4.5. Intra-arterial infusion of vectors in vivo

In the first set of experiments, the adenoviral vectors carrying the β -galactosidase reporter gene were infused into the renal arteries of four rabbits. A midline laparotomy incision was made and the renal artery of the left kidney was prepared. Adenoviral vectors 2.5 ml, 4x10⁹ pfu, were infused into the renal artery over five minutes through a 0.1 mm butterfly needle. The puncture site in the artery was gently compressed for a couple of minutes for hemostasis. The laparotomy incision was closed in two layers with interrupted sutures and the animal was allowed to recover. The animals were sacrified after four days and the treated kidney was taken for a histological analysis of gene transfer.

In the following tests, the adenoviral vectors were injected into the renal arteries of eleven farm pigs via a midline laparotomy incision in the presence or absence of vasodilators (Table 4). In the first experiment, 2.5 ml, 4 x 10⁹ pfu of adenoviral preparation alone was injected through a 0.1 mm butterfly needle into the lower branch of the left renal artery over five minutes. During the infusion, a vascular clamp was placed proximally on the renal artery. Nine of the eleven pigs allocated to renal gene transfer by intra-arterial infusion were operated according to this scheme, with the exception that vasodilative pharmacological agents were infused intra‐arterially into the lower branch of the renal artery shortly before infusion of the virus preparation, in order to diminish the potential vascular resistance in the kidney and possibly to aid transfection. Five vasodilative agents that are commonly in use were applied in different trials, papaverin 10mg, 20mg, 30mg, 60mg (Papaverin^®, Leiras, Finland), alprostadil 5µg (Caverject^®, Pharmacia & Upjohn, Belgium), enalapril 0.5 mg (Renitec^®, Merck Sharp & Dohme, Netherlands), verapamil 2mg (Verpamil^®, Orion, Finland) and lidocain 100mg (Xylocain^®20 mg ml^–1, Astra, Sweden) (Table 4). One animal received 0.9% physiological saline prior to the viral infusion for control. The animals were sacrificed on the fourth postoperative day, and nephrectomy was made on the left. Samples from the left kidney were taken for histological analysis, and expression of the lacZ transgene was examined visually after staining with X‐gal. Because the infusion was made to the lower pole of the kidney, the upper pole was used as a control.

For splenic gene transfer, two pigs were operated via intra-arterial infusion of vectors. Through a midline laparotomy incision, the spleen was exposed and the splenic artery at hilum was prepared. The adenoviral preparation, 1x10¹¹ pfu in 20 ml of physiological 0.9% NaCl, was infused over 10 minutes into the proximally clamped splenic artery. The laparotomy incision was closed in two layers with interrupted sutures, and the animal was allowed to recover. Four days after the operation the animal was sacrificed and the spleen was taken for histological analysis.