Abstract
Human pluripotent stem cells have the potential to serve as a model of organ development and disease when grown in a three-dimensional (3D) structure. Human kidney development results from the reciprocal inductive interactions involving the metanephric mesenchyme (future excretory component of the kidney) and the ureteric bud (future collecting system). One of the challenges in creating kidney organoids is recapitulating the complex interactions between these primordial structures. Prior studies have shown methods to achieve either metanephric mesenchyme or ureteric bud lineage commitment from human induced pluripotent stem cells (hiPSC); however, a single protocol to achieve both lineages simultaneously is in need of further assessment. The goals of these studies were to expand a well-characterized bank of hiPSC, and to test a self-organizing differentiation protocol to determine if commitment to metanephric mesenchyme and ureteric bud precursors could be obtained in a combined culture system using either transwells or a 3D culture system. Studies focused on evaluating directed differentiation of hiPSC toward metanephric and ureteric bud lineages and recapitulating kidney development. The collection of cells was performed at select time points for gene expression analysis using quantitative PCR (qPCR) and at study endpoint for histologic analysis and immunohistochemistry. hiPSC were expanded and cryopreserved with characterization demonstrating pluripotency (endoderm, mesoderm, and ectoderm) by qPCR. When hiPSC were directed toward renal lineage differentiation, gene expression studies showed upregulation of the mesodermal marker brachyury, and markers of anterior and posterior intermediate mesoderm suggesting differentiation toward ureteric bud and metanephric mesenchyme phenotypes, respectively. Differentiated hiPSC formed tubules resembling early kidney development under both culture conditions. Analysis of renal developmental markers by immunohistochemistry showed similar expression patterns. The results of these studies support a differentiation protocol that recapitulates early stages of renal development.