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31.01.2022The Electron Cryomicroscopy Unit of the CCiTUB has collaborated with IBEC and ICMS in the development of a method for preparing microfluidic chips for Transmission Electron Microscopy
The Electron Cryomicroscopy Unit of the CCiTUB has collaborated with researchers from the Institute of Bioengineering of Catalonia (IBEC) and the Department of Biomedical Engineering of the Institute for Complex Molecular Systems (ICMS) de la Eindhoven University of Technology in the development of a method for the imaging of microfluidic chips by Transmission Electron Microscopy.
Organ-on-a-Chip (OoC) technology has led to an important breakthrough in three-dimensional cell culture for Bioengineering over the past decade, and provides new insights into the development of disease and pre-clinical drug screening. Such platforms have been designed primarily for the manufacture and testing of new drugs, as well as to replace and/or reduce the use of experimental animals in toxicological studies and clinical trials. To date, Optical Microscopy and Fluorescence have been the most widely used methods for monitoring and extracting information from these models. Meanwhile, Transmission Electron Microscopy, despite its widespread use for the characterization of nanomaterials and biological samples, has remained an unexplored technique.
The result of this work has been the development of a method of preparation of microfluidic chips, without previous deconstruction, for their study by Transmission Electron Microscopy, and it has been published in the journal Applied Nano in the special edition Women in Science. The method describes the preparation of a model of tumor blood vessels-on-a-chip and the consecutive steps to preserve the endothelial cells lining microfluidic channel for the subsequent transformation of the chip into ultrathin sections. The protocol for preparing the whole chip for Transmission Electron Microscopy involves its chemical fixation, cryoprotection, propane immersion, freeze substitution and its embedding in acrylic resin. Afterwards, the areas of interest are manual trimmed and re-embed in acrylic resin. Finally, by means of ultramicrotomy, cross-sections of the microchannel with the cells cultured inside are obtained, which allows to observe the cellular adaptation to the geometry of the channel, as well as the close junctions of the endothelial cells. Thus, the developed method would facilitate the ultrastructural characterization of biological samples cultured in an OoC device by Transmission Electron Microscopy.