Reciprocal Induction of Simple Organogenesis by Mouse Kidney Progenitor Cells in Three-Dimensional Co-Culture

Abstract

Kidney development is regulated by a coordinated reciprocal induction of metanephric mesenchymal (MM) and ureteric bud (UB) cells. Here, established MM and UB progenitor cell lines were recombined in three-dimensional Matrigel implants in SCID mice. Differentiation potential was examined for changes in phenotype, organization, and the presence of specialized proteins using immunofluorescence and bright-field and electron microscopy. Both cell types, when grown alone, did not develop into specialized structures. When combined, the cells organized into simple organoid structures of polarized epithelia with lumens surrounded by capillary-like structures. Tracker experiments indicated the UB cells formed the tubuloid structures, and the MM cells were the source of the capillary-like cells. The epithelial cells stained positive for pancytokeratin, the junctional complex protein ZO-1, collagen type IV, as well as UB and collecting duct markers, rearranged during transfection (RET), Dolichos biflorus lectin, EndoA cytokeratin, and aquaporin 2. The surrounding cells expressed α-smooth muscle actin, vimentin, platelet endothelial cell adhesion molecule 1 (PECAM), and aquaporin 1, a marker of vasculogenesis. The epithelium exhibited apical vacuoles, microvilli, junctional complexes, and linear basement membranes. Capillary-like structures showed endothelial features with occasional pericytes. UB cell epithelialization was augmented in the presence of MM cell-derived conditioned medium, glial-derived neurotrophic factor (GDNF), hepatocyte growth factor (HGF), or fibronectin. MM cells grown in the presence of UB-derived conditioned medium failed to undergo differentiation. However, UB cell-derived conditioned medium induced MM cell migration. These studies indicate that tubulogenesis and vasculogenesis can be partially recapitulated by recombining individual MM and UB cell lineages, providing a new model system to study organogenesis ex vivo.

C-Kit+ Cells Isolated from Developing Kidneys Are a Novel Population of Stem Cells with Regenerative Potential

“…Additionally, studies on transgenic mice confirmed c-kit expression in hemangioblasts, MM, and also in the epithelial cells of the distal tubules, collecting ducts, ureter and bladder [44]. However, further studies on in vivo lineage tracing of endogenous c-kit + population would bring additional information whether c-kit + cells invade the condensing MM from outside, are a mesenchymal population of cells distinct from the MM cells that will became renal epithelia, or derive from some distinct MM progenitor cell [43,45-47]. …”

In Vivo Maturation of Functional Renal Organoids Formed from Embryonic Cell Suspensions

“…In normal renal development, cells of the ureteric bud (UB), an outgrowth of the Wolffian duct, invade and reciprocally interact with cells of the metanephric mesenchyme (MM) [6][7][8][9][10] to initiate nephron formation. The MM induces UB branching morphogenesis and is, in turn, induced to form neural cell adhesion molecule (NCAM) -positive and paired box gene 2 (Pax-2) -positive caps (four to five cells deep) around the advancing tips of the UB.…”

Kidney-Specific Microscaffolds and Kidney-Derived Serum-Free Conditioned Media Support In Vitro Expansion, Differentiation, and Organization of Human Embryonic Stem Cells

“…It has previously been shown that ureteric bud (UB) cell-derived conditioned medium induced metanephric mesenchyme (MM) cell migration. 36 Furthermore, exposure to conditioned media derived from UB and MM cell cultures after stage II (intermediate mesoderm) was effective in inducing the expression of MM and UB markers, respectively, at Stage III (renal lineage). Additionally, it was shown that the conditioned medium from UB cells of embryonic kidneys, when added to pretreated embryonic stem cell cultures, was shown to induce the renal lineages markers Pax2, WT-1, Pod-1, and E-cadherin by gene expression analysis and by FITC-DB (Dolichos biflorus) binding.…”