[Direct gene transfer in the rat kidney in vivo]

Gene delivery to the kidney has both experimental and therapeutic potential in hypertension, although the delivery methods, distribution of transgene and subsequent inflammatory response have been poorly characterized. In adult male Sprague-Dawley rats (200 g, n = 26), the left iliac artery was catheterized and a small catheter (Microbore Tygon S-54-HL) was advanced to the origin of the left renal artery. Loops were tied transiently around the aorta and below the renal arterial bifurcation. After flushing the kidney, the renal vein was tied and 500 microL of transfection solution was instilled. After 15 min all the loops were released, the catheter was removed and the left iliac artery ligated. Both replication-defective adenovirus (ADV) constructions used were based on an Ad5 derivative with a partial E3 deletion. Virus ADV-chloramphenicol acetyl transferase (CAT) and ADV-human placental alkaline phosphatase (hpAP), 10(8), 3 x 10(8), 10(9) and 10(10) plaques forming units/mL (pfu/mL), were used respectively to compare the degree of transfection (CAT) and to localize the transgene in the kidney (hpAP), 48 h after transfection. Controls were infused with vehicle. ADV-CAT 10(10) pfu/mL induced a gene expression, respectively, 1.4 (NS), 12 (p < 0.001) and 28 (p < 0.001) fold greater than the 10(9), 3 x 10(8) and 10(8) pfu/mL formulations. HpAP staining was located in the juxta-medullary part of the cortex, predominantly in the interstitium. Genetically-modified cells were identified as endothelial cells, mainly in peritubular capillaries but also in efferent arterioles and hilar arteries. Highly efficient gene transfer achieved with ADV-hpAP 10(10) pfu/mL was associated with focal necrosis of the proximal convoluted tubules. No changes were observed with the other viral concentrations. Gene delivery, mediated by a replication-defective ADV, to one rat kidney via the renal artery, induced a dose-dependent gene expression located in endothelial cells in peritubular capillaries. Toxicity was observed only with the highest viral concentration.