Suppression of pseudointimal hyperplasia by a novel prostacyclin analogue: beraprost

The aim of this study was to evaluate the effect of a novel prostaglandin I2 analogue, beraprost (BPT), on the pseudointimal hyperplasia (PIH) of polytetrafluoroethylene (PTFE) prostheses. A total of 12 rabbits were equally divided into three groups. The control group was given a placebo daily, group 1 was given BPT orally 2 mg/kg per day, and group 2 was given BPT orally 4 mg/kg b.i.d. Exactly 1 cm of the inferior vena cava was resected and replaced by a 3-cm PTFE tube graft. All the grafts were patent when harvested 4 weeks after implantation, but the lumens were narrowed to various extents by PIH. PIH, determined by the dry weight of the intraluminal tissue deposit, was significantly (P < 0.01) suppressed in groups 1 and 2 compared with the control group. High-magnification light microscopy with various staining methods revealed the PIH to be composed mainly of smooth muscle cells (SMCs) and collagen fibrils in all three groups. Transmission electron microscopy revealed that the majority of SMCs in groups 1 and 2 were contractile in form, in contrast with the synthetic form seen in the control group. In conclusion, BPT attenuated the PIH of PTFE grafts by inhibiting the phenotype change in the SMCs.