■ Title : Hydrogel-based tissue imaging:
How materials science is revolutionizing neuroscience, biology, and medicine
■ Speaker : Prof. Jae-Byum Chang (Sungkyunkwan Univ.)
■ Date and time : 20th of February, 2018 (Tue) 16:00
■ Venue : Applied Engineering Department (W1-1) Room 2427
■ Abstract :
Our understanding on human organs is very limited. Human organs are made of millions of cells and the molecular profiles of cells, such as numbers and sub-cellular locations of various biomolecules (proteins, mRNAs, DNAs, etc.) are precisely controlled over an entire organ. As a result, extracting the complete profiles of biological molecules within an entire organ is essential to understanding the molecular mechanisms of organ function. To achieve such goal, new optical imaging technique, which can image multiple molecular species with a single-molecule resolution over a large volume, is needed.
We recently discovered that we could physically magnify specimens by embedding them in a dense swellable polymer, anchoring key biomolecules to the polymer mesh, and adding water to swell the polymer, a process we call ‘expansion microscopy’1. Despite the high isotropy of the expansion process, the initial polymer recipe enabled just 4-4.5x expansion, or roughly 60-70 nm spatial resolution. Ideally it would be possible to improve the expansion chemistry so as to enable, ultimately, the imaging of membrane boundaries, as well as protein complexes. Here, we report on an iterative ExM (iExM) chemistry that can achieve ~20x physical magnification of mouse brain tissues, or 20-nm lateral resolution on conventional optical microscopes2. As with the first version of ExM, iExM-processed samples are optically clear. Thus, iExM may be useful for imaging nanoscale neuronal structures such as synaptic clefts over entire neural circuits in intact mammalian tissues. Brain circuit mapping using iterative ExM may open up a variety of insights into the underpinnings of behavior, cognition, and disease. In addition, as iExM can be applied to various organs, such as heart, liver, pancreas, lung, intestine, they could be a very useful tool to study and diagnose various diseases, such as cancers and cardiovascular diseases.