In the treatment group (Tacrolimus + sirolimus) the investigators will use tacrolimus (starting with 0.1 mg/kg twice daily adjusted to target serum levels by 4-8 ng/ml at the third month and then 3-7 ng/ml from the third month to the 12th month) and sirolimus 2 mg/day (adjusted serum levels at 4-8 ng/ml throughout the study period).