. EIAV as a gene therapy vector may represent an attractive alternative to HIV-based vectors for the treatment of corneal diseases.
Keywords: gene transfer/gene therapy • cornea: endothelium • cornea: basic science