Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids

3D tumor spheroids have arisen in the last years as potent tools for the in vitro screening of novel anticancer therapeutics. Nevertheless, to increase the reproducibility and predictability of the data originated from the spheroids it is still necessary to develop or optimize the techniques used fo...

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Main Authors: Daniel N. Silva, Elisabete C. Costa, Carolina F. Rodrigues, Duarte de Melo-Diogo, Ilídio J. Correia, André F. Moreira
Format: Article
Language:English
Published: MDPI AG 2020-12-01
Series:International Journal of Molecular Sciences
Subjects:
Online Access:https://www.mdpi.com/1422-0067/22/1/266
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author Daniel N. Silva
Elisabete C. Costa
Carolina F. Rodrigues
Duarte de Melo-Diogo
Ilídio J. Correia
André F. Moreira
author_facet Daniel N. Silva
Elisabete C. Costa
Carolina F. Rodrigues
Duarte de Melo-Diogo
Ilídio J. Correia
André F. Moreira
author_sort Daniel N. Silva
collection DOAJ
description 3D tumor spheroids have arisen in the last years as potent tools for the in vitro screening of novel anticancer therapeutics. Nevertheless, to increase the reproducibility and predictability of the data originated from the spheroids it is still necessary to develop or optimize the techniques used for spheroids’ physical and biomolecular characterization. Fluorescence microscopy, such as confocal laser scanning microscopy (CLSM), is a tool commonly used by researchers to characterize spheroids structure and the antitumoral effect of novel therapeutics. However, its application in spheroids’ analysis is hindered by the limited light penetration in thick samples. For this purpose, optical clearing solutions have been explored to increase the spheroids’ transparency by reducing the light scattering. In this study, the influence of agitation conditions (i.e., static, horizontal agitation, and rotatory agitation) on the <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> methods’ clearing efficacy and tumor spheroids’ imaging by CLSM was characterized. The obtained results demonstrate that the <i>Clear<sup>T</sup></i> method results in the improved imaging of the spheroids interior, whereas the <i>Clear<sup>T2</sup></i> resulted in an increased propidium iodide mean fluorescence intensity as well as a higher signal depth in the Z-axis. Additionally, for both methods, the best clearing results were obtained for the spheroids treated under the rotatory agitation. In general, this work provides new insights on the <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> clearing methodologies and their utilization for improving the reproducibility of the data obtained through the CLSM, such as the analysis of the cell death in response to therapeutics administration.
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spelling doaj.art-99cbe13c25b34eb3a18859c88aafc5f32023-11-21T03:00:01ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672020-12-0122126610.3390/ijms22010266Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D SpheroidsDaniel N. Silva0Elisabete C. Costa1Carolina F. Rodrigues2Duarte de Melo-Diogo3Ilídio J. Correia4André F. Moreira5CICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, PortugalCICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, PortugalCICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, PortugalCICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, PortugalCICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, PortugalCICS-UBI—Health Sciences Research Centre, Universidade da Beira Interior, 6200-506 Covilhã, Portugal3D tumor spheroids have arisen in the last years as potent tools for the in vitro screening of novel anticancer therapeutics. Nevertheless, to increase the reproducibility and predictability of the data originated from the spheroids it is still necessary to develop or optimize the techniques used for spheroids’ physical and biomolecular characterization. Fluorescence microscopy, such as confocal laser scanning microscopy (CLSM), is a tool commonly used by researchers to characterize spheroids structure and the antitumoral effect of novel therapeutics. However, its application in spheroids’ analysis is hindered by the limited light penetration in thick samples. For this purpose, optical clearing solutions have been explored to increase the spheroids’ transparency by reducing the light scattering. In this study, the influence of agitation conditions (i.e., static, horizontal agitation, and rotatory agitation) on the <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> methods’ clearing efficacy and tumor spheroids’ imaging by CLSM was characterized. The obtained results demonstrate that the <i>Clear<sup>T</sup></i> method results in the improved imaging of the spheroids interior, whereas the <i>Clear<sup>T2</sup></i> resulted in an increased propidium iodide mean fluorescence intensity as well as a higher signal depth in the Z-axis. Additionally, for both methods, the best clearing results were obtained for the spheroids treated under the rotatory agitation. In general, this work provides new insights on the <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> clearing methodologies and their utilization for improving the reproducibility of the data obtained through the CLSM, such as the analysis of the cell death in response to therapeutics administration.https://www.mdpi.com/1422-0067/22/1/266<i>Clear<sup>T</sup></i><i>Clear<sup>T2</sup></i>confocal microcopypropidium iodidetumor spheroids
spellingShingle Daniel N. Silva
Elisabete C. Costa
Carolina F. Rodrigues
Duarte de Melo-Diogo
Ilídio J. Correia
André F. Moreira
Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
International Journal of Molecular Sciences
<i>Clear<sup>T</sup></i>
<i>Clear<sup>T2</sup></i>
confocal microcopy
propidium iodide
tumor spheroids
title Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
title_full Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
title_fullStr Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
title_full_unstemmed Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
title_short Influence of <i>Clear<sup>T</sup></i> and <i>Clear<sup>T2</sup></i> Agitation Conditions in the Fluorescence Imaging of 3D Spheroids
title_sort influence of i clear sup t sup i and i clear sup t2 sup i agitation conditions in the fluorescence imaging of 3d spheroids
topic <i>Clear<sup>T</sup></i>
<i>Clear<sup>T2</sup></i>
confocal microcopy
propidium iodide
tumor spheroids
url https://www.mdpi.com/1422-0067/22/1/266
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