Building Next Generation In Vitro Models of the Renal Nephron at Anatomical Scale

Abstract

Current biofabrication techniques for tissue engineering applications remain limited in theirability to produce perfusable structures with physiologically relevant dimensions, complex 3D organization, and anatomical geometry. In this work, we use multiphoton laser ablation of collagen hydrogels as a subtractive biofabrication strategy to create anatomical renal nephron microstructures, with a particular focus on proximal tubule architecture. To accomplish this, kidney imaging datasets were converted into ablation-compatible 3D models and fabricated within collagen microfluidic platforms. The resulting microchannels supported endothelial and epithelial cell culture and enabled reconstruction of anatomical nephron microenvironments in vitro. Furthermore, laser ablation enabled the fabrication of engineered proximal tubule microchannels with both controlled 3D curvature and luminal diameters below 100 µm, which remains difficult to achieve using conventional biofabrication approaches. Lastly, using these engineered tubular microenvironments, we investigated human renal epithelial cell organization within anatomically scaled lumens. Overall this work extends multiphoton laser ablation from vascular microstructure fabrication towards epithelial nephron engineering, and establishes a versatile approach for generating anatomically organized microscale tissue architecture within collagen hydrogels.