Alkaloid rich fraction from Nelumbo nucifera targets VSMC proliferation and migration to suppress restenosis in balloon-injured rat carotid artery

Aims: Restenosis- an adverse consequence following angioplasty, and atherosclerosis are characterized by abnormal vascular smooth muscle cell (VSMC) proliferation and migration leading to neo-intima formation. In the present study, we investigated the inhibitory effects of alkaloid rich fraction (ARF) from Nelumbo nucifera and isolated compound neferine on platelet-derived growth factor (PDGF-BB) induced VSMC proliferation and migration in vitro and neo-intima formation in a rat carotid artery injury model. Methods: PDGF-BB induced VSMC proliferation and migration was assessed using colorimetric assay and modified Boyden chamber method respectively. Gene expression of cell cycle associated molecules was determined by reverse transcription-polymerase chain reaction (RT-PCR). The signaling molecules such as PDGF-Rβ, extracellular regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK), P38, metalloproteinase (MMP)-9 and nuclear factor-kappa B (NF-κB) were determined by western blot analysis. Stress fiber formation was evaluated using immunofluorescence microscopy. The rat carotid artery balloon injury model was performed to assess the effect of ARF on neo-intima formation. Results: ARF possessed the strongest anti-oxidant activities. The anti-proliferative activity of both ARF and neferine was due to suppression of cyclin D1, cyclin E and cyclin-dependent kinase (Cdk) gene expression. Moreover, ARF and neferine inhibited PDGF-Rβ, ERK1/2, JNK and P38 activations and NF-κB translocation. Also, ARF and neferine inhibited VSMC migration by inhibiting MMP-9 activity without affecting cytoskeleton remodeling. In a rat carotid artery injury model, ARF inhibited neo-intima formation. Conclusion: Our results indicate that ARF targets VSMC proliferation and migration to attenuate neo-intima formation by inhibition of PDGF-Rβ mediated signaling.