Abstract: TH-PO318

CNT/CD-Specific Injury Triggers Serial Proliferation of Aqp2+ Progenitor Cells in Adult Mouse Kidney

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

  • Zhang, Long, Albany Medical College, Albnay, New York, United States
  • Gao, Chao, Albany Medical College, Albnay, New York, United States
  • Chen, Lihe, NIH, Bethesda, Maryland, United States
  • Zhang, Ye, Albany Medical College, Albnay, New York, United States
  • Chen, Enuo, Albany Medical College, Albnay, New York, United States
  • Zhou, Qiaoling, Xiangya Hospital, Changsha, China
  • Zhang, Wenzheng, Albany Medical College, Albnay, New York, United States
Background

The existence of stem/progenitor cells in adult kidneys and their function in kidney injury repair remain very controversial.

Methods

Hence, iDTRf/f Aqp2Cre mice were generated to selectively activate expression of the simian diphtheria toxin (DT) receptor in Aqp2+ progenitor cells, which generate all known cell types of the connecting tubule/collecting duct (CNT/CD). Adult iDTRf/f Aqp2Cre and iDTRf/f mice were injected with DT at 2-10 μg/kg to induce acute injury in CNT/CD.

Results

iDTRf/f Aqp2Cre mice died at a time- and dose-dependent manner, with 80% mice being dead by day 15 post DT injection. However, all iDTRf/f mice survived the time course. To accurately label two sequential cell divisions, thymidine analogs, 5-chloro-2-deoxyuridine (CldU) and 5-iodo-2-deoxyuridine (IdU) were injected, either alone or sequentially. IdU+ CldU+ cells were exclusively detected in mice that received both IdU and CldU, verifying the labeling specificity. iDTRf/f Aqp2Cre vs. iDTRf/f mice significantly increased the number of labeled cells (CIDU+, IdU+, or both) (88.3 vs. 0.4 cells/section, n=5-9 mice). Triple IF combining CIdU and IdU with various markers was performed with kidneys from 10 DT-induced, CIdU and IdU-chased iDTRf/f Aqp2Cre mice. For each marker, one section/mouse was completely examined for labeled cells that were positive for the marker. For Aqp2+ cells, the double-labeled rate (CldU+ IdU+ / (CldU+ + IdU+ + CldU+ IdU+) was significantly higher (74.8%, 595/795) than the expected (19.4% CldU+ × 5.8% IdU+ = 1.1%) if cell division were stochastic. The high double-labeled rate was also seen in labeled V-ATPase B1B2+ (84.3%, 118/140), Pendrin+ (100%, 10/10), NCC+ (87%, 174/200), THP+ (75%, 18/24), Megalin+ (61%, 183/300) and Aqp1+ (73.5%, 189/257) cells. Only 87 of 31071 Aqp2+ cells were labeled (0.28%). Among 595 double labeling cells, Aqp2+ and Aqp2- cells were 25% and 75%, respectively.

Conclusion

The non-stochastic pattern argues against the notion that all surviving CNT/CD cells are capable of proliferating through self-duplication and suggests that adult Aqp2+ progenitor cells selectively proliferate after injury resulting in a high double-labeled rate after sequential CldU and IdU pulses. CNT/CD-targeted injury induces a global effect within the kidney and invokes proliferation of other progenitor cells.

Funding

  • NIDDK Support