NRW International Graduate Research School Biotech

Bonn, Germany

NRW International Graduate Research School Biotech

Bonn, Germany
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Fustero S.,University of Valencia | Fustero S.,Research Center Principe Felipe | Rodrigo V.,Research Center Principe Felipe | Sanchez-Rosello M.,Research Center Principe Felipe | And 11 more authors.
Chemistry - A European Journal | Year: 2011

Fluor-in or out? Based on β,β-difluorinated cycloaliphatic amino acids, a library of new dipeptide nitriles was evaluated as human cathepsin inhibitors. The orientation of the fluorinated face relative to the protein structure of cathepsin B was elucidated by molecular modeling and NMR studies (see figure). For (R)-configured eutomers, the fluorine atoms are directed to the S2 pocket, whereas in (S)-configured distomers, the fluorinated face is solvent-exposed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lim T.-T.,University of Bonn | Lim T.-T.,NRW International Graduate Research School Biotech | Geisen C.,University of Bonn | Hesse M.,University of Bonn | And 6 more authors.
PLoS ONE | Year: 2013

Embryonic stem cells (ES) and induced pluripotent stem (iPS) cells represent promising tools for cell-based therapies and regenerative medicine. Nevertheless, implantation of ES cell derived differentiated cells holds the risk of teratoma formation due to residual undifferentiated cells. In order to tackle this problem, we used pluripotent stem cells consisting of ES and iPS cells of mouse genetically modified by lentiviral vectors (LVs) carrying herpes simplex virus thymidine kinase (HSV-TK) under the control of different promoters of pluripotency genes. Cells expressing TK in turn are eliminated upon administration of the prodrug ganciclovir (GCV). Our aim was to study the conditions required for a safe mechanism to clear residual undifferentiated cells but using low MOIs of lentiviruses to reduce the risk of insertional mutagenesis. Our in vitro data demonstrated that TK expression in pluripotent stem cells upon treatment with GCV led to elimination of undifferentiated cells. However, introduction of hygromycin resistance in the LV transduced ES cells followed by pre-selection with hygromycin and GCV treatment was required to abolish undifferentiated cells. Most importantly, transplantation of pre-selected ES cells that had been transduced with low MOI LV in mice resulted in no teratoma development after GCV treatment in vivo. Taken together, our data show that pre-selection of ES cells prior to in vivo application is necessary if vector integration events are minimized. The study presented here gives rise to safer use of pluripotent stem cells as promising cell sources in regenerative medicine in the future. © 2013 Lim et al.

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