Donor pre-treatment with tacrolimus reduces transplant vasculopathy

We tested whether transplant arteriosclerosis can be reduced by pre-treatment of the donor with immunosuppressive agents, using a rat allogeneic aorta transplantation model. Donor rats received no pre-treatment, or tacrolimus, methylprednisolone, rapamycin, or mycofenolate mofetil (MMF) 16 and 2h before explantation of the grafts. Eight weeks after transplantation, aorta allografts were harvested. Percent intima area/intima+media area (I/I+M), inflammatory cells and in situ MMP-2 and -9 activity were determined. In pre-transplantation biopsies, MMP-2 and -9 ratio, and mRNA levels for genes of interest were determined. In pre-transplantation biopsies we found no differences in MMP-2/9 ratio, and Bcl-2, Bax, TGF-beta, HO-1, p21, and HIF-1alpha mRNA expression between the groups. Aorta allografts, pre-treated with tacrolimus, showed significantly lower I/I+M ratio compared to untreated controls (p<0.01). Pre-treatment with methylprednisolone, rapamycin or MMF did not significantly reduce I/I+M ratio. In situ MMP-2/MMP-9 activity was significantly reduced in grafts treated with tacrolimus and rapamycin compared to controls (p<0.05). Immunohistochemistry revealed a high number of CD4+ cells and high CD4/CD8 ratio in grafts pre-treated with tacrolimus. Donor pre-treatment with tacrolimus significantly reduces transplant arteriosclerosis and is associated with reduced in situ MMP-2/MMP-9 activity and increased number of CD4+ cells.