Mechanism of inhibitory effects of C-phycocyanin on over proliferation of vascular smooth muscle cells and luminal stenosis

Aim: To investigate the effects of C-phycocyanin (C-PC) from Spirulina Platensis on over proliferation of vascular smooth muscle cells (VSMCs), intimal hyperplasia and luminal stenosis after vascular injury. Methods: The VSMCs of rat thoracic aorta were cultured and treated with different concentrations of C-phycocyanin. DNA synthesis and proliferation state of VSMCs were determinated with tritiated thymidine (3H-TdR) incorporation, the expression of of cyclin-dependent kinase inhibitors (P21 and P27) was detected with Western blot and image analysis. Rat model with restenosis of thoracic aorta after balloon damage was constructed. The rats received intragastric administration of C-phycocyanin for 14 days, and the thoracic aorta were taken out. HE staining, immunohistochemistry and image analysis computer system were applied to measure the vessel morphology, SM-α-actin, proliferating cell nuclear antigen (PCNA), and protein expression of P21 and P27. Results: Active proliferation of VSMCs and low expression of P21 and P27 were examined after VSMCs were induced by fetal bovine serum (FBS). C-phycocyanin could significantly inhibit VSMCs proliferation and DNA synthesis, and meanwhile up-regulated quantities of P21 and P27 protein. In rats with balloon injury, C-phycocyanin group had an outstandingly smaller noeintima/media area ratio, larger internal or external elastic lamina area and luminal area; and C-phycocyanin promoted the expression of P21 and P27. Conclusions: C-phycocyanin can inhibit the over proliferation of VSMCs and luminal narrowing after aortic balloon injury. The mechanism is probably that C-PC can promote the expression of key regulatory factors P21 and P27.