Gene transfer to human pancreatic endocrine cells using viral vectors

We have studied the factors that influence the efficiency of infection of h uman fetal and adult pancreatic endocrine cells with adenovirus, murine ret rovirus, and lentivirus vectors all expressing the green fluorescent protei n (Ad-GFP, MLV-GFP, and Lenti-GFP, respectively). Adenoviral but not retrov iral vectors efficiently infected intact pancreatic islets and fetal islet- like cell clusters (ICCs) in suspension. When islets and ICCs were plated i n monolayer culture, infection efficiency with all three viral vectors incr eased. Ad-GFP infected 90-95% of the cells, whereas infection with MLV-GFP and Lenti-GFP increased only slightly. Both exposure to hepatocyte growth f actor/scatter factor (HGF/SF) and dispersion of the cells by removal from t he culture dish and replating had substantial positive effects on the effic iency of infection with retroviral vectors. Studies of virus entry and cell replication revealed that cell dispersion and stimulation by HGF/SF may be acting through both mechanisms to increase the efficiency of retrovirus-me diated gene transfer. Although HGF/SF and cell dispersion increased the eff iciency of infection with MLV-GFP, only rare cells with weak staining for i nsulin were infected, whereas similar to 25% of beta-cells were infected wi th Lenti-GFP. We conclude that adenovirus is the most potent vector for ex vivo overexpression of foreign genes in adult endocrine pancreatic cells an d is the best vector for applications where high-level but transient expres sion is, desired. Under the optimal conditions of cell dispersion plus HGF/ SF, infection with MLV and lentiviral vectors is reasonably efficient and s table, but only lentiviral vectors efficiently infect pancreatic beta-cells .