Suppression of heart NF-κB p65 expression by jugular vein injection of RNAi in mice.

The nuclear factor-kappaB (NF-κB) in cardiac vascular endothelial cells (type II VEC) is a key factor that activates delayed xenograft rejection (DXR), and therefore inhibition of NF-κB gene expression may alleviate post-transplant rejection. siRNA technology was used to inhibit NF-κB p65 gene expression in ICR mice. After jugular vein injection of siRNA/in vivo-jetPEI complex, fluorescence levels of FAM-labeled siRNA in hearts and lungs were much higher after jugular vein injection than tail vein injection, suggesting more efficient siRNA delivery to the heart through the jugular vein. The amount of FAM fluorescence of hearts increased to the highest level between 48 and 72 hours after injection, and decreased gradually 1 week after injection. A minimum dose of 6 nmol NF-κB p65 siRNA and a siRNA/in vivo-jetPEI ratio of 6 (N/P = 6) were required for in vivo siRNA-mediated gene silencing in the heart. Under these conditions, application of siRNA/in vivo-jetPEI complexes from the jugular vein successfully suppressed NF-κB p65 expression in the heart. The same strategy can be applied to heart transplant animal models to protect against NF-κB gene-related type II VEC activation and xenograft rejection.