A Cell Culture System for the Structure and Hydrogel Properties of Basement Membranes: Application to Capillary Walls

In specialized capillary beds such as the kidney glomerulus, the sheet-like structure of the basement membrane (BM) in conjunction with opposing monolayers of endothelium and epithelium form the functioning filtration unit of the kidney. Using a novel cross-linking method on a collagen substrate, we have created a hydrogel scaffold to substitute for the BM. A simple casting method was used to create thin films of the hydrogel scaffold (1-5 mu m), that were suitable for long-term static culture, and supported cell attachment and long term cell viability similar to a standard type I collagen substrate. Bulk diffusion and protein permeability of the hydrogel scaffold were evaluated, in addition to its use in a perfusion chamber where it withstood hydraulic pressures typical for glomerular capillaries. This system thus provided a suitable cell substrate for the co-culture of renal epithelial podocytes and endothelial cells in a device that replicates the geometry of the in vivo juxtaposition of the two cell types in relation to their BM.