John Sled

Dr. John G. Sled (PhD, M.Eng) is a Senior Scientist in the Translational Medicine Program and Director of the Mouse Imaging Centre. He is also a Professor and Vice-Chair in the Department of Medical Biophysics at the University of Toronto.  

A major focus of his research is on diseases affecting the vascular system, the placenta, and early brain development. He has employed mouse models of disease in combination with advanced imaging technologies to understand how early life adversity affects fetal and post-natal development and, in particular, the brain. Dr. Sled is widely recognized for his contributions to the development of medical imaging technologies. He was the first to describe comprehensive quantitative magnetization transfer MRI in humans and is the author of the widely used neuroimaging software N3. He has also made contributions in the areas of MRI relaxometry, tissue microstructure / diffusion, perfusion, and morphometric techniques.  

Research

Dr. Sled’s research program at the Mouse Imaging Centre of The Hospital for Sick Children seeks, through the development and application of advanced imaging technologies in mice, to develop new diagnostic technologies, to understand human disease, and to understand complex biological systems.  

One area where his team has made recent progress is in the development of a new ultrasound method for early detection of pregnancy complications caused by abnormal blood flow in the placenta. This imaging method, which was first developed using experimental mice, has now been adapted for following pregnant women at risk for pregnancy complications. Another active area has been the development of MRI methods for monitoring fetal health.  

A particular interest has been to develop techniques for determining whether a fetus has an adequate supply of oxygen, needed for healthy brain development. This work links to a broader investigation by his group into the effects on brain development of early life adversities including an inadequate supply of oxygen or nutrients in utero, premature delivery, congenital conditions, acquired infections or diseases, toxicants in the environment, and drug exposures. The multidisciplinary nature of this work and the natural translation of many of the imaging techniques for use in humans has led him to work closely with clinical collaborators on many of these projects. 

Education

1995: B.A.Sc., University of British Columbia, Bachelor of Applied Science in Engineering Physics, with honours, Vancouver, British Columbia, Canada 

1997: M. Eng. McGill University, Masters of Engineering in biomedical Engineering, Dean’s honour list, Montreal, Quebec, Canada 

2001: Ph.D. McGill University, Doctor of Philosophy in Electrical Engineering, Dean’s honour list, Montreal, Quebec, Canada 

Employment

• 2001–2003: Postdoctoral Fellow, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada 
• 2003–2010: Scientist, Mouse Imaging Centre, Physiology and Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada 
• 2003–2009: Assistant Professor, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada 
• 2003–2018: Adjunct Professor, Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada 
• 2009–2015: Associate Professor, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada 
• 2010–Present: Senior Scientist, Mouse Imaging Centre, Translational Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada 
• 2014–Present: Adjunct Professor, Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario, Canada 
• 2014–Present: Vice-Chair, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada 
• 2015–Present: Professor, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Achievements

• 2001: D.W. Ambridge Doctoral Prize for the best thesis in Physical Sciences and Engineering, McGill University 
• 2001: Geddes Prize in Biomedical Engineering, McGill University 
• 2007: Sylvia Fedorak Prize (recognizes article) 
• 2013: Canadian Institutes of Health Research–Institute of Aging (CIHR-IA) Age+ Prize (recognizes article) 

1. J. Sled, G. Stortz, L. Cahill, N. Milligan, V. Ayyathurai, L. Serghides, E. Morgen, V. Servalli, C. Delp, C. McShane, A. Baschat, J. Kingdom, C. Macgowan. “Reflected hemodynamic waves influence the pattern of Doppler ultrasound waveforms along the umbilical arteries.” American Journal of Physiology – Heart and Circulatory Physiology, Vol. 316, Issue 5, pp. H1105-H1112, 2019. DOI 10.1152/ajpheart.00704.2018 PMID 30794433 
2. L.S. Cahill, Y.-Q. Zhou, J. Hoggarth, J.P. Lerch, M. Seed, C.K. Macgowan, J.G. Sled.  “Fetal brain sparing in a mouse model of chronic maternal hypoxia.” Cerebral Blood Flow and Metabolism, epub ahead of print, January 2017. DOI 10.1177/0271678X17750324 PMID 29271304 
3. A. Rahman, Y.-Q. Zhou, Y. Yee, J. Dazai, L. Cahill, J. Kingdom, C.K. Macgowan, J.G. Sled. “Ultrasound detection of altered placental vascular morphology based on hemodynamic pulse wave reflection.” American Journal of Physiology-Heart and Circulatory Physiology. Vol. 312, issue 5, pp.:H1021-H1029, 2017. PMID 28364018 DOI 10.1152/ajpheart.00791.2016 
4. R. Nossin-Manor, D. Card, C. Raybaud, M. Taylor, J.G. Sled. “Cereberal Maturation in the Early Preterm Period - A Magnetization Transfer and Diffusion Tensor Imaging Study Using Voxel Based Analysis.”  NeuroImage. Vol. 112, pp. 30-42, 2015. DOI 10.1016/j.neuroimage.2015.02.051 PMID 25731990 
5. L.S. Cahill, Y-Q. Zhou, M. Seed, C.K. Macgowan, J.G. Sled.  “Brain Sparing in Fetal Mice: BOLD MRI and Doppler Ultrasound Demonstrate Blood Redistribtuion during Hypoxia.”  Journal of Cerebral Blood Flow and Metabolism.  Vol. 34, issue 6, pp. 1082-1088, 2014.  DOI 10.1038/jcbfm.2014.62  PMID 24714036 

See all of John Sled's publications on Google Scholar and the National Library of Medicine.