2018.08.22
Chemical Landscape for Tissue Clearing Based on Hydrophilic Reagents
（Cell Rep. 2018 August 21;24:2196-2210. doi: 10.1016/j.celrep.2018.07.056）
Tainaka K1,2,3,20, Murakami TC1,20, Susaki EA1,2,4, Shimizu C2, Saito R5, Takahashi K6, Hayashi-Takagi A4,7, Sekiya H8, Arima Y9, Nojima S10, Ikemura M11, Ushiku T11, Shimizu Y12, Murakami M9, Tanaka KF13, Iino M8,14, Kasai H15,19, Sasaoka T16, Kobayashi K17, Miyazono K6, Morii E10, Isa T18, Fukayama M11, Kakita A5, Ueda HR1,2,19
1Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo
2Laboratory for Synthetic Biology, RIKEN Center for Biosystems Dynamics Research
3Department of System Pathology for Neurological Disorders, Brain Research Institute
4PRESTO, Japan Science and Technology Agency (JST)
5Department of Pathology, Brain Research Institute
6Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo
7Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University
8Department of Pharmacology, Graduate School of Medicine, The University of Tokyo
9Division of Psychoimmunology, Institute of Genetic Medicine, Graduate School of Medicine, Hokkaido University
10Department of Pathology, Osaka University Graduate School of Medicine
11Department of Pathology, Graduate School of Medicine, The University of Tokyo
12Laboratory for Cell-Free Protein Synthesis, RIKEN Center for Biosystems Dynamics Research
13Department of Neuropsychiatry, Keio University School of Medicine
14Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine
15Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo
16Department of Comparative and Experimental Medicine, Brain Research Institute
17Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine
18Department of Neuroscience, Graduate School of Medicine and Faculty of Medicine, Kyoto University
19International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo
20These authors contributed equally
Abstract
We describe a strategy for developing hydrophilic chemical cocktails for tissue delipidation, decoloring, refractive index (RI) matching, and decalcification, based on comprehensive chemical profiling. More than 1,600 chemicals were screened by a high-throughput evaluation system for each chemical process. The chemical profiling revealed important chemical factors: salt-free amine with high octanol/water partition-coefficient (logP) for delipidation, N-alkylimidazole for decoloring, aromatic amide for RI matching, and protonation of phosphate ion for decalcification. The strategic integration of optimal chemical cocktails provided a series of CUBIC (clear, unobstructed brain/body imaging cocktails and computational analysis) protocols, which efficiently clear mouse organs, mouse body including bone, and even large primate and human tissues. The updated CUBIC protocols are scalable and reproducible, and they enable three-dimensional imaging of the mammalian body and large primate and human tissues. This strategy represents a future paradigm for the rational design of hydrophilic clearing cocktails that can be used for large tissues.
