 In 2003, he got the professorship (Habilitation) in Molecular Human Genetics from Medical Faculty of Georg-August University in Göttingen and in 2006 Professorship for Stem Cell Biology from the Newcastle University Institute of Human Genetics.In 2009, he created human sperm-like cells from male stem cells in the laboratory for the first time.Previously, in 2006, he used sperm created from embryonic stem cells to impregnate mice.