Engineering Podocyte Microenvironments

The scientific results of this study will contribute to current understanding of renal physiology and function, promote advances in treatments for renal dysfunction and failure, and provide critical knowledge in moving towards the long-term goal of developing reparative ex vivo renal tissue for future patient therapies. Discrete cell-cell and cell-matrix interactions within the developing and mature kidney result from defined cellular crosstalk between distinct, adjacent cell populations. These interactions, between podocytes and endothelial cells, are critical to establishing and maintaining glomerular filtration function. This project is founded upon transdisciplinary research to delineate specific renal repair mechanisms within the kidney glomerulus and support the TIRN Research Objectives to eventually generate transplantable tissues. The proposed research is built upon conditional knockdown and knockout rodent models of podocyte vascular endothelial growth factor (VEGF) expression that demonstrate a central role of VEGF in maintaining renal filtration function; loss of this expression contributes to progression of renal disease. We have also found VEGF bound to renal extracellular matrix (ECM) within our bioartificial three-dimensional scaffolds, suggesting that the structural presentation of VEGF within the ECM may influence cellular function. Our specific research goal is to delineate the cellular crosstalk between podocytes and endothelial cells within bio-original extracellular matrix scaffolds and biosynthetic hydrogels build from renal extracellular matrix. The hypothesis to be tested is that variation of ECM consistency--and specifically the degree of VEGF within the biochemical milieu--will influence the fate and phenotype of podocytes and the degree of their interaction with glomerular endothelial cells. We use innovative and novel bioengineering techniques to manipulate the three-dimensional ECM architecture and study the resulting cellular phenotype. In Aim 1, we utilize our core technology by developing renal ECM scaffolds from donor rodent kidneys and modulate the level of growth factors retained within the scaffold. By using temperature-sensitive podocytes that differentiate only when cultured at a permissive temperature or primary cells isolated from transgenic mice, interaction with endothelial cells will be assessed in response to changing matrix conditions. In Aim 2, we develop novel hydrogels containing renal extracellular matrix components, proteins and growth factors. These hydrogels can be shaped to evaluate cell-cell crosstalk via a multitude of geometries. Together, these studies are aimed at delineating the role of cellular organization and crosstalk between defined biochemical boundaries of the renal ECM in directing cellular morphology and cell-cell interactions within the glomerulus. Ultimately, the scientific results of this study will contribute to current understanding of renal physiology and function, promote advances in treatments for renal dysfunction and failure, and provide critical knowledge in moving towards the long-term goal of developing reparative ex vivo renal tissue for future patient therapies.