As a graduate student, Dr Harmsen had supervised 20 students (international and domestic) who were studying Pharmacy BSc and MSc at Utrecht University. He then departed to the USA and as a postdoctoral research fellow at Memorial Sloan Kettering Cancer Center, he was also involved in day-to-day supervision. Furthermore, he was involved as an instructor for Bio-Pharmaceutical Sciences students and PhD students in a variety of topics including Advanced Drug Delivery and Targeting, BioTherapeutics and Drug Delivery Technologies.