Differential effect of cyclosporine A and SDZ RAD on neointima formation of carotid allografts in apolipoprotein E-deficient mice

Background. Apolipoprotein E-deficient (apoE-/-) mice spontaneously develop hypercholesterolemia and atherosclerotic lesions. This may be an appropriate background for the development of graft vessel disease. The authors therefore investigated the effects of cyclosporine A (CsA) and SDZ RAD (RAD, everolimus, Certican) on neointima formation of carotid allografts in apoE-/- mice. To ascertain that equipotent immunosuppressive doses were used, the authors also investigated their effects on cardiac allografts using the same wild-type strain combination. Methods. Heterotopic heart allotransplantation was performed in the BALB/c to C57BL/6 strain combination. Graft survival was monitored daily. Orthotopic carotid artery allotransplantation was performed from BALB/c to apoE-/- (C57BL/6) mice. Groups of mice were treated for 8 weeks with placebo; CsA 10, 20, and 30 mg/kg/d; or RAD 0.3, 1.0, and 3.0 mg/kg/d using ALZET minipumps. Body weight, CsA blood levels, serum lipids, and histology were examined 8 weeks after transplantation or on the day of rejection. Results. Compared with the placebo group, CsA or RAD did not affect body weight. Both CsA and RAD prolonged the survival of cardiac grafts in a dose-dependent manner. CsA blood levels were not different between wild-type and apoE-/- recipients. CsA increased total cholesterol and low-density lipoprotein, but not high-density lipoprotein dose-dependently and significantly, but RAD did not affect the lipids. RAD but not CsA significantly attenuated neointima formation. Conclusions. These results suggest that RAD at a dose preventing organ rejection may also prevent transplant vasculopathy even in the presence of hyperlipidemia.