Professor Ed Wu is an interdisciplinary scientist who designs both the software and hardware systems for the non-invasive, in vivo imaging of our cellular architecture.
Biomedical imagining has been one of the most powerful and advanced research areas in engineering. Current imaging technologies, such as CT (computerised tomography) and MRI (magnetic resonance imagining), allow clinicians to gain anatomical information of patients and help inform important medical decisions in hospitals every day. The diagnostic capabilities of these technologies, however, are limited by their resolution. They are only able to provide information on anatomical structures (for example organs and blood vessels), and might fail to detect early signs of diseases that occur at the molecular level.
Wu has developed a number of new techniques to allow us to get a glimpse of the inner workings of cells. One such methodology is manganese-enhanced MRI, which makes use of manganese ions as analogs of calcium ions.1 Calcium ions play crucial roles in cells by acting as the messenger in various signal transduction pathways. Uptake of these ions into cells is a key step in processes such as neuronal activation and muscle contraction. The movement of calcium ions can thus be used as a measure of cellular activity. By virtue of their similarity to calcium ions, manganese ions can be taken up by cells in a similar way. While they act as ‘body doubles’ of calcium ions, manganese ions are also paramagnetic and can be detected using MRI. Therefore, manganese ions can be injected as a tracer to enable us to monitor the activities of cells.
The resolution of conventional MRI is approximately 50 microns, which is larger than the size of a typical cell. To overcome this limitation, Wu has worked on diffusion kurtosis imaging. This involves the development of sophisticated mathematical models for the calculation of cellular complexity using the direction as well as the restriction of water diffusion inside biological systems. For example, water diffusion is more restricted in brain regions with a high cell density, compared to regions with a low cell density where water movement is less likely to be obstructed by membranes. Information such as cell density and cell size can thus be inferred through mathematical modelling of this water movement information provided by MRI.2 This method also eliminates the need of a contrast agent, and thus can potentially be used on humans in disease diagnoses.
Wu’s research group has recently made another major breakthrough in non-invasive imaging technologies. Using a similar approach to diffusion kurtosis imaging, Wu has developed a method for measuring changes in intracellular lipid storage by monitoring the diffusion of lipid protons. As lipids are consumed during metabolism, this method can be used to measure metabolic activities in cells. This bears important implications for the diagnosis and management of metabolic diseases, such as diabetes, by allowing us to understand the changes in lipid consumption and metabolism underlying these diseases. Wu will devote part of his tenure to further his research in this area. He will also devote part of his fellowship to develop MRI tracking of endogenous stem cells in our nervous system. This research will provide scientists with a biologically compatible technology for tracking the migration of stem cells during normal neural development as well as in disease conditions.
Wu obtained his bachelor’s degree from Tianjin University. After completing a master’s degree at the University of Wisconsin-Madison, he went on to the University of California-Irvine for his PhD studies. Wu had already become a faculty member of Columbia University before he received his PhD in 1993. He joined the Department of Electrical and Electronic Engineering at the University of Hong Kong in 2003 and was appointed to a professorship in 2007. (2012-13)
References:
1. Yang, J., and Wu, E.X. (2008). Detection of cortical gray matter lesion in the late phase of mild hypoxic-ischemic injury by manganese-enhanced MRI. Neuroimage. Jan; 39(2): 669-79.
2. Wu, E.X, and Cheung, M.M. (2010). MR diffusion kurtosis imaging for neural tissue characterization. NMR Biomed. Aug; 23 (&): 836-48. Review.
