The effect of stem cell transplantation on immunosuppression in living donor renal transplantation: a clinical trial.

Background/objective: We designed a clinical trial on a group of live-donor renal transplantation (LDRT) patients subjected to pre-transplant stem cell transplantation (SCT) to minimize immunosuppression to low-dose steroid monotherapy.

Methods: LDRT patients subjected to pretransplant SCT who had stable graft function for ≥2 years and serum creatinine (SCr) <2 mg/dL were recruited. Patients with diabetes, hepatitis C/B, rejections, or unwilling to participate, were excluded. They had been subjected to non-myeloablative conditioning of total lymphoid irradiation (TLI)/bortezomib and cyclophosphamide, rabbit-antithymocyte globulin (r-ATG) and rituximab with SCT. The maintenance immunosuppression consisted of calcineurin inhibitors (CNI) and/or anti-proliferative agents and prednisone. Donor-specific antibodies (DSA) and peripheral T-regulatory cells (CD127(low/-)/4(+)/25(high)) (p-Tregs) were studied before and after withdrawal of major immunosuppressants; graft biopsy was taken after 100 days of withdrawal in willing patients. Rejections were planned to be treated by anti-rejection therapy followed by rescue immunosuppression.

Results: All immunosuppression but prednisone, 5-10 mg/day has been successfully withdrawn for a mean of 2.2 years in 76 patients with a mean age of 31.4 years and a mean donor-recipient HLA match of 2.9. The mean SCr of 1.4 mg/dL and p-Tregs of 3.5% was remained stable after withdrawal; DSA status was negative in 35.5% and positive in 47.4% patients. Protocol biopsies in all 10 patients who gave the consent were unremarkable.

Conclusion: Stable graft function in LDRT on low-dose steroid monotherapy using pre-transplant SCT under non-myeloablative conditioning with generation of p-Tregs can be achieved successfully and safely.