KIDNEY-TARGETED LIPOSOME-MEDIATED GENE-TRANSFER IN MICE

To develop gene therapy targeted to the kidney, we compared three diff erent routes of liposome-mediated gene delivery to the kidney in mice, ie intra-renal-pelvic, intra-renal-arterial, and infra-renal-parenchy mal injections. A plasmid construct, pCMV beta gal, containing a cytom egalovirus (CMV) immediate-early gene promoter and a beta-galactosidas e reporter gene was mixed with a 1:1 liposome mixture of N[1-(2,3-diol eoyloxy)propyl]-N, N, trimethylam, monium chloride (DOTMA)/dioleoyl ph osphatidyl ethanolamine (DOPE). The pCMV beta gal-liposome complex was injected into the left kidney via three different routes. The efficac y of gene transfer was assessed using 5-bromo-4-chloro-3-indolyl beta- D-galactopyranoside (X-gal) staining on frozen kidney sections 3 to 42 days after injections. Cells with beta-galactosidase activity were de tected in the cortex and outer medulla in both intra-renal-pelvic and intra-renal-arterial groups, but not in the intra-renal-parenchymal gr oup or in the contralateral noninjected kidney. Evidence of gene trans fer was observed only in tubular epithelial cells, but not in glomerul ar, vascular, or interstitial compartments. The levels of beta-galacto sidase expression started to decrease 3 weeks after injection. The gen e transfer in the kidney was not associated with nephrotoxicity as ass essed by blood urea nitrogen levels and renal histology. We conclude t hat both intra-renal-pelvic and intra-renal-arterial injections provid e a transient gene transfer to the renal tubular cells and are suitabl e routes for kidney-targeted gene therapy.