Abstract:
Extracellular superoxide dismutase (EC-SOD) has been implicated in regulation of vascular function but its underlying molecular
mechanism is largely unknown. These two-step experiments investigate whether hemagglutinating virus of Japan envelope
(HVJ-E) vector-mediated EC-SOD gene delivery might protect against neointima formation, vascular inflammation, and reactive
oxygen species (ROS) generation, and also explore cell growth signaling pathways. The first in-vitro experiment was performed
to assess the transfection efficacy and safety of HVJ-E compared to lipofectamine®. Results revealed that HVJ-E has higher
transfection efficiency and lower cytotoxicity than those of lipofectamine®. Another in-vivo study initially used balloon denudation to rat carotid artery, then delivered EC-SOD cDNA through the vector of HVJ-E. Arterial section with H&E staining from
the animals 14 days after balloon injury showed a significant reduction of intima-to-media area ratio in EC-SOD transfected
arteries when compared with control (empty vector-transfected arteries) (p < 0.05). Arterial tissue with EC-SOD gene delivery
also exhibited lower levels of ROS, as assessed by fluorescent microphotography with dihydroethidium staining. Quantitative
RT-PCR revealed that EC-SOD gene delivery significantly diminished mRNA expression of tumor necrosis factor (TNF)-α and
interleukin (IL)-1β (p < 0.05 in all comparisons). An immunoblotting assay from vascular smooth muscle cell (VSMC) cultures
showed that the EC-SOD transfected group attenuated the activation of MEK1/2, ERK1/2, and Akt signaling significantly. In
conclusion, EC-SOD overexpression by HVJ-E vector inhibits neointima hyperplasia, inflammation, and ROS level triggered by
balloon injury. The modulation of cell growth-signaling pathways by EC-SOD in VSMCs might play an important role in these
inhibitory effects.
