Professor Dr. Cornelius (Kees) Kluft, PhD

Prof. Dr. Kluft is the founder and CEO of GBS Leiden, and a renowned expert in haemostasis and human biomarkers. He was projectleader of projects of several large pharmaceutical companies, as well as different academic research organizations and charitable foundations supporting patient groups.
He started his career in haemostasis (fibrinolysis) at TNO (Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk Onderzoek) in 1972. Continuing as TNO’s Haemostasis specialist and division head of vascular medicine and connective tissue research and was one of the founders of TNO Pharma. He is chairman of the supervisory board of ECAT, external quality assessment organisation. He previously held positions as Professor in Thrombosis Research (University of Southern Denmark) and in Cardiovascular Biology (Catholic University, Italy).
After 33 years he left TNO, started GBS and continued working with the CHDR (Centre for Human Drug Research) as a biomarker specialist. Presently, he is also visiting professor at the University of Southern Denmark in Esbjerg University, in a joint programme on biocompatibility and contact activation.

Tel:      +31 (0)6 53 62 22 21


Dr. Ir. Martine van Essen-Hollestelle

Martine van Essen-Hollestelle  is Senior Scientist and Operational Officer at GBS with specialization in thrombosis and hemostasis. She started her career in hemostasis at Sanquin in 1998. In 2004 this study was finished with  a thesis called: “Factor VIII expression and regulation in health and disease”. After this project she worked as a Post-Doc in developing assays for in vitro and in vivo testing inhibitors against pancreatic cancer at the Wilhelmina Children Hospital. From 2007, she focused on thrombosis complication and the contribution of von Willbrand factor at the UMC Utrecht. After one year educating students at the Saxion University of Applied Sciences in 2010, she worked for several years at Sanquin Diagnostics at the laboratory of Coagulation and was responsible for the patient diagnostic. Furthermore, she is member of the Section Coagulation of the Dutch Foundation for Quality Assurance in Medical Laboratories (SKML).

Tel:      +31 (0)71 751 71 70

Mail:    m.

Dr. Dimitar Tasev, MD

Dimitar Tasev  is the Scientific officer at GBS specialized in functional cellular assays in the field of immunity, inflammation, neurodegeneration, stem cell and vascular cell biology.

He  was educated and worked as an MD in Macedonia until 2009 when he moved to the Netherlands to pursue a MSc degree in Biomedical Sciences. During  the two one-year research specializations in Advanced Immunology and Cardiovascular Research, he investigated the immunological aspects of multiple sclerosis and the role of endothelial progenitor cells in angiogenesis. Prior to his current position, he investigated the biological response of endothelial progenitor cells to hypoxia and inflammation in 3D matrices during angiogenesis as a PhD student at ICaR-VU, VUmc, Amsterdam. In the course of his stay in academia, he obtained broad knowledge of molecular biology  techniques, cell culture, tissue engineering and assay development.

Tel:      +31 (0)71 751 71 75