Ralf Reinhard Tönjes (RRT; German) is emeritus and senior scientist at Paul-Ehrlich-Institut (PEI), Federal Institute for Vaccines and Biomedicines, Division of Haematology, Cell and Gene Therapy, Section 6 Research Centre ATMP / Haematology, Subsection 6.3 Xenotransplantation, Langen, Germany.

RRT received his M.S. degree in Biology and Germanistics (1983) and his Ph.D. degree in Biology (1986) from Philipps University, Marburg, Germany. His thesis involved molecular cloning and analyses of histone genes and proteins for chromatin studies. As a researcher, he worked at Fraunhofer Institute, Hannover, Germany, and at Rockefeller University, New York, United States (1986-1991). His research interests included the liver specific regulation of genes in mutant as well as genetically modified mice.

At PEI, RRT was head of three sections 1991-2024. He was in charge of evaluations of medicinal products including human tissue preparations and xenogeneic cell therapeutics according to European and German legislations. Simultaneously, RRT’s area of experimental research was the safety of xenotransplantation. In particular, he concentrated on the characterization of porcine microbes including viruses and zoonotic agents as well as endogenous retroviruses and retroelements. In addition, RRT was involved in the non-clinical testing of xenotransplants using genetically modified animals.

In 1998, RRT founded the German working group for xenotransplantation (DAX) together with 
Dr. Joachim Denner.

Since 2002, RRT teaches as an adjunct professor and lecturer for biochemistry at Goethe University, Frankfurt/Main, Germany.

Since 2005, RRT was representative of Germany at World Health Organization (WHO) and at European Medicinal Agency (EMA) for global consultations on regulatory requirements for clinical trials of xenotransplantation. Since 2008, RRT was German representative for Tissues & Cells (T&C) at the European Commission (EC), National Competent Authorities (NCA), Substances of Human Origin (SoHO). Since 2012, RRT was German representative for T&C at the European Committee on Organ Transplantation (CD-P-TO), European Directorate for the Quality of Medicines & HealthCare (EDQM), Council of Europe (CoE). Since 2022, RRT was German Member of SoHO Network, SoHO National Focal Point for Blood, Human Organs, MAR and/or Tissues and Cells.Since 2023, RRT was expert for T&C and Member of SoHO Network Coordination Committee (NCC) within the SoHO National Focal Points. 

Since 2024, at CD-P-TO, EDQM, CoE, RRT is head of a working group on xenotransplantation.