Abstract 1315: RNA Interference for Discoidin Domain Receptor 2 Attenuates Neointimal Formation in Balloon Injured Rat Carotid Artery
Objectives: We sought to test whether inhibition of DDR2 by small interfering RNA (siRNA) can reduce neointimal formation after arterial injury.
Background: Discoidin domain receptor 2 (DDR2) plays potential roles in the regulation of collagen turnover mediated by smooth muscle cells (SMCs) in atherosclerosis. SMCs are activated after arterial injury and contribute to neointimal formation. Little is known about the function of DDR2 in vascular system.
Methods: SMCs from thoracic aorta of adult Wistar rats were cultured. The carotid artery from adult Wistar rats was injured by balloon catheter. DDR2 siRNAs were synthesized by in vitro transcription. DDR2 siRNA was injected to the injured segment by electric pulses. Western blot, real time polymerase chain reaction and immunohistochemical stain were used to detect DDR2 expression.
Results: DDR2 increased the migration activity of SMCs in a dose-dependent manner. DDR2 siRNA inhibited 86% of DDR2 protein expression in cultured SMCs. Delivery of DDR2 siRNA into injured carotid artery reduced DDR2 protein expression in a dose-dependent manner. The most potent dose of DDR2 siRNA to reduce DDR2 protein expression was 10 μM. DDR2 protein and mRNA expression significantly increased at 14 days after carotid injury as compared to sham group. DDR2 siRNA significantly reduced the DDR2 protein and mRNA expression induced by balloon injury. The immunohistochemical stain demonstrated that DDR2 siRNA decreased MMP2 protein labeling induced after balloon injury, a pattern similar to that of DDR2 protein labeling. Thickness of intimal area was significantly increased 14 days after carotid injury. DDR2 siRNA significantly reduced the thickness of intimal area. The thickness of intimal area was reduced by 50% by DDR2 siRNA. DDR2 siRNA did not affect the serum level of interferon-γ.
Conclusions: DDR2 increases migration of SMCs and the expression of DDR2 in the carotid artery significantly increases after injury. RNA interference for DDR2 attenuates neointimal formation after carotid injury. DDR2 plays a pivotal role in the pathogenesis of intimal thickening after mechanical injury.