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Abstract: SA-PO021

The CAM Model for Ex Vivo Modeling of Vascularized Kidney Tubuloid Epithelium

Session Information

  • Bioengineering
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Bioengineering

  • 300 Bioengineering

Authors

  • Dorileo Leite Bernardi, Murillo, Universitair Medisch Centrum Utrecht, Utrecht, Utrecht, Netherlands
  • Rookmaaker, Maarten B., Universitair Medisch Centrum Utrecht, Utrecht, Utrecht, Netherlands
  • Verhaar, Marianne C., Universitair Medisch Centrum Utrecht, Utrecht, Utrecht, Netherlands
Background

Kidney tubuloids are 3D organoids composed of tubular epithelial cells. Tubuloids can be easily derived from tissue samples as well as urine and have an extensive proliferating capacity. After differentiation, tubuloid epithelium shows active and polarized transport in vitro. The next step toward clinical application is connecting epithelialized membranes to a vascular system. We here present a system for modeling the interaction between tubuloid epithelium and a circulating microvasculature, using the Chick Chorioallantoic Assay (CAM).

Methods

Fertilized Leghorn chicken eggs were cultured ex ovo for 10 days before cell culture inserts were implanted on the CAM. To assess and model the basolateral exposure of tubuloid epithelium in the insert to circulating compounds, the diffusion rate of endogenous urea, and and 70kD dextran-FITC (1mg/ml) from the CAM circulation over bare membranes was quantified with and without angiogenic factors (VEGF and Thrombin). Next, the viability of tubuloid epithelium cultured on the insert membranes on top of the CAM was evaluated. Finally, MRP2/4 dependent transport of CDFDA from the CAM circulation over the membrane as well as through the tubuloid epithelial cells was assessed.

Results

The vascularized bare membranes enabled diffusion from circulating compounds as was demonstrated by the time-dependent increase in the concentration of 10 and 70kD dextran-FITC in the insert after injection in the CAM circulation, with more than 10 fold higher diffusion of 10 than 70kD (2.94 ± 1.12, 0.17 ± 0.15 RFU respectively). We can also modulate the vascular permeability of the CAM with an angiogenic cocktail, which increases the diffusion of 10kD dextran in 2.5 fold (4.02 ± 0.37 against 1.65 ± 0.96 RFU in the control). Kidney tubuloids on inserts maintain their viability and monolayer integrity after the incubation in the embryo. Finally, we showed tubuloid function in the model by the selective secretion of CDFDA from the circulation to the apical compartment.

Conclusion

The CAM assay is a useful system to model crucial aspects of implantable membranes: epithelial integrity and maintenance, membrane vascularization, supply of circulating compounds over the membrane, and epithelial transport function. The presented CAM model enables rapid optimization of vascularized and epithelialized membranes for clinical application.

Funding

  • Government Support – Non-U.S.