Ralf R. Tönjes, PhD
Paul Ehrlich Institute, Division of Medical Biotechnology, Section of Xenogeneic Cell
Therapeutics, Paul-Ehrlich-Straße 51-59, D-63225 Langen, Germany

Ralf R. Tönjes (German) is research scientist and group leader at Paul-Ehrlich-Institute (PEI), Federal Agency for Sera and Vaccines, Division of Medical Biotechnology, Langen, Germany.
He received his M.S. degree in biology and germanistics (1983) and his PhD degree in biology (1986) from the University of Marburg, Germany. His thesis involved the molecular analysis of histone genes and proteins for chromatin studies. Subsequently, he worked as a researcher at Fraunhofer-Institute, Hannover, and was on sabbatical leave at Rockefeller University, New York, United States in 1990 and 1991. His research interests span several experimental systems including the liver specific regulation of genes in mutant and transgenic mice.
Ralf Tönjes is section head at PEI since 1991. As such he is concerned with recombinant DNA derived vaccines, with the field of xenotransplantation and with allogeneic human transplants. He founded the German working group for xenotransplantation (DAX) together with Dr. Denner in 1998. He teaches as an associate professor at Frankfurt Johann Wolfgang Goethe-University, Institute of Biochemistry. He passed his habilitation in 2002.

Ralf Tönjes’ area of research is focused on endogenous retroviruses and retroelements of men and animals. He has more than 60 publications including peer-reviewed scientific articles, reviews and patents. He is the supervisor of four PhD students at present.

2006 - Stem cell signatures as a tool for quality control of innovative medicinal products

Paul-Ehrlich-Institut (PEI) takes care of licensing, testing, batch controls and clinical
trials of biologic medicinal products for the German and European market. PEI is a
competent authority linked to the European Agency for the Evaluation of Medicinal
Products, EMEA, London. At the institute molecularly based standards and an
experimental system for the approval of medicinal products such as human stem cell
(SC) based therapeutics are generated. With regard to the upcoming EU regulatory
framework on advanced therapies there are urgent needs to define the quality, safety
and efficacy of SC. These criteria are indispensable for the validation of industrial
production and clinical trials in humans and may serve for the approval and licensing
of cell therapeutic and tissue engineering products in the future.
We are working on the development of new methods and procedures to realize
quality controls of SC. Relatively little is known about the genetic program of SC and
their genetic signatures. Particularly the functions, dynamics and networks of
expressed genes and vital protein complexes in tissue-specific SC differentiation
should be evaluated.
One aim is the use of microarray technologies and ‘Omic’ platforms as fast analysis
tools to identify typical SC markers. Firstly, the specific gene expression profile of
hematopoietic (HSC) and mesenchymal stem cells (MSC) will be defined and
compared to the expression profile of differentiated lymphoid and myeloid cells
derived from hematopoietic stem cells.
An important clinical application could be the usage of chondrocytes derived from
MSC for articular injuries. The goal of our second project is the detection of changes
in the gene expression profiles of MSC differentiating towards chondrocytes by
microarray analysis and to identify new markers.