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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

The present protocol provides a step-by-step procedure for rapid and simultaneous optical clearing, muti-round labeling, and 3D volumetric reconstruction of tens of postmortem human brain sections by combining the (SWITCH - H2O2 - Antigen Retrieval - 2,2'-thiodiethanol [TDE]) SHORT tissue transformation technique with light-sheet fluorescence microscopy imaging in a routinely high-throughput protocol.

Abstract

Despite the numerous clearing techniques that emerged in the last decade, processing postmortem human brains remains a challenging task due to its dimensions and complexity, which make imaging with micrometer resolution particularly difficult. This paper presents a protocol to perform the reconstruction of volumetric portions of the human brain by simultaneously processing tens of sections with the SHORT (SWITCH - H2O2 - Antigen Retrieval - 2,2'-thiodiethanol [TDE]) tissue transformation protocol, which enables clearing, labeling, and sequential imaging of the samples with light-sheet fluorescence microscopy (LSFM). SHORT provides rapid tissue clearing and homogeneous multi-labeling of thick slices with several neuronal markers, enabling the identification of different neuronal subpopulations in both white and grey matter. After clearing, the slices are imaged via LSFM with micrometer resolution and in multiple channels simultaneously for a rapid 3D reconstruction. By combining SHORT with LSFM analysis within a routinely high-throughput protocol, it is possible to obtain the 3D cytoarchitecture reconstruction of large volumetric areas at high resolution in a short time, thus enabling comprehensive structural characterization of the human brain.

Introduction

Analyzing the 3D molecular organization and cytoarchitecture of large volumes of the human brain requires optical transparency of specimens, achieved through protocols with extensive processing time. Optical clearing techniques were developed to minimize heterogeneity in refractive index (RI) within the tissues, thereby reducing light scattering and increasing the light penetration depth for high-resolution imaging1,2,3,4,5. Current advances in clearing and deep tissue-labeling methods allow volumetric imag....

Protocol

Formalin-fixed human tissue samples were provided by the Department of Neuropathology at the Massachusetts General Hospital (MGH) Autopsy Service (Boston, USA). Written consent was obtained from healthy participants prior to death, following IRB-approved tissue collection protocols from the Partners Institutional Biosafety Committee (PIBC, protocol 2003P001937). The authorization documents are kept with the MGH Autopsy Services in Boston, MA, United States, and are available upon request.

Representative Results

The protocol described here enables the simultaneous treatment of multiple slices, ranging in thickness from 100 µm to 500 µm, using the SHORT method. This approach significantly reduces the overall processing time for the entire procedure. In this work, we provide a comprehensive description of the entire pipeline (Figure 1) for processing multiple postmortem human brain thick sections simultaneously and we demonstrate the protocol on 24 slices at once (Figure.......

Discussion

High-resolution imaging and 3D reconstruction of large human brain areas require mechanical tissue sectioning followed by optical clearing and immunolabeling of single slices. The protocol presented here describes how the SHORT tissue transformation method can be used for rapid and simultaneous processing of multiple human brain thick sections for 3D brain reconstruction with a subcellular resolution with LSFM.

Unlike other approaches, with the SHORT method the clearing and multi-labeling step.......

Acknowledgements

We thank Bruce Fischl, Massachusetts General Hospital, A.A. Martinos Center for Biomedical Imaging, Department of Radiology, for providing the human brain specimens analyzed in this study. This project received funding from the European Union's Horizon 2020 Research and Innovation Framework Programme under grant agreement No. 654148 (Laserlab-Europe), from the European Union's Horizon 2020 Framework Programme for Research and Innovation under the Specific Grant Agreement No. 785907 (Human Brain Project SGA2) and No. 945539 (Human Brain Project SGA3), from the General Hospital Corporation Center of the National Institutes of Health under award number U01 MH1170....

Materials

NameCompanyCatalog NumberComments
2,2'-thiodiethanolMerck Life Science S.R.L.166782
Acetamide >= 99.0% (GC)Merck Life Science S.R.L.160
Agarose High EEOMerck Life Science S.R.L.A9793
Boric AcidMerck Life Science S.R.L.B7901
Compressome VF-900-0Z MicrotomePrecisionary/
CoverslipsLaserOptex/customized
Ethylenediaminetetraacetic acid disodium salt dihydrateMerck Life Science S.R.L.E5134
GlutaraldehydeMerck Life Science S.R.L.G7651
GlycineSanta Cruz BiotechnologySC_29096
Hydrogen Peroxide 30%Merck Life Science S.R.L.
Incubator ISS-4075Lab companion /
Light-sheet fluorescence microscopy (LSFM)//custom-made
Loctite AttakHenkel Italia srl/
Microscope slidesLaborchimica/customized
Phospate buffer saline tabletMerck Life Science S.R.L.P4417
Picodent TwinsilPicodent13005002out of production
Potassium Hydrogen PhtalateMerck Life Science S.R.L.P1088
Sodium AzideMerck Life Science S.R.L.S2002
Sodium Dodecyl SulfateMerck Life Science S.R.L.L3771
Sodium SulfiteMerck Life Science S.R.L.S0505
SpacersMicrolaser srlcustomized
Sputum Containers (dishes with screw lids)Paul Boettger GmbH & Co. KG07.061.2000
Tris BasePanReac AppliChem (ITW reagents)A4577,0500
Triton X-100Merck Life Science S.R.L.T8787
TubesSarstedt62 547254
Tween 20Merck Life Science S.R.L.P9416
Vibratome VT1000SLeica Biosystem/
Water bath MemmertWNB 7-45
Antibodies and Dyes
Alexa Fluor 488 AffiniPure Alpaca Anti-Rabbit IgG (H+L)Jackson Immuno Reasearch611-545-215Dilution used, 1:200
Alexa Fluor 488 AffiniPure Bovine Anti-Goat IgG (H+L)Jackson Immuno Reasearch805-545-180Dilution used, 1:200
Alexa Fluor 647 AffiniPure Alpaca Anti-Rabbit IgG (H+L)Jackson Immuno Reasearch611-605-215Dilution used, 1:200
Anti-NeuN AntibodyMerck Life Science S.R.L.ABN91Dilution used, 1:100
Anti-Parvalbumin antibody (PV)Abcamab32895Dilution used, 1:200
Anti-Vimentin antibody [V9] - Cytoskeleton Marker (VIM)Abcamab8069Dilution used, 1:200
Calretinin Polyclonal antibodyProteinTech12278_1_APDilution used, 1:200
DAPIThermoFisherD3571Dilution used, 1:100
Donkey Anti-Mouse IgG H&L (Alexa Fluor 568)Abcamab175700Dilution used, 1:200
Donkey Anti-Mouse IgG H&L (Alexa Fluor 647)Abcamab150107Dilution used, 1:200
Donkey Anti-Rabbit IgG H&L (Alexa Fluor 568)Abcamab175470Dilution used, 1:200
Donkey Anti-Rat IgG H&L (Alexa Fluor 568) preadsorbedAbcamab175475Dilution used, 1:200
Goat Anti-Chicken IgY H&L (Alexa Fluor 488)Abcamab150169Dilution used, 1:500
Goat Anti-Chicken IgY H&L (Alexa Fluor 568)Abcamab175711Dilution used, 1:500
Goat Anti-Chicken IgY H&L (Alexa Fluor 647)Abcamab150171Dilution used, 1:500
Goat Anti-Rabbit IgG H&L (Alexa Fluor 488)Abcamab150077Dilution used, 1:200
Recombinant Alexa Fluor 488 Anti-GFAP antibodyAbcamab194324Dilution used, 1:200
Somatostatin Antibody YC7Santa Cruz Biotechnologysc-47706Dilution used, 1:200
Vasoactive intestinal peptide (VIP)ProteinTech16233-1-APDilution used, 1:200

References

  1. Costantini, I., Cicchi, R., Silvestri, L., Vanzi, F., Pavone, F. S. In-vivo and ex-vivo optical clearing methods for biological tissues: review. Biomedical Optics Express. 10 (10), 5251 (2019).
  2. Richardson, D. S., et al. Tissue clearing.

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Optical ClearingLight sheet Fluorescence MicroscopyLarge scale Human Brain Imaging3D CytoarchitectureVolumetric ReconstructionSHORT Tissue Transformation ProtocolRapid ClearingHomogeneous Multi labelingNeuronal SubpopulationsMicrometer ResolutionHigh throughput Protocol

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