He began his studies at Macquarie University, where he received a Bachelor of Arts in 1973, an Honours degree in 1974, and a PhD in 1980. His doctoral thesis was titled "Olfaction and stress in mice."
After completing his studies, Mackay-Sim conducted research and taught at the University of Pennsylvania and the University of Wyoming in the United States. In 1987, he returned to Australia and joined Griffith University, where he focused his research on the olfactory system and adult stem cells.
He served as the founding Director of the National Centre for Adult Stem Cell Research and as Deputy Director of the Eskitis Institute for Cell and Molecular Therapies..[3][5]
↑Chehrehasa, Fatemeh; Ekberg, Jenny A. K.; Lineburg, Katie; Amaya, Daniel; Mackay-Sim, Alan; St. John, James A. (November 2011). "Two phases of replacement replenish the olfactory ensheathing cell population after injury in postnatal mice". Glia. 60 (2): 322–32. doi:10.1002/glia.22267. hdl:10072/45582. PMID22065423. S2CID7490951.