Stephen received his PhD in Pathology (Neurosciences) in 1992 from the Albert Einstein College of Medicine in New York City. After postdoctoral work in central nervous system gene therapy, neural transplantation and neural stem cell biology at UCSD with Professor Fred “Rusty” Gage, he moved to the UK in 1996 and was appointed a Lecturer in Biomolecular Sciences at King's College London in 1998.
Over the past 20 years, Stephen’s research group has been at the forefront of human stem cell research. From 2002-2009 he was the Director of the Stem Cell Biology Laboratory. Together with Professor Peter Braude and Dr Susan Pickering, his group was the first to deposit a human ES cell line into the UK Stem Cell Bank.
In September 2009, he was appointed the Global Director for Research and Development for Cell Technologies at GE Healthcare. He was actively involved with the UK Department of Health and with the Minister for Public Health in the consultation with both Houses of Parliament that led to the passage of the Human Embryo Bill of 2009 and the inclusion of new forms of animal-human embryos within primary legislation. Stephen was the Stem Cell Expert and a Member of the UK Gene Therapy Advisory Committee (GTAC) at the Department of Health from 2006-2012 and was the Focal Point for Regenerative Medicine, Drug Discovery and Modernization of Traditional Chinese Medicine in China for the UK Department of Business, Innovation and Skills from 2006-2009, and is a member of the Scientific Advisory Committee of the Canadian Centre for the Commercialization of Regenerative Medicine.
In the summer of 2013, Stephen was appointed Chief Scientist for Cellular Sciences, GE Healthcare Life Sciences, and is responsible for long-term global research strategy for technology development in cell therapy, regenerative medicine, cellular technologies, in vivo diagnostic imaging and molecular pathology/personalized medicine. He left full-time employment with GE in Feb 2015 but is still a part-time Senior Consultant in Cellular Sciences and Regenerative for GE Healthcare Life Sciences. In addition, Stephen also serves as the Director of SLM Blue Skies Innovations Ltd, providing expert analysis in emerging healthcare technologies for the life sciences investment community.