Renal artery injection for delivery of biological materials to the glomerulus (Methods in Renal Research Paper)

Effects of Tissue Pressure on Transgene Expression Characteristics via Renal Local Administration Routes from Ureter or Renal Artery in the Rat Kidney

We previously developed a renal pressure-mediated transfection method (renal pressure method) as a kidney-specific in vivo gene delivery system. However, additional information on selecting other injection routes and applicable animals remains unclear. In this study, we selected renal arterial and ureteral injections as local administration routes and evaluated the characteristics of gene delivery such as efficacy, safety, and distribution in pressured kidney of rat. Immediately after the naked pDNA injection, via renal artery or ureter, the left kidney of the rat was pressured using a pressure controlling device. Transfection efficiency of the pressured kidney was about 100-fold higher than that of the injection only group in both administration routes. The optimal pressure intensity in the rat kidney was 1.2 N/cm² for renal arterial injection and 0.9 N/cm² for ureteral injection. We found that transgene expression site differs according to administration route: cortical fibroblasts and renal tubule in renal arterial injection and cortical and medullary tubule and medullary collecting duct in ureteral injection. This is the first report to demonstrate that the renal pressure method can also be effective, after renal arterial and ureteral injections, in rat kidney.

A surgical technique for homogenous renal distribution of substances in rats

Intra-arterial injection of mesenchymal stem cells has been proven to result in a superior nephroprotection compared to intravenous injection. This avoids initial passage through filter organs such as the lung, liver and spleen. The aim of the present study was to investigate whether suprarenal aortic delivery results in a homogenous distribution to both kidneys. Chinese ink was used to evaluate the renal distribution pattern for the comparison of two retrograde intra-aortic injection methods. In the first, the aorta caudal to the renal branches was temporarily clamped and Chinese ink was injected at the level of the renal arteries. In the second, a distal aortic clamp was combined with alternated clamping of the contralateral arteries. Immediately after injection, kidneys were harvested for histological analysis. Amniotic fluid stem cells labeled with LacZ were injected in the aorta by alternated clamping of the renal arteries in order to track the cells in a rat ischemia/reperfusion model. Without renal artery clamping, intra-aortic administration resulted in a delivery of the ink into the right kidney, whereas administration with alternated clamping of the contralateral renal artery, together with distal aortic artery clamping, resulted in a more homogenous distribution of the ink in both kidneys. Moreover, LacZ-positive cells were found in both kidneys after 6 h of injection. In conclusion, the retrograde administration of Chinese ink in two steps is a fast and reproducible technique, which results in a more homogenous distribution of the stain in both kidneys than a single administration combined by only clamping the aorta.