Abstract: FR-PO083

Utility of a Vascularized Microphysiological 3D Model of Human Kidney Proximal Tubule for Predictive Tenofovir Toxicity Testing

Session Information

  • AKI Clinical: Predictors
    November 03, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Acute Kidney Injury

  • 003 AKI: Clinical and Translational

Authors

  • Patel, Ranita S., Seattle Children's Hospital, Seattle, Washington, United States
  • Himmelfarb, Jonathan, Kidney Research Institute, Seattle, Washington, United States
  • Kelly, Edward J., University of Washington, Seattle, Washington, United States
Background

Tenofovir is a nucleotide reverse transcriptase inhibitor indicated for the treatment of HIV/AIDS and chronic hepatitis B and used worldwide. Despite its widespread use, nephrotoxic side effects of tenofovir remain a concern. Following exposure to tenofovir in animal and human subjects, clinical markers of kidney injury are increased and associated pathophysiological changes in the kidney proximal tubule are observed. Since tenofovir enters proximal tubule cells via organic anion transporters (OAT) localized to the basolateral membrane and because cells in 2-dimensional cultures often fail to polarize, in vitro cellular toxicity studies have been unsuccessful.

Methods

Primary human proximal tubule cells (PTECs) and human umbilical vein endothelial cells (HUVECs) were cultured in dual channel 3-dimensional microphysiological systems (MPS) to simulate a vascularized proximal tubule for evaluation of tenofovir-induced toxicity. Probenecid, an OAT competitive inhibitor, was added to the HUVEC (vascular) channel in select MPS to assess its role in attenuating tenofovir influx and toxicity. Renal injury biomarkers were used to determine the severity of cellular damage: heme oxygenase-1 (HO-1) signal intensity was quantified following immunocytochemistry and kidney injury molecule-1 (KIM-1) effluent concentrations were measured by ELISA.

Results

Exposure of MPS cultured PTECs from three different tissue donors to 10µM tenofovir for 48 hours induced a 0.9-fold, 4-fold, and 7-fold rise in KIM-1 expression. When 2mM probenecid is concurrently added to the MPS vascular channel, only a 0.5-fold and 2-fold rise in KIM-1 expression is observed. Exposure of MPS cultured PTECs to 100µM tenofovir for 5 days resulted in HO-1 signal intensity 1.8 times that of controls.

Conclusion

These results suggest that our dual channel MPS can function as an ideal ex vivo model to investigate transporter-dependent toxicity. Future efforts include directly inhibiting tenofovir toxicity with the OAT-1 inhibitor probenecid in both HUVEC and PTEC channels to affect both basolateral membrane OATs and apical membrane MRP transporters. Additionally, measurement of drug concentration differentials across HUVEC and PTEC channels can confirm active tubular transport since the HUVEC channel acts as a surrogate capillary for tenofovir infusion.

Funding

  • Other NIH Support