Vol. 305, Issue 1, 40-47, April 2003

Delivery of Peptide Drugs to the Brain by Adenovirus-Mediated Heterologous Expression of Human Oligopeptide Transporter at the Blood-Brain Barrier

Hidekazu Toyobuku, Yoshimichi Sai , Toru Kagami, Ikumi Tamai and Akira Tsuji

Department of Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa, Japan (H.T., Y.S., T.K., I.T., A.T.); Department of Molecular Biopharmaceutics, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan (I.T.); and Core Research Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Kawaguchi, Japan (Y.S., I.T., A.T.)

The feasibility of using adenovirus-mediated human oligopeptide transporter (hPEPT1) gene transfer to achieve peptide drug delivery to the brain across the blood-brain barrier was tested by examining the accumulation of model peptides in a rat brain endothelial cell line (RBEC1) and rat brain after transduction with a recombinant adenovirus encoding hPEPT1-enhanced yellow fluorescent protein fusion gene (AdhPEPT1-EYFP). In vitro uptake of [³H]GlySar was determined in RBEC1 transduced with AdhPEPT1-EYFP. In vivo, the accumulation of cefadroxil in rat brain was evaluated after transduction of AdhPEPT1-EYFP. At pH 6.0, the uptake of [³H]GlySar by RBEC1 transduced with AdhPEPT1-EYFP was increased 4-fold compared with that of nontransduced cells. At pH 7.4, uptake of [³H]GlySar in AdhPEPT1-EYFP transduced RBEC1 was 1.5 times higher than that of nontransduced cells. Unlabeled glycylsarcosine (10 mM) reduced the uptake of [³H]GlySar to a level comparable with that of nontransduced cells. At 30 min after intravenous administration of cefadroxil to rats transduced with AdhPEPT1-EYFP at 3.2 × 10⁹ plaque-forming units/rat by an in situ brain perfusion method, the brain-to-plasma concentration ratio (Kp) of cefadroxil was increased about 2 times compared with that of nontransduced or AdGFP (control vector)-transduced rats, although this was not statistically significant. In contrast, Kp of [¹⁴C]inulin, a marker for extracellular fluid space, remained unchanged after adenoviral transduction. In conclusion, our results suggest that adenovirus-mediated heterologous expression of hPEPT1 in vivo could be a useful approach to deliver oligopeptides to the brain.