 Walles completed his specialist training in thoracic surgery at various established thoracic surgery units in 2008 and is recognized as "Fellow of the European Board of Thoracic and Cardiovascular Surgeons".He was visiting scientist at the Fraunhofer-Institute for Interfacial Engineering and Biotechnology in Stuttgart from 2005 to 2012.He received the habilitation at the University of Tübingen in 2009.