Topical gene delivery to normal oral epithelium using adenovirus in organ culture model

Kim, Tae Hwan; Kwak, Myung Ho; Lee, Choon Ho; Park, Jun Woo; Park, Young Wook; Kim, Seong Gon

Abstract

BACKGROUND: Though it is clear that many types of viruses can infect the oral mucosa, its condition for infection is unclear. The purpose of this study was to analyze the conditions for viral infection of normal oral mucosa and explore the possibility of topical gene therapy to oral mucosa using a viral vector.
METHODS
Freshly taken fragments of the palate and the tongue of mice were used for organ culture. The specimens were exposed to green fluorescent protein (GFP)-adenoviral vector for 1 hour except for the control. Initial viral titer was 6.3x1011 pfu/ml and the virus was diluted to working concentrations. The dilution ratio was 1:1,000 (6.3x108 pfu/ml), 1:10,000 (6.3x107 pfu/ml), and 1:100,000 (6.3x106 pfu/ml). They were then cultured on a stainless steel wire mesh in an organ culture dish. The specimens were stereoscopically examined every 24 hours for 6 days, after which they were fixed and analyzed through immunohistochemical methods.
RESULTS
There was no visible expression in the control, 6.3x106 pfu/ml, and 6.3x107 pfu/ml groups. Initial expression was observed at 24 hours after infection in both the palate and the tongue in 6.3x108 pfu/ml and the expression significantly increased until 3 days in the palate and 2 days in the tongue after infection (P<0.05). In both groups, the expression was mostly observed at the resection margin. Immunohistochemical studies showed that the epithelial cells were positive to GFP.
CONCLUSION
The present study showed that topically applied adenovirus containing specific genetic information of GFP could successfully transduce GFP in normal oral epithelial cells at the resection margin in organ culture in terms of dose and exposure time.