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Kidney Week

Abstract: SA-PO573

Hypoxia Induces Ligand-Receptor Interactions to Mediate Exosome Targeting to Endothelial Cells in AKI

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Vinas, Jose L., Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Spence, Matthew, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Gutsol, Alex, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Burger, Dylan, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Zimpelmann, Joe A., Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Allan, David, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
  • Burns, Kevin D., Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
Background

Intravenous (i.v.) injection of exosomes derived from human endothelial colony forming cells (ECFCs) leads to selective targeting of the kidneys after ischemic injury in mice, along with increased miR-486-5p levels. Mechanisms mediating recruitment of exosomes are unclear. We previously showed that exosomes express CXC chemokine receptor type 4 (CXCR4), and a neutralizing antibody to stromal cell-derived factor (SDF)-1α prevented exosome uptake into normoxic endothelial cells. Here, we determined if exosomes transfer miR-486-5p to endothelial cells and nephron segments after kidney ischemic injury, and further explored the role of the CXCR4/SDF-1α interaction.

Methods

Ischemia-reperfusion kidney injury was induced in mice by renal vascular clamp, with or without i.v. infusion of ECFC exosomes. Kidneys were removed 30 min after reperfusion, and endothelial cells were isolated by enzymatic digestion and sorting using CD31-labeled magnetic beads, followed by PCR for miR-486-5p. Proximal tubules and glomeruli were microdissected. Human umbilical vein endothelial cells (HUVECs) were exposed to hypoxia to study the role of CXCR4/SDF-1α interaction.

Results

Infusion of ECFC exosomes increased kidney cortical levels of miR-486-5p at 30 min after reperfusion (P<0.05; n=4). Exosomes significantly increased miR-486-5p levels in endothelial cells, proximal tubules, and glomeruli (P<0.05 vs ischemia-reperfusion alone; n=4). PKH26-labeled exosomes were detected mainly in the tubulointerstitial compartment of the kidney 30 min after infusion. In HUVECs, hypoxia increased secreted levels of SDF-1α and enhanced exosome uptake. Incubation with neutralizing antibody to SDF-1α or the CXCR4 inhibitor Plerixafor blocked exosome uptake into hypoxic HUVECs (n=4). Hypoxia also increased uptake of exosomal-derived Cy3-labeled miR-486-5p, which was inhibited by either neutralizing antibody to SDF-1α or Plerixafor (n=4).

Conclusion

ECFC exosomes target endothelial cells, proximal tubules, and glomeruli in ischemic kidneys, with transfer of miR-486-5p. Selective targeting of ischemic kidneys by exosomes may involve an interaction of exosomal CXCR4 with hypoxia-induced SDF-1α in endothelial cells. These data provide further support for the promising therapeutic potential of ECFC exosomes in human acute kidney injury.

Funding

  • Government Support - Non-U.S.