R2: Identification of renal potential progenitor/stem cells that participate in the renal regeneration processes of kidney allograft fibrosis

Aim: Many strategies are explored to ameliorate kidney allograft tubular atrophy and interstitial fibrosis (TA/IF), but little progress has been achieved. The latest evidence suggested that CD133+ cell in kidney represent a potential multipotent adult resident stem cell population that may contribute to the renal injury repair. Here we investigate whether the CD133+ cells exist in transplanted renal and exert a growth and self‐repair procedure in TA/IF. Methods: Allografts from rat kidney transplant models were harvested at 4 weeks, 8 weeks and 12 weeks post transplantation. We performed immunohistochemistry to detect the CD133+ cells and immunofluorescence to detect the co‐expression of CD133 or Pax‐2 with Ki‐67. We furthermore analysed the E‐cadherin using serial sections. Results: CD133+ cells were seldom seen in control kidney, but distributed sporadically in the cortex parenchyma along with the deterioration of TA/IF. The number of CD133+ cell increased after 4 weeks and reached the peak at 8 weeks, then decreased at 12 weeks. From 8 weeks, some new tubules expressing E‐cadherin were constructed with CD133+ cells. Almost all the CD133+ cells were Ki‐67‐positive, but not all the Ki‐67+ cells expressed CD133. The rest Ki‐67+ cells almost expressed Pax‐2. Conclusion: Our study reveals that when majority of the tubules are damaged, a self‐repair mechanism is evoked by potential adult stem cells to compensate the renal function. Thus, potential adult resident stem cells offer a new avenue for autologous cell therapies in TA/IF.