Effectiveness of narrow-band ultraviolet-b phototherapy for prevention of intimal hyperplasia in a rat carotid balloon injury model

Background and Objective: Narrow-band ultraviolet-B light (NBLTVB) (313 nm) is known to have anti-proliferative effects, implying a potential treatment for intimal hyperplasia, but it remains to be ascertained. We assessed the effects of NBLTVB irradiation for prevention of intimal hyperplasia. Study Design/Materials and Methods: The rat carotid arteries were irradiated with NBLTVB after balloon injury (BI), and the degree of intimal hyperplasia was histopathologically assessed. The anti-proliferative effects using cultured human smooth muscle cells were evaluated by flow cytometry and immunoblot analysis. Results: NBUVB (0.3-4.5 J/cm(2)) irradiation immediately after BI reduced the degree of intimal hyperplasia at 14 and 28 days after BI (P < 0.001) without any obvious complications. Neither an increase in the number of medial cells nor upregulation of proliferating cell nuclear antigen was observed in the irradiated arteries. NBLTVB irradiation at 2 or 14 days after BI significantly suppressed further intimal hyperplasia (P < 0.01). NBUVB-irradiated cultured cells showed inhibited proliferation involved with G, and G(2)/M arrests. Increased expression of p53 and inhibition of retinoblastoma protein (pRB) phosphorylation were also seen in the NBLTVB-irradiated cells. Conclusions: These data suggest that NBLTVB irradiation is an effective method for preventing intimal hyperplasia. The anti-proliferative effect is partly due to the cell cycle arrest caused by p53 expression and inhibited pRB phosphorylation.