肾皮质大部分切除与肾缺血再灌注损伤对大鼠肾干、祖细胞的影响及其对肾损伤预后的意义

目的 比较肾皮质大部分切除与肾缺血再灌注损伤对大鼠肾干、祖细胞的影响，探讨肾干、祖细胞在肾脏损伤修复中的意义及急性肾衰竭（AFR）和慢性肾衰竭（CRF）预后不同的可能机制。 方法 肾动脉结扎再灌注和5/6肾皮质切除术（假手术为对照）分别制作SD大鼠ARF和CRF模型，定期监测血肌酐、尿素氮及24 h尿蛋白量。于设定时间采集肾脏标本，HE染色检查病理改变，免疫荧光检测肾鲍曼囊区CD24、CD133及肾小球podocin表达；RT-PCR检测大鼠肾皮质区podocin mRNA表达和肾组织转化生长因子β1（TGF-β1）、Notch2、肝细胞生长因子（HGF）、成骨蛋白7（BMP7）和Pax-2 mRNA表达。分析5/6肾皮质切除术后Pax-2 mRNA表达量与podocin mRNA表达量及肾小球硬化指数（GSI）的相关性。 结果 两种模型大鼠分别出现急、慢性肾衰竭的典型肾脏病理及功能变化。CRF组随时间延长肾小球硬化指数逐渐升高，于术后第14、30、60、90天分别为（2.34±0.28）%、（25.12±5.67）%、（89.42±12.28）%和（171.23±32.28）%。与假手术组比较，ARF组不同时间点大鼠鲍曼囊区CD24+CD133+表达细胞分布无显著变化，而CRF组大鼠鲍曼囊区CD24+CD133+表达细胞逐渐减弱；ARF组肾小球podocin表达有短暂减少后迅速恢复，而CRF组肾小球podocin表达则进行性减少。与假手术组相比，ARF组HGF、BMP7 mRNA表达升高（P ＜ 0.05），而CRF组TGF-β1、Notch2 mRNA表达升高（P ＜ 0.05），Pax-2和podocin mRNA表达均进行性减少（P ＜ 0.05）。后两者呈正相关（r = 0.872），且均与GSI呈负相关（r = -0.906、-0.872，均P ＜ 0.05）。 结论 肾脏缺血再灌注损伤对大鼠肾干、祖细胞无明显损伤，足细胞修复迅速，肾脏结构及功能完全恢复。肾皮质大部分切除引起大鼠肾干、祖细胞所处环境中生长抑制因子水平上调，促生长因子降低，导致肾干、祖细胞逐渐减损，足细胞修复缺陷，肾小球硬化及肾功能进行性衰竭。两种肾损伤对肾脏干、祖细胞的不同影响及由此产生肾脏再生修复功能的差异可能是其预后不同的主要机制。

Different impacts of subtotal nephrectomy and ischemia-reperfusion injury on renal stem cells and progenitor cells of rats and their significance for renal prognosis

Objective To compare the impacts of subtotal nephrectomy and ischemiareperfusion injury on renal stem cells and progenitor cells of rats,and to explore the significance of renal stem cells and progenitor cells for renal repair and the possible mechanisms of prognosis in rats with acute renal failure (ARF) or chronic renal failure (CRF).Methods Rats of CRF or ARF model underwent 5/6 nephrectomy or renal artery ligation and repedusion respectively,and rars in control group underwent sham operation.Scr,BUN and 24 hour urine protein were regularly measured.Kidney specimens were obtained at the set time for HE staining and fluorescence staining.Expressions of CD24,CD133 and podocin were detected by immunofluorescence.RT-PCR was performed to quantify the expression of transforming growth factor β1 (TGF-β1),Notch2,hepatocyte growth factor (HGF),bone morphogenetic protein 7 (BMP7) and Pax-2 mRNA in renal tissue and the expression of podocin mRNA in renal cortex.Correlation among the expressions of Pax-2 mRNA,podocin mRNA and glomemlosclerosis index were analyzed.Results The rats of two models presented typical ARF or CRF in renal pathology and function.Glomerulosclerosis index in CRF group increased gradually with time,which were (2.34±0.28)％,(25.12±5.67)％,(89.42±12.28)％ and (171.23±32.28)％ at day 14,day 30,day 60 and day 90 respectively.Compared with sham group,the CD24+CD133+ cells of the ARF rats showed no significant change in quantity and distribution,while the CRF rats showed gradual reduction of CD24 +CD133+ cells.The expression of podocin in glomerulus decreased temporarily and recovered finally after ischemiareperfusion injury,but decreased gradually after 5/6 nephrectomy.Compared with sham group,expression of TGF-β1,Notch2 mRNA in renal tissue was increased in CRF group,while the expression of HGF,BMP7 mRNA in renal tissue of ARF group were increased.Between the expression of Pax-2 mRNA in renal tissue and the expression of podocin mRNA in renal cortex,there was positive correlation in CRF group,while they both were negatively correlated with glomerulosclerosis index.Conclusions Ischemia-reperfusion injury makes no obvious impairment to renal progenitor cells.Having progressively injured the living environment of renal progenitor cells,subtotal nephrectomy reduces renal progenitor cells,and causes podocytes to repairing incompetently,which may be the main pathogenesis of CRF with poor prognosis.