Adult kidney stem cells are known to have important roles in renal regeneration after acute kidney injury. Although trophic factors from tissue stem cells have been reported to promote the regeneration of other organs, there is limited number of evidence of this phenomenon in the kidneys. Here, we explored the effects of secreted factors from kidney stem cells. We intraperitoneally administered culture supernatant obtained from adult rat kidney stem/progenitor cells into rat kidney ischemia/reperfusion injury models, and the treatment significantly ameliorated renal tubulointerstitial injury, suppressed tubular cell apoptosis, diminished inflammation and promoted the proliferation of both residual renal cells and immature cells. In vitro, treatment with culture supernatant from kidney stem cells significantly promoted cell proliferation and suppressed cisplatin-induced cell apoptosis in both normal rat kidney cells and kidney stem cells. In addition, treatment with culture supernatant increased the expression of nestin in normal rat kidney cells, suggesting the dedifferentiation of tubular cells into stem-like cells. Analysis of the culture supernatant revealed that it contained a variety of growth factors. Taken together, the results suggest that these factors together lead to renal regeneration. In conclusion, adult kidney stem cells contribute to renal regeneration indirectly through the secretion of regenerative factors.

已知成人肾干细胞在急性肾损伤后在肾再生中具有重要作用。尽管已经报道了来自组织干细胞的营养因子促进其他器官的再生，但是在肾脏中这种现象的证据有限。在这里，我们探讨了肾脏干细胞分泌因子的作用。我们将来自成年大鼠肾干/祖细胞的培养上清液腹膜内给药至大鼠肾缺血/再灌注损伤模型，该治疗显着改善了肾小管间质损伤，抑制了肾小管细胞凋亡，减轻了炎症，并促进了残余肾细胞的增殖和未成熟细胞。体外，用来自肾干细胞的培养上清液处理可明显促进正常大鼠肾细胞和肾干细胞的细胞增殖并抑制顺铂诱导的细胞凋亡。另外，用培养上清液处理可增加正常大鼠肾细胞中巢蛋白的表达，提示肾小管细胞去分化为干细胞样细胞。对培养物上清液的分析表明，它含有多种生长因子。两者合计，结果表明这些因素共同导致肾脏再生。总之，成年肾干细胞通过分泌再生因子间接促进肾脏再生。