DYNAMIC STUDY OF THE RENAL ULTRASTRUCTURAL CHANGES IN NANOBACTERIA INDUCED RAT KIDNEY STONE MODEL

To illustrate the dynamic ultrastructural changes during the establishment of a Nanobacteria (NB) induced rat stone model. Ninety Wistar male rats were randomly divided into the control group (NC), NB stone group (NBS), and NB tetracycline group (NBT), with 30 rats in each. The pathological changes, crystal deposition and renal function were examined and MicroCT was used to observe the progression of the stone formation. Rats in the NBS group were more active and restless than in the NC and NBT groups. Enlarged kidneys, with crystal deposition and a distorted corticomedullary structure, were seen in the NBS group after the fourth week. Between weeks 1 and 8, the serum creatinine, blood uric acid, urea nitrogen and urinary calcium levels in the NBS group gradually increased and were higher than in the NBT and NC groups (P<0.05). Intratubular calcium crystals were seen in the NBS and NBT groups, but were not observed in NC rats. Crystallisation score, stone analysis, MicroCT detection and lithogenesis rate were higher in the NBS group than in the NC and NBT groups. Crystallisation score and stone analysis reached statistical significance (P<0.05). Granular degeneration of the tubular epithelium in NBS group was observed in the 4th week, with pathological changes and calcium crystals that increased gradually and were significant after the 8th week. The pathological changes in NBT rats were mild compared to the same time period NBS group and not observed in the NC group. Electron microscopy studies showed crystal deposition in both the NBS and NBT groups after the 3rd week, which was more prominent in the NBS group but not observed in the NC group. Thus, this dynamic study illustrates the ultrastructural changes in rat kidneys during stone formation to identify novel strategies in the diagnosis and treatment of stone disease.