Efficient Gene Knockdown in the Liver <em>via</em> Intrasplenic Injection of Adeno-Associated Virus Serotype 8 (AAV8)-Delivered Small Hairpin RNA

The liver is a major organ that performs essential metabolic functions. Developing an efficient and safe method to knock down gene expression in the liver provides an important tool for determining gene function in liver pathophysiology. In this study, we describe a method for intrasplenic injection of adeno-associated virus serotype 8 (AAV8) engineered to express a small hairpin RNA (shRNA) against a target gene of interest, nucleostemin (NS). Intrasplenic injection of AAV8 expressing an NS-targeting shRNA (AAV8-shNS1) achieved the same knockdown efficiency of NS in the liver as did portal vein injection, compared to the injection of AAV8 expressing a scrambled sequence shRNA (AAV8-shScr). Furthermore, injection of the AAV8-shRNA virus triggered minimal inflammatory reactions in the liver parenchyma. Most importantly, this intrasplenic injection protocol was not technically demanding and caused minimal bleeding at the injection site, which is the leading cause of perioperative and postoperative mortality when performing portal vein injection. This study reports an improved and relatively safe method to achieve efficient gene knockdown in the liver.