1. Institute of Biomaterial Science; Helmholtz-Zentrum Geesthacht; Kantstr. 55 14513 Teltow Germany
2. Berlin-Brandenburg Center for Regenerative Therapies; Föhrer Str 15 13353 Berlin Germany
3. Institute of Biochemistry and Biology; University of Potsdam; 14476 Potsdam-Golm Germany
4. Institute of Chemistry; University of Potsdam; 14476 Potsdam-Golm Germany
5. Max-Delbrueck-Center for Molecular Medicine; 13125 Berlin Germany
6. Humboldt-University Berlin; Institute for Biology; Berlin Germany