Copolymerization of Epoxides with Carbon Dioxide Catalyzed by Iron–Corrole Complexes: Synthesis of a Crystalline Copolymer

Iron–corrole complexes were found to copolymerize epoxides with CO₂. The first iron-catalyzed propylene oxide/CO₂ copolymerization has been accomplished. Moreover, the glycidyl phenyl ether (GPE)/CO₂ copolymerization with this catalyst provided a crystalline material as a result of the isotactic poly­(GPE) moiety

<i>Eng</i>^−/− ESC-derived EBs plated on gelatin coated plates lack organized vessel structures.

<p>(A) PECAM-1 immunohistochemical staining of ESC-derived 11-day-old EBs plated on gelatin for 4 days displayed “organized”, “intermediate” or “dispersed” phenotype. (B) Quantification of wild type, <i>Eng</i>^+/−, and <i>Eng</i>^−/− ESC-derived 15-day-old EBs vascular phenotypes as they were defined in A.</p

<i>Eng</i> deficiency inhibits VEGF-induced sprouting of HUVEC spheroids.

<p>(A) Effect of shRNA-mediated depletion of <i>Eng</i> on VEGF-induced endothelial cell sprouting. HUVECs were transduced with lentivirus expressing endoglin shRNA overnight. HUVEC spheroids with deficient endoglin expression were embedded in collagen and stimulated with VEGF (50 ng/ml). A representative experiment is shown. (B) Quantitation of effects seen in (A). (C) Effect of TRC105 ENG antibody on VEGF-induced endothelial cell sprouting. HUVEC spheroids were embedded in collagen and stimulated with VEGF (50 ng/ml), TRC105 (10 µg/ml), or both overnight. As control antibody for experiments using TRC105, the Fc domain (MOPC-21) from Bio Express, West Lebanon, NH, was used. Pictures were taken by phase-contrast microscopy. Quantitative analysis of the mean total sprout length was performed on 10 spheroids per experimental group. <i>P</i>≤0.05. (D) VEGF-induced VEGFR2 phosphorylation at site 1175 and extracellular regulated kinase (ERK) mitogen activated protein (MAP) kinase phosphorylation was examined in shRNA-mediated <i>Eng</i> knockdown cells. Two bands were detected with the phosphor ERK MAPK antibodies with a molecular weight of 44 and 42 kDa; they represent ERK1 and ERK2 isoforms, respectively. Number sign (#) represents a background band, indicating the even loading for the experiment. Asterisks indicate the protein bands with expected size.</p

VEGF-induced angiogenesis is impaired in <i>Eng</i>^+/⁻ fetal metatarsal bones.

<p>Metatarsals of 17-day-old mouse fetuses were prepared from wild type and <i>Eng</i>^+/− mice, transferred to cell-culture plates, allowed to adhere, and then stimulated with VEGF (50 ng/ml). (A) Cultures were fixed and vessel-like structures were visualized by anti-PECAM-1 staining. Six bones were stimulated per experimental group and one representative picture of each group is shown. (B) VEGF addition stimulated the formation of vessel-like structures. No significant difference in the baseline vascular network formation was observed between wild type and <i>Eng</i>^+/− metatarsals. The induction of the vascular network of wild type metatarsals is significantly stronger than the network of <i>Eng</i>^+/− metatarsals. <i>P</i>≤0.05.</p

Expression of endothelial-specific markers during vascular development in EBs.

<p>(A) RT-PCR analysis of endothelial cell markers was performed on ESC and EBs cultured for the indicated number of days. Abbreviations: PECAM, platelet endothelial cell adhesion molecule; tie, tyrosine kinase with immunoglobulin-like loop and epidermal growth factor homology domain; VEGF, vascular endothelial growth factor receptor (B) The number of PECAM-1 positive cells was quantified by FACS analysis of the cell suspension of wild type, <i>Eng</i>^+/−, and <i>Eng</i>^−/− ESC-derived 11-day-old EBs. (C) RT-PCR analysis of pericyte-smooth muscle cell markers was performed on ESC and EBs cultured for the indicated number of days. PCR primers used in this Figure are available upon request. Abbreviations: <i>Aebp</i>, adipocyte enhancer binding protein; <i>Axl</i>, a receptor tyrosine kinase; <i>Smooth</i>; Smoothelin B; <i>Cspr</i>, cysteine- and glycine-rich protein; <i>Cspg</i>, chondroitin sulfate proteoglycan; <i>Cnn</i>, calpoin; <i>Pdgf,</i> platelet-derived growth factor, <i>Rgs</i>, regulator of G protein signaling.</p

Impaired vasculature in <i>Eng</i> null-mutation ESC-derived 11-day-old EBs.

<p>(A) <i>Eng</i>^+/− or <i>Eng</i>^−/− ESC lines form EBs with no difference when compared to EBs derived from wild type ESCs (B) PECAM-1 whole mount immunohistochemistry of representative wild type, <i>Eng</i>^+/−, and <i>Eng</i>^−/− ESC-derived 11-day-old EBs. Wild type ESC-derived EBs form a primitive vascular plexus. In contrast, <i>Eng</i>^−/− ESC-derived EBs form irregular vascular structures with endothelial cell clusters. Light microscopy of serial plastic sections of wild type, <i>Eng</i>^+/−; and <i>Eng</i>^−/− ESC-derived 11-day-old EBs stained as whole mount for PECAM-1. Black arrowhead indicates vessel like structures. Asterisk indicates endothelial cell clusters.</p