Biofabrication of a Filtration Barrier by Integrating Electrospun Membranes and Flow in a Glomerular Co-Culture

The glomerular filtration barrier (GFB), composed of glomerular endothelial cells, podocytes, and the glomerular basement membrane (GBM), is essential for selective filtration in the kidney. Damage to any GFB component results in proteinuria and kidney failure. To model glomerular pathophysiology and test therapies, this study introduces an ex vivo GFB model using electrospun poly-L-lactic acid fibers that mimic the GBM. The fibers are functionalized with polydopamine and gelatin, then seeded with human glomerular endothelial cells and podocytes on opposite sides. This biomimetic setup supports monolayer formation, cell-type-specific marker expression, and appropriate morphology of both cell types, including those derived from human induced pluripotent stem cells (hiPSCs). The model demonstrates bidirectional cell-cell communication across the membrane. Permeability assays confirm size-selective dextran filtration. Under flow conditions in a custom 3D-printed micro-bioreactor, endothelial cells develop fenestrae-like structures, whereas podocytes form foot process-like extension features, which are often lacking in static in vitro systems. This platform replicates critical features of the native GFB and provides a robust system for studying glomerular function, disease mechanisms, and therapeutic responses. Moreover, incorporating hiPSC-derived podocytes enables exploration of patient-specific mutations and personalized treatment strategies in kidney disease.