Jon Vogel

Publications (2)7.09 Total impact

• Article: In vivo synthesis and secretion of erythropoietin by genetically modified primary human keratinocytes grafted onto immunocompromised mice.

  Frank Scheidemann, Jean-Philippe Therrien, Jon Vogel, Wolfgang Pfützner
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  ABSTRACT: The skin is an easily accessible tissue with a high blood flow facilitating the distribution of secreted peptides. These features make it a very intriguing target to serve as a biofactory releasing a systemically needed factor, such as erythropoietin (EPO). To evaluate the potential of human keratinocytes (KC) to systemically synthesize EPO, EPO-transduced KC were grafted onto immunocompromised mice and EPO secretion was followed by serum ELISA. Furthermore, we assessed if topical colchicine application would select for enriched percentages of KC expressing the multi-drug resistance (MDR) gene as a selectable gene connected to the EPO gene (measured by fluorescence-activated cell sorting (FACS)-analysis) and result in enhanced EPO production (determined by ELISA). Transduced KC showed stable EPO production in vivo during a 6-month observation period, pointing to engraftment of EPO-secreting KC progenitor cells. When adding colchicines the number of EPO/MDR+ KC were significantly enriched, both in skin grafts (in vivo) and in skin equivalents (in vitro). Of note, this did not result in enhanced EPO production. Rather, while EPO secretion was substantially increased in transduced KC grown as monolayers and selected with colchicine, it was reduced by more than 50% in both colchicine-treated skin grafts and skin equivalents. Keratinocytes carry the potential to serve as a genetically modified biofactory synthesizing human EPO. In vivo gene selection does not allow to select for increased EPO secretion, most likely because of altered secretory activity of transduced KC in the stratified, differentiated epidermis. Thus, further studies are necessary to optimize the release of EPO by genetically modified KC.
  Experimental Dermatology 11/2009; 19(3):289-97. · 3.54 Impact Factor
• Article: The skin as a biofactory for systemic secretion of erythropoietin: potential of genetically modified keratinocytes and fibroblasts.

  Frank Scheidemann, Maria Löser, Andrea Niedermeier, Arno Kromminga, Jean-Philippe Therrien, Jon Vogel, Wolfgang Pfützner
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  ABSTRACT: The skin is an interesting target tissue for gene therapy applications because of its ready accessibility. One possibility would be to utilize the genetically modified skin as a biofactory secreting a systemically needed product, such as erythropoietin (EPO). Keratinocytes (KC) and fibroblasts (FB) were transduced with a retroviral vector encoding human EPO. Gene transfer efficiency was assessed by real-time PCR analysis and flow cytometry of transduced cells. In addition, EPO synthesis and secretion were analysed by quantifying the amount of RNA and secreted protein in both monolayer cultures and skin equivalents (SE). When cultured as a monolayer, EPO-KC synthesized significantly more EPO than EPO-FB, as shown by quantitatively measuring the amount of secreted protein and RNA. This correlated with an increased EPO-vector incorporation in KC compared with FB, demonstrated by determining both the percentage of transduced cells and the average transgene copy number per cell. In addition, in transduced cell cultures enriched to equally high percentages of EPO+ cells, KC showed a higher activity of EPO secretion than FB. Finally, when assembled in a SE, EPO-KC secreted significantly higher amounts of EPO than EPO-FB, although reduced secretory activity of EPO-KC monolayers grown in high calcium concentrations suggested that in stratified epidermis differentiated KC secrete less EPO than non-differentiated KC. In summary, while both transduced KC and FB are able to synthesize and secrete human EPO, KC show higher potential in serving as possible target cells for therapeutic substitution with EPO, probably because of improved transduction rates and increased secretory activity.
  Experimental Dermatology 07/2008; 17(6):481-8. · 3.54 Impact Factor