Purpose: Leukocytes play a critical role in ocular diseases such as uveitis, diabetic retinopathy, and choroidal neovascularization. Intercellular adhesion molecule (ICAM)-1 is essential for the migration of leukocytes. Control of ICAM-1 expression may lead to therapies for these diseases. Small-interfering ribonucleic acids (siRNAs) are efficient specific modulators of endogenous gene expression. The authors describe the application of siRNA to suppress ICAM-1 expression on the murine neurosensory retina or retinal pigment epithelial (RPE) cells using a hydrodynamics-based transfection technique (HT) and intravitreal injection (IV) in vivo.
Methods: ICAM-1-specific plasmid siRNAs designed from the murine gene sequence were transfected into the retina using HT and IV in vivo. Green fluorescent protein (GFP) expression plasmid vector is used as a transfection marker in the retinal cells. ICAM-1 expression was analyzed by enzyme-linked immunosorbent assay and flow cytometry. ICAM-1 upregulation was induced by retinal laser photocoagulation and streptozotocin (STZ).
Results: After the administration of GFP expression plasmid with HT and IV, histologic analysis showed GFP fluorescence in every layer of the murine retina. After photocoagulation, ICAM-1 expression in the neurosensory retina or RPE cells transferred with plasmid ICAM-1 siRNA was significantly decreased compared with cells that were not transfected or cells transferred with scrambled control siRNA. Plasmid siRNAs silenced ICAM-1 expression after STZ administration compared with control or naked siRNA injection.
Conclusions: SiRNA expression mediated by this plasmid causes efficient and specific downregulation of ICAM-1 expression, suggesting that it can be silenced by plasmid siRNA in murine retina in vivo. This technology may lead to novel concepts to reduce retinal neovascular disease by inhibiting leukocyte infiltration.