Enhancing effect of ultrasound-mediated microbubble destruction on gene delivery into rat kidney via different administration routes.

Objective: To investigate the efficiency of β-galactosidase gene transfer into rat kidney with ultrasound-mediated microbubble destruction via different injection routes.

Methods: A total of 25 Wistar rats were randomly divided into 5 groups. Four groups received a mixture of optison microbubbles (0.2 mL) and lacz plasmids (25 μg) injection via renal artery, tail vein, anterior tibial muscle and renal parenchyma, respectively. The control group received a mixture of PBS (xx mL) and lacz plasmids (25 μg) via renal artery. Three days after the gene transfer, ultrasound with fixed frequency and power (1 MHz, xxW) was delivered to the kidneys for 3 min. The efficiency of the gene transfer and expression was evaluated on the basis of β-galactosidase expression. The side effects of this method were evaluated by immunohistological method.

Results: β-galactosidase expression could be observed only in tubules but not in glomeruli and interstitial area. The efficiency of renal artery group was higher than that of tail vein, anterior tibial muscle and renal parenchyma group (P<0.05). Immunohistochemical analysis revealed co-expression of β-galactosidase with a roximal tubule marker, megalin, which suggested that ultrasound enhanced gene transfer into the proximal tubular epithelial cells. No β-galactosidase expression was observed in the extrarenal organs. There were no evident pathological and biochemical changes after gene transfer.

Conclusions: Ultrasound-mediated microbubble destruction can transfer gene into kidney via renal artery, tail vein, anterior tibial muscle and renal parenchyma. Compared with renal artery, administrating microbubbles via tail vein and anterior tibial muscle are more convenient and less vulnerarious.