3D printed perfusable renal proximal tubule model with different extracellular matrix compositions

This paper describes the design of a chip modeling the proximal renal tubule, namely the nephron segment that is most targeted by drug toxicants. The tubule model is based on a 3D convoluted geometry whose printing parameters and Pluronic concentration were optimized to achieve a diameter of $320~\mu \text{m}$ without discontinuities. A perfusion system guaranteeing a $1~\mu \text{L}$ /min flow was also integrated. Moreover, the tubule model was integrated into a gel recapitulating the composition and the elastic properties of the human kidney extracellular matrix. Different formulations containing Matrigel, Collagen I and transglutaminase were investigated and compared in terms of rheometric properties and renal cell viability and ability to form a compact layer on them. Optimal results were found with a matrix composed of Matrigel and Collagen I (especially in the ratios 1:1), with the addition of 2.7% transglutaminase and 0.9% CaCl2.