Abstract: SA-OR089

Biodistribution and Homing of Human Endothelial Colony Forming Cell-Derived Exosomes in Ischemia-Reperfusion AKI

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

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

Infusion of human cord blood endothelial colony forming cell (ECFC)-derived exosomes prevents ischemia/reperfusion acute kidney injury (AKI) in mice, via the transfer of microRNA-(miR)-486-5p, which is highly enriched within these exosomes. Whether exosomes selectively home to the kidneys, and possible targeting mechanisms, are unclear.

Methods

Exosomes were isolated from ECFC conditioned media by serial centrifugation. Ischemia-reperfusion injury was induced in mice by bilateral renal vascular clamp (30 min), with i.v. infusion of DiR-labeled ECFC exosomes at the time of reperfusion, followed by optical imaging. miR-486-5p levels were measured by qPCR in various tissues. Cy3-labeled-pre miR-486-5p was used to study the transfer of exosomal miR-486-5p from ECFCs to cultured human umbilical vein endothelial cells (HUVECs). The potential role of the chemokine SDF1-α and its receptor CXCR4 in exosome homing was studied in HUVECs using a blocking antibody to SDF1-α.

Results

In mice, i.v. infusion of exosomes at the time of reperfusion increased kidney miR-486-5p levels after 30 min (p<0.01 vs AKI alone, n=3), with no significant change in miR-486-5p levels in liver, spleen, heart or lungs. After 24 hrs, a further significant increase in miR-486-5p levels was observed only within kidneys (p<0.01, n=3). Optical imaging revealed selective homing of exosomes to the kidneys 30 min after reperfusion (p<0.01, n=4). Conditioned media from ECFCs transfected with Cy3-pre-miR-486-5p induced an increase in cytoplasmic fluorescence within HUVECs, which was blocked when ECFCs were first treated with the exosome release inhibitor GW4869 or when HUVECs were incubated with the inhibitor of pinocytosis, ethylisopropyl amiloride (p<0.001, n=3). By immunoblot, ECFC exosomes expressed CXCR4, and incubation of HUVECs with blocking antibody to SDF1-α prevented exosome uptake (n=3).

Conclusion

ECFC exosomes selectively home to the kidneys after infusion in mice with ischemia-reperfusion AKI, associated with early and sustained increases in kidney levels of miR-486-5p. Endothelial cells are targeted by exosomes, possibly via interaction of CXCR4 with SDF1-α, leading to transfer of miR-486-5p. The results suggest that ECFC exosomes may have therapeutic potential in human AKI due to selective kidney targeting.

Funding

  • Private Foundation Support