The Presence of Recipient-Derived Renal Cells in Kidney Allografts

OBJECTIVE: Stem cells may be involved in the repair processes of renal tissues during various disorders. We aimed to search the presence of recipient originated cells in renal allograft tissues from patients with various types of allograft dysfunction including acute rejection, acute tubular necrosis, calcineurin inhibitor toxicity, and chronic rejection. MATERIAL and METHODS: Eleven kidney transplant recipients were enrolled in the study. Seven patients who had sex-mismatched donors were regarded as the study group and the remaining were the controls (male-male, positive controls, n=2; female-female, negative controls, n=2). Histopathological examinations in the study group had revealed chronic rejection in four patients(together with calcineurin inhibitor toxicity in three) and acute rejection, acute tubular necrosis, and cyclosporine toxicity in one patient each. Deparaffi nised biopsy specimens were examined using chromogenic in situ hybridization (CISH) method for the XY cocktail probe. RESULTS: Renal cells of positive controls had XY, whereas those of negative controls had XX chromosomal signals. Examination of the biopsy samples from the study group showed variable ratios of recipient-derived tubular(2-76%), interstitial mesenchymal(5-83%), and endothelial cells(1-53%). CONCLUSION: The presence of recipient-derived renal cells in injured kidney allografts suggests that there is a possible dynamic interaction between allograft and stem cells of the recipient. Further studies are needed to clarify the origin and the function of these cells.