Tacrolimus inhibits intimal hyperplasia in arterialised veins in rats.

OBJECTVES We investigated whether tacrolimus (FK506) can inhibit neointimal formation in arterialised vein grafts in rats. METHODS Lewis iliolumbar veins were implanted into the abdominal aorta of isogeneic rats. Animals in the treatment groups had daily intramuscular injections of tacrolimus at 0.2 mg/kg (group B) and 0.1 mg/kg (Group C), respectively. The control group A had no treatment. Light microscope evaluations of arterialised vein grafts were performed 30 days after operation. We determined the presence of endothelial cells, the thickness of intima and media, and the degree of infiltration by MHC class II positive, CD4 positive, and CD8 positive cells into the adventitia. RESULTS The intimal thickness in group B (5.0±1.0 µm) was statistically lower (P < 0.05) when compared to group C (7.0±3.0 µm). The intimal thickness in untreated group A (12.7±7.0 µm) was statistically higher (P < 0.01) when compared to both treated groups B and C, respectively. The medial thickness and degree of adventitial infiltration by MHC class II positive, CD8 positive, and CD4 positive cells did not differ between groups. CONCLUSION Treatment with tacrolimus (FK506) showed a dose dependant inhibition of neointimal hyperplasia in arterialised vein grafts in rats (Tab. 1, Fig. 3, Ref. 22).