In total 15 de novo renal recipients of 2 HLA-DR mismatched living donors, men and women, 18-65 years of age, will be recruited from the renal transplant clinics of the LUMC. Only patients with SCR abd or an increase in IF/TA in the protocol biopsy 4 weeks or 6 months after transplantation will receive MSC infusions. MSCs from patients without SCR in their biopsy will be only used for feasibility and function studies (as described earlier). Subjects will receive two doses of 1 x 10.6 MSCs per kilogram body weight, intravenously, 7 days apart. The investigators will investigate safety of MSC therapy by assessing the rate of (serious) adverse events in the study population using the World Health Organization (WHO) criteria. Feasibility will be obtained by determining the number of expanded MSCs in relation to the amount of BM collected, number of passages required and time to reach study target doses.