Kidney Week

Abstract: TH-PO318

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

Session Information

• AKI: Repair and Regeneration
  November 02, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Acute Kidney Injury

• 002 AKI: Repair and Regeneration

Authors

• Zhang, Long, Albany Medical College, Albnay, New York, United States

Long Zhang,

• Gao, Chao, Albany Medical College, Albnay, New York, United States

Chao Gao,

• Chen, Lihe, NIH, Bethesda, Maryland, United States

Lihe Chen,

• Zhang, Ye, Albany Medical College, Albnay, New York, United States

Ye Zhang,

• Chen, Enuo, Albany Medical College, Albnay, New York, United States

Enuo Chen,

• Zhou, Qiaoling, Xiangya Hospital, Changsha, China

Qiaoling Zhou,

• Zhang, Wenzheng, Albany Medical College, Albnay, New York, United States

Wenzheng Zhang,

Background

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

Methods

Hence, iDTR^f/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 iDTR^f/f Aqp2Cre and iDTR^f/f mice were injected with DT at 2-10 μg/kg to induce acute injury in CNT/CD.

Results

iDTR^f/f Aqp2Cre mice died at a time- and dose-dependent manner, with 80% mice being dead by day 15 post DT injection. However, all iDTR^f/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. iDTR^f/f Aqp2Cre vs. iDTR^f/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 iDTR^f/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