A proteome comparison between human fetal and mature renal extracellular matrix identifies EMILIN1 as a regulator of renal epithelial cell adhesion

Cell-based approaches using tissue engineering and regenerative medicine to replace damaged renal tissue with 3D constructs is a promising emerging therapy for kidney disease. Besides living cells, a template provided by a scaffold based on biomaterials and bioactive factors is needed for successful kidney engineering. Nature's own template for a scaffolding system is the extracellular matrix (ECM). Research has focused on mapping the mature renal ECM; however, the developing fetal ECM matches more the active environment required in 3D renal constructs. Here, we characterized the differences between the human fetal and mature renal ECM using spectrometry-based proteomics of decellularized tissue. We identified 99 different renal ECM proteins of which the majority forms an overlapping core, but also includes proteins enriched in either the fetal or mature ECM. Relative protein quantification showed a significant dominance of EMILIN1 in the fetal ECM. We functionally tested the role of EMILIN1 in the ECM using a novel methodology that permits the reliable anchorage of native cell-secreted ECM to glass coverslips. Depletion of EMILIN1 from the ECM layer using siRNA mediated knock-down technologies does not affect renal epithelial cell growth, but does promote migration. Lack of EMILIN1 in the ECM layer reduces the adhesion strength of renal epithelial cells, shown by a decrease in focal adhesion points and associated stress fibers. We showed in this study the importance of a human renal fetal and mature ECM catalogue for identifying promising ECM components that have high implementation potential in scaffolds for 3D renal constructs.