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Kidney Week

Abstract: TH-PO048

A Powerful Anti-Angiogenic Activity in Extracellular Vesicles Isolated from Kidney Endothelial Cells

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Chelvanambi, Sarvesh, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Yoder, Mervin C., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Clauss, Matthias, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Basile, David P., Indiana University School of Medicine, Indianapolis, Indiana, United States
Background

Acute kidney injury and chronic kidney disease are associated with capillary rarefaction, which promotes hypoxia and hastens renal fibrosis. The lack of renal vascular repair following injury is not clearly understood. We hypothesized that kidney endothelial cells have intrinsic signaling properties that impair growth and angiogenesis, thereby contributing to poor vascular repair.

Methods

Rat or mouse primary kidney endothelial cells (rKEC or mKEC) were isolated using Dynabeads conjugated to CD45 (negative selection) and CD31 (positive selection) antibodies. Cells were grown in EGM2 (Lonza) on collagen-coated plastic to evaluate growth rates (MTT) or placed on Matrigel to quantify branching capacity.

Results

Previous studies demonstrated that rKEC grew slower than rat pulmonary EC (rPEC). rKEC consistently grew slower (<5% increase in cell number between day 1-4) than EC from brain, spleen or aorta (~60-100%, p<0.01 vs KEC). rKEC could not form branching structures on matrigel, but integrated into networks formed by rPEC when plated at a 1:100 ratio (KEC to PEC). Increasing ratios of rKEC:rPEC lead to a decline in branch formation with no rPEC branches at a ratio of 50:50. Co-culture of rKEC also inhibited branching of rat brain and aortic EC and human cord blood derived endothelial colony forming cells (ECFC), while EC from other tissues did not convey similar inhibitory activity. Increasing rKEC proliferation with hTERT overexpression did not attenuate rKEC’s ability to disrupt branch formation of ECFC.
We hypothesized that KEC secrete an anti-angiogenic factor which may impair cell growth. Conditioned media (CM) isolated from rKEC reduced growth of the highly proliferative human ECFC by ~ 40% (p<0.001). Similarly, CM isolated from primary mouse KEC decreased ECFC growth by ~50% (p<0.001). CM isolated from mouse heart or lung EC did not contain inhibitory activity. Specifically, only the extracellular vesicle (EV) fraction isolated from mKEC inhibited growth (40% decrease, p<0.001), while the EV depleted supernatant had no effect on ECFC proliferation.

Conclusion

Kidney endothelial cells possess an anti-angiogenic activity that is not observed in EC from other tissues. EV secreted from KEC may contain anti-angiogenic cargo that slow EC growth in vitro. Such activity may underlie impaired renal vascular repair following injury.

Funding

  • NIDDK Support