Alan Mackay-Sim is a leader in stem cell research and cell transplantation therapy. His research on the regeneration of the sense of smell led to the first clinical trial of a therapy to treat human paraplegia in which the patient’s own olfactory cells were transplanted into their injured spinal cord. Stem cells from patient’s olfactory epithelia are used to understand diseases such as schizophrenia, Parkinson’s disease, Hereditary Spastic Paraplegia, and to develop new drug therapies.