Geert studied DNA damage repair and apoptosis in spermatogenesis during his PhD and his research still focuses on genome stability maintenance and development of germ cells. He was part of the team that published the first transcriptome of adult human male germ cells. This formed the basis for a novel research line on the role of germ cell-specific genes in the development and treatment of cancer. Moreover, his expertise also entails oocytes and early human embryology. For instance, his team recently discovered a miRNA that is specifically secreted by, and aids implantation of, good quality (euploid) human embryos and found that aging oocytes suffer from mitochondrial dysfunction. Geert has also unravelled two separate mechanisms that lead to human meiotic arrest and investigated the changing DNA damage response during spermatogonial differentiation using CRISPR-CAS and in vitro male germline stem cell culture systems. Geert is actively involved in mimicking the somatic male gonadal niche of Sertoli cells and how that directs spermatogenesis, and has recently started to use human induced pluripotent stem cells as in vitro models to study male gametogenesis and is particularly interested in meiotic progression.
Geert is regularly invited as speaker on science symposiums for clinicians or lay-men, panel discussions and public debates. He is BKO certified and teaches in many courses for medicine, biology or medical biology (undergraduate and PhD) students.