Synthesis and Optoelectronic Properties of New Methoxy-Substituted Diketopyrrolopyrrole Polymers

The introduction of functional groups with varying electron-donating/-withdrawing properties at the β-position of diketopyrrolopyrrole (DPP) has been shown to affect the optoelectronic properties of the polymers. We report the synthesis of a new diketopyrrolopyrrole monomer wherein a strong electron-donating substituent, a methoxy group, was incorporated at the β-position in an effort to modulate polymer properties. Homopolymers and co-polymers of the new β-methoxy DPP and nonderivatized DPP were synthesized, and their properties were measured by cyclic voltammetry and UV-vis-near-infrared. Density functional theory computations also were employed to predict the degree of planarity of β-methoxy oligomers to probe the significance of the newly introduced S-O conformational lock. The combined experimental and computational results showed a reduction in the gap between highest occupied molecular orbital/lowest unoccupied molecular orbital levels, a redshift toward the near-infrared region, and an increased planarity in the β-methoxy polymers

Subfractionation of Differentiating Human Embryonic Stem Cell Populations Allows the Isolation of a Mesodermal Population Enriched for Intermediate Mesoderm and Putative Renal Progenitors

Human embryonic stem (ES) cells are pluripotent and are believed to be able to generate all cell types in the body. As such, they have potential applications in regenerative therapy for kidney disease. However, before this can be achieved, a protocol to differentiate human ES cells to mesodermal renal progenitor lineages is required. Reduction of serum concentration and feeder layer density reduction cultures were used to differentiate human ES cells for 14 days. Differentiated ES cells were then fractionated by flow cytometry based on expression of the markers CD24, podocalyxin, and GCTM2 to isolate putative renal cells. These cells up-regulated the expression of the renal transcription factors PAX2, LHX1, and WT1 when compared with unfractionated human ES cells. Immunohistochemical assays confirmed that a subset of cells within this fraction co-expressed nuclear WT1 and PAX2 proteins. Transcriptome profiling also showed that the most differentially up-regulated genes in this fraction preferentially associated with kidney development in comparison with any other lineage. When compared with a transcriptome profile database of urogenital development (GUDMAP), the top 200 differentially up-regulated genes in this fraction strongly clustered into a group of genes associated with the metanephric mesenchyme at E11.5 and the corticonephrogenic interstitium at E15.5 of murine kidney development. Hence, this approach confirms an ability to direct human ES cells toward a renal progenitor state

Analysis of early nephron patterning reveals a role for distal RV proliferation in fusion to the ureteric tip via a cap mesenchyme-derived connecting segment

While nephron formation is known to be initiated by a mesenchyme-to-epithelial transition of the cap mesenchyme to form a renal vesicle (RV), the subsequent patterning of the nephron and fusion with the ureteric component of the kidney to form a patent contiguous uriniferous tubule has not been fully characterized. Using dual section in situ hybridization (SISH)/immunohistochemistry (IHC) we have revealed distinct distal/proximal patterning of Notch, BMP and Wnt pathway components within the RV stage nephron. Quantitation of mitoses and Cyclin D1 expression indicated that cell proliferation was higher in the distal RV, reflecting the differential developmental programs of the proximal and distal populations. A small number of RV genes were also expressed in the early connecting segment of the nephron. Dual ISH/IHC combined with serial section immunofluorescence and 3D reconstruction revealed that fusion occurs between the late RV and adjacent ureteric tip via a process that involves loss of the intervening ureteric epithelial basement membrane and insertion of cells expressing RV markers into the ureteric tip. Using Six2-eGFPCre × R26R-lacZ mice, we demonstrate that these cells are derived from the cap mesenchyme and not the ureteric epithelium. Hence, both nephron patterning and patency are evident at the late renal vesicle stage