Cationic liposome-mediated gene transfer to rat salivary epithelial cells in vitro and in vivo

Background: Previously we have shown that gene transfer to salivary gland epithelial cells readily occurs via recombinant adenoviruses, although the response is short-lived and results in a potent host immune response. The aim of the present study was to assess the feasibility of using cationic liposomes to mediate gene transfer to rat salivary cells in vitro and in vivo. Methods: Initially, for transfection in vitro, we used two cationic liposome formulations (GAP-DLRIE/DOPE and DOSPA/DOPE) complexed with plasmid encoding human growth hormone (hGH) as a reporter gene. Thereafter, using GAP-DLRIE/DOPE, plasmids were transferred to rat salivary glands in vivo, and hGH levels measured in saliva, serum and gland extracts. Results: Under optimal conditions, transfection of rat submandibular glands (SMGs) was consistently observed. Approximately 95% of the cells transfected with a plasmid encoding β-galactosidase were acinar cells. Maximal hGH expression was obtained during the first 48 h post-transfection using a plasmid encoding the hGH cDNA and complexed with GAP-DLRIE/ DOPE. hGH was detected in gland extracts and saliva, and occasionally in serum. No systemic or local gland pathology was consistently or significantly observed. Conclusions: The levels of the reporter gene product, hGH, obtained after GAP-DLRIE/DOPE-mediated gene transfer are considerably lower (<0.5%) than those achieved with adenoviral vectors (10⁸ PFU). Nonetheless, cationic liposome-mediated gene transfer to salivary glands may be useful for potential therapeutic applications.