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Abstract: PO1682

Establishing a Podocyte-PEC Cross-Talk Model Using an Open Microfluidic Co-Culture Device

Session Information

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Zeng, Yuting, University of Washington Department of Chemistry, Seattle, Washington, United States
  • Pippin, Jeffrey W., University of Washington Division of Nephrology, Seattle, Washington, United States
  • Shankland, Stuart J., University of Washington Division of Nephrology, Seattle, Washington, United States
  • Theberge, Ashleigh B., University of Washington Department of Chemistry, Seattle, Washington, United States
Background

Although focal segmental glomerulosclerosis (FSGS) is initially caused by podocyte injuries, their neighboring parietal epithelial cells (PECs) also undergo molecular changes that further damage the glomerulus. The cross-talk between podocytes and PECs is poorly understood, in part due to a lack of appropriate experimental models for study. Our goal is to establish an in vitro coculture model to induce podocyte injury and determine the mediators and responses of PECs.

Methods

Mouse podocytes labeled with EGFP and PECs labeled with tdTomato were cocultured in two neighboring chambers of an open microfluidic device that we engineered. The chambers remain separated until more media is added to overflow the half wall in between. To induce injury, podocytes were exposed to increasing concentrations of cytotoxic sheep anti-glomerular antibodies (or media alone as control) for 2 hours. The two chambers were then allowed to communicate passively for 1 to 4 days. Diffusion calculations suggested moderate sized (10 kDa) signaling molecules take approximately 2 days to reach the other chamber. Immunocytochemistry characterized podocyte injury and PEC activation and epithelial-mesenchymal transition (EMT).

Results

By day 1, the normal contiguous monolayer of podocytes was disrupted, accompanied by a dose-dependent increase in the de novo expression of the injury marker desmin. In contrast to F-actin staining of the control group exhibiting thick bundles of cortical actin at cell edges, resembling primary processes, the level of F-actin decreased predominantly along the cell borders in injured podocytes, consistent with the destruction of podocyte cytoskeletal structures. By day 4, the percentage of PECs expressing the EMT marker SM22 increased significantly. SM22+ PECs were larger and exhibited cellular protrusions, implying enhanced migration and invasion characteristics of the mesenchymal state. The protein expression of CD44, a marker for the activated profibrotic migratory PEC phenotype, was also increased. Levels of SSeCKS remained unchanged in PECs. A time course of bulk RNA seq results from both podocytes and PECs are pending.

Conclusion

This novel in-vitro microfluidic model for coculturing mouse podocytes and PECs has the potential to study many pathways involved in podocyte-PEC crosstalk, glomerular disease mechanisms, and drug screening.

Funding

  • NIDDK Support