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Randleman JB, Zhang H, Asroui L, Tarib I, Dupps WJ, Scarcelli G. Subclinical Keratoconus Detection and Characterization Using Motion-Tracking Brillouin Microscopy. Ophthalmology 2024; 131:310-321. [PMID: 37839561 DOI: 10.1016/j.ophtha.2023.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/17/2023] Open
Abstract
PURPOSE To characterize focal biomechanical alterations in subclinical keratoconus (SKC) using motion-tracking (MT) Brillouin microscopy and evaluate the ability of MT Brillouin metrics to differentiate eyes with SKC from normal control eyes. DESIGN Prospective cross-sectional study. PARTICIPANTS Thirty eyes from 30 patients were evaluated, including 15 eyes from 15 bilaterally normal patients and 15 eyes with SKC from 15 patients. METHODS All patients underwent Scheimpflug tomography and MT Brillouin microscopy using a custom-built device. Mean and minimum MT Brillouin values within the anterior plateau region and anterior 150 μm were generated. Scheimpflug metrics evaluated included inferior-superior (IS) value, maximum keratometry (Kmax), thinnest corneal thickness, asymmetry indices, Belin/Ambrosio display total deviation, and Ambrosio relational thickness. Receiver operating characteristic (ROC) curves were generated for all Scheimpflug and MT Brillouin metrics evaluated to determine the area under the ROC curve (AUC), sensitivity, and specificity for each variable. MAIN OUTCOME MEASURES Discriminative performance based on AUC, sensitivity, and specificity. RESULTS No significant differences were found between groups for age, sex, manifest refraction spherical equivalent, corrected distance visual acuity, Kmax, or KISA% index. Among Scheimpflug metrics, significant differences were found between groups for thinnest corneal thickness (556 μm vs. 522 μm; P < 0.001), IS value (0.29 diopter [D] vs. 1.05 D; P < 0.001), index of vertical asymmetry (IVA; 0.10 vs. 0.19; P < 0.001), and keratoconus index (1.01 vs. 1.05; P < 0.001), and no significant differences were found for any other Scheimpflug metric. Among MT Brillouin metrics, clear differences were found between control eyes and eyes with SKC for mean plateau (5.71 GHz vs. 5.68 GHz; P < 0.0001), minimum plateau (5.69 GHz vs. 5.65 GHz; P < 0.0001), mean anterior 150 μm (5.72 GHz vs. 5.68 GHz; P < 0.0001), and minimum anterior 150 μm (5.70 GHz vs. 5.66 GHz; P < 0.001). All MT Brillouin plateau and anterior 150 μm mean and minimum metrics fully differentiated groups (AUC, 1.0 for each), whereas the best performing Scheimpflug metrics were keratoconus index (AUC, 0.91), IS value (AUC, 0.89), and IVA (AUC, 0.88). CONCLUSIONS Motion-tracking Brillouin microscopy metrics effectively characterize focal corneal biomechanical alterations in eyes with SKC and clearly differentiated these eyes from control eyes, including eyes that were not differentiated accurately using Scheimpflug metrics. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- J Bradley Randleman
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio.
| | | | - Lara Asroui
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Imane Tarib
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
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Hanio S, Möllmert S, Möckel C, Choudhury S, Höpfel AI, Zorn T, Endres S, Schlauersbach J, Scheller L, Keßler C, Scherf-Clavel O, Bellstedt P, Schubert US, Pöppler AC, Heinze KG, Guck J, Meinel L. Bile Is a Selective Elevator for Mucosal Mechanics and Transport. Mol Pharm 2023; 20:6151-6161. [PMID: 37906224 DOI: 10.1021/acs.molpharmaceut.3c00550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Mucus mechanically protects the intestinal epithelium and impacts the absorption of drugs, with a largely unknown role for bile. We explored the impacts of bile on mucosal biomechanics and drug transport within mucus. Bile diffused with square-root-of-time kinetics and interplayed with mucus, leading to transient stiffening captured in Brillouin images and a concentration-dependent change from subdiffusive to Brownian-like diffusion kinetics within the mucus demonstrated by differential dynamic microscopy. Bile-interacting drugs, Fluphenazine and Perphenazine, diffused faster through mucus in the presence of bile, while Metoprolol, a drug with no bile interaction, displayed consistent diffusion. Our findings were corroborated by rat studies, where co-dosing of a bile acid sequestrant substantially reduced the bioavailability of Perphenazine but not Metoprolol. We clustered over 50 drugs based on their interactions with bile and mucin. Drugs that interacted with bile also interacted with mucin but not vice versa. This study detailed the dynamics of mucus biomechanics under bile exposure and linked the ability of a drug to interact with bile to its abbility to interact with mucus.
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Affiliation(s)
- Simon Hanio
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Stephanie Möllmert
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudtstrasse 2, 91058 Erlangen, Germany
| | - Conrad Möckel
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudtstrasse 2, 91058 Erlangen, Germany
| | - Susobhan Choudhury
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany
| | - Andreas I Höpfel
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany
| | - Theresa Zorn
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Sebastian Endres
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Jonas Schlauersbach
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Lena Scheller
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Christoph Keßler
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Oliver Scherf-Clavel
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Peter Bellstedt
- Institute of Organic Chemistry, University of Jena, Humboldtstrasse 10, 07743 Jena, Germany
- Institute for Clinical Chemistry, University of Zürich,Rämistrasse 100, 8091 Zurich, Switzerland
| | - Ulrich S Schubert
- Institute of Organic Chemistry, University of Jena, Humboldtstrasse 10, 07743 Jena, Germany
- Jena Center for Soft Matter (JCSM), University of Jena, Philosophenweg 7, 07743 Jena, Germany
| | - Ann-Christin Pöppler
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Katrin G Heinze
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany
| | - Jochen Guck
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudtstrasse 2, 91058 Erlangen, Germany
| | - Lorenz Meinel
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Josef-Schneider-Strasse 2, 97080 Wuerzburg, Germany
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Desoutter A, Felbacq D, Gergely C, Varga B, Bonnet L, Etienne P, Vialla R, Cuisinier F, Salehi H, Rousseau E, Rufflé B. Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy. Arch Oral Biol 2023; 152:105733. [PMID: 37247560 DOI: 10.1016/j.archoralbio.2023.105733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 05/31/2023]
Abstract
OBJECTIVE Dentin, enamel and the transition zone, called the dentin-enamel junction (DEJ), have an organization and properties that play a critical role in tooth resilience and in stopping the propagation of cracks. Understanding their chemical and micro-biomechanical properties is then of foremost importance. The aim of this study is to apply Brillouin microscopy on a complex biological structure, that is, the DEJ, and to compare these results with those obtained with Raman microscopy. DESIGN Both techniques allow noncontact measurements at the microscopic scale. Brillouin microscopy is based on the interaction between acoustic phonons and laser photons and gives a relation between the frequency shift of the scattered light and the stiffness of the sample. Raman spectra contain peaks related to specific chemical bonds. RESULTS Comparison of the Brillouin and Raman cartographies reveals correlations between mechanical and chemical properties. Indeed, the shapes of the phosphate content and stiffness curves are similar. The two spectroscopies give compatible values for the mean distance between two tubules, i.e., 4-6 µm. Moreover, for the first time, the daily cross striations of enamel could be studied, indicating a relationship between the variation in the phosphate concentration and the variation in the rigidity within the enamel prisms. CONCLUSIONS We demonstrate here the possibility of using Brillouin scattering microscopy to both study complex biological materials such as the enamel-dentin junction and visualize secondary structures. Correlations between the chemical composition and mechanical properties could help in better understanding the tissue histology.
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Affiliation(s)
- Alban Desoutter
- LBN, Univ. Montpellier, 545 avenue Professeur Jean-Louis Viala, 34193 Montpellier Cedex 5, France.
| | - Didier Felbacq
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Csilla Gergely
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Béla Varga
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Laurent Bonnet
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Pascal Etienne
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Remy Vialla
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Frédéric Cuisinier
- LBN, Univ. Montpellier, 545 avenue Professeur Jean-Louis Viala, 34193 Montpellier Cedex 5, France
| | - Hamideh Salehi
- LBN, Univ. Montpellier, 545 avenue Professeur Jean-Louis Viala, 34193 Montpellier Cedex 5, France
| | - Emmanuel Rousseau
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
| | - Benoit Rufflé
- L2C, Univ. Montpellier, CNRS, place Eugène Bataillon, 34090 Montpellier, France
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Lan G, Twa MD, Song C, Feng J, Huang Y, Xu J, Qin J, An L, Wei X. In vivo corneal elastography: A topical review of challenges and opportunities. Comput Struct Biotechnol J 2023; 21:2664-2687. [PMID: 37181662 PMCID: PMC10173410 DOI: 10.1016/j.csbj.2023.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023] Open
Abstract
Clinical measurement of corneal biomechanics can aid in the early diagnosis, progression tracking, and treatment evaluation of ocular diseases. Over the past two decades, interdisciplinary collaborations between investigators in optical engineering, analytical biomechanical modeling, and clinical research has expanded our knowledge of corneal biomechanics. These advances have led to innovations in testing methods (ex vivo, and recently, in vivo) across multiple spatial and strain scales. However, in vivo measurement of corneal biomechanics remains a long-standing challenge and is currently an active area of research. Here, we review the existing and emerging approaches for in vivo corneal biomechanics evaluation, which include corneal applanation methods, such as ocular response analyzer (ORA) and corneal visualization Scheimpflug technology (Corvis ST), Brillouin microscopy, and elastography methods, and the emerging field of optical coherence elastography (OCE). We describe the fundamental concepts, analytical methods, and current clinical status for each of these methods. Finally, we discuss open questions for the current state of in vivo biomechanics assessment techniques and requirements for wider use that will further broaden our understanding of corneal biomechanics for the detection and management of ocular diseases, and improve the safety and efficacy of future clinical practice.
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Affiliation(s)
- Gongpu Lan
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Michael D Twa
- College of Optometry, University of Houston, Houston, TX 77204, United States
| | - Chengjin Song
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
| | - JinPing Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Yanping Huang
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jingjiang Xu
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jia Qin
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Lin An
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Xunbin Wei
- Biomedical Engineering Department, Peking University, Beijing 100081, China
- International Cancer Institute, Peking University, Beijing 100191, China
- Institute of Medical Technology, Peking University Health Science Center, Beijing 100191, China
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Shi C, Zhang H, Zhang J. Non-contact and label-free biomechanical imaging: Stimulated Brillouin microscopy and beyond. Front Phys 2023; 11:1175653. [PMID: 37377499 PMCID: PMC10299794 DOI: 10.3389/fphy.2023.1175653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Brillouin microscopy based on spontaneous Brillouin scattering has emerged as a unique elastography technique because of its merit of non-contact, label-free, and high-resolution mechanical imaging of biological cell and tissue. Recently, several new optical modalities based on stimulated Brillouin scattering have been developed for biomechanical research. As the scattering efficiency of the stimulated process is much higher than its counterpart in the spontaneous process, stimulated Brillouin-based methods have the potential to significantly improve the speed and spectral resolution of existing Brillouin microscopy. Here, we review the ongoing technological advancements of three methods, including continuous wave stimulated Brillouin microscopy, impulsive stimulated Brillouin microscopy, and laser-induced picosecond ultrasonics. We describe the physical principle, the representative instrumentation, and biological application of each method. We further discuss the current limitations as well as the challenges for translating these methods into a visible biomedical instrument for biophysics and mechanobiology.
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Affiliation(s)
- Chenjun Shi
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States
| | - Hongyuan Zhang
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Jitao Zhang
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States
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6
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Ishijima A, Okabe S, Sakuma I, Nakagawa K. Dispersive coherent Brillouin scattering spectroscopy. Photoacoustics 2023; 29:100447. [PMID: 36601363 PMCID: PMC9806682 DOI: 10.1016/j.pacs.2022.100447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 12/24/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
Frequency- and time-domain Brillouin scattering spectroscopy are powerful tools to read out the mechanical properties of complex systems in material and life sciences. Indeed, coherent acoustic phonons in the time-domain method offer superior depth resolution and a stronger signal than incoherent acoustic phonons in the frequency-domain method. However, it requires scanning of delay time between laser pulses for pumping and probing coherent acoustic phonons. Here, we present Brillouin scattering spectroscopy that spans the time and frequency domains to allow the multichannel detection of Brillouin scattering light from coherent acoustic phonons. Our technique traces the time-evolve Brillouin oscillations at the instantaneous frequency of a chromatic-dispersed laser pulse. The spectroscopic heterodyning of Brillouin scattering light in the frequency domain allows a single-frame readout of gigahertz-frequency oscillations with a spectrometer. As a proof of concept, we imaged heterogeneous thin films and biological cells over a wide bandwidth with nanometer depth resolution.
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Affiliation(s)
- Ayumu Ishijima
- Department of Precision Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Shinga Okabe
- Department of Bioengineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Ichiro Sakuma
- Department of Precision Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Department of Bioengineering, The University of Tokyo, Tokyo 113-8656, Japan
- Medical Device Development and Regulation Research Center, The University of Tokyo, Tokyo 113-8656, Japan
| | - Keiichi Nakagawa
- Department of Precision Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Department of Bioengineering, The University of Tokyo, Tokyo 113-8656, Japan
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7
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Schlüßler R, Kim K, Nötzel M, Taubenberger A, Abuhattum S, Beck T, Müller P, Maharana S, Cojoc G, Girardo S, Hermann A, Alberti S, Guck J. Correlative all-optical quantification of mass density and mechanics of subcellular compartments with fluorescence specificity. eLife 2022; 11:e68490. [PMID: 35001870 PMCID: PMC8816383 DOI: 10.7554/elife.68490] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 01/08/2022] [Indexed: 01/06/2023] Open
Abstract
Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples - so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epifluorescence imaging for explicitly measuring the Brillouin shift, RI, and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample - a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.
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Affiliation(s)
- Raimund Schlüßler
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Kyoohyun Kim
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Martin Nötzel
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Anna Taubenberger
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Shada Abuhattum
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Timon Beck
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Paul Müller
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Shovamaye Maharana
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBengaluruIndia
| | - Gheorghe Cojoc
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Salvatore Girardo
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Andreas Hermann
- Translational Neurodegeneration Section "Albrecht Kossel", University Rostock, and German Center for Neurodegenerative Diseases (DZNE)Rostock/GreifswaldGermany
| | - Simon Alberti
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Physics of Life, Technische Universität DresdenDresdenGermany
| | - Jochen Guck
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
- Physics of Life, Technische Universität DresdenDresdenGermany
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Mahajan V, Beck T, Gregorczyk P, Ruland A, Alberti S, Guck J, Werner C, Schlüßler R, Taubenberger AV. Mapping Tumor Spheroid Mechanics in Dependence of 3D Microenvironment Stiffness and Degradability by Brillouin Microscopy. Cancers (Basel) 2021; 13:5549. [PMID: 34771711 PMCID: PMC8583550 DOI: 10.3390/cancers13215549] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 12/14/2022] Open
Abstract
Altered biophysical properties of cancer cells and of their microenvironment contribute to cancer progression. While the relationship between microenvironmental stiffness and cancer cell mechanical properties and responses has been previously studied using two-dimensional (2D) systems, much less is known about it in a physiologically more relevant 3D context and in particular for multicellular systems. To investigate the influence of microenvironment stiffness on tumor spheroid mechanics, we first generated MCF-7 tumor spheroids within matrix metalloproteinase (MMP)-degradable 3D polyethylene glycol (PEG)-heparin hydrogels, where spheroids showed reduced growth in stiffer hydrogels. We then quantitatively mapped the mechanical properties of tumor spheroids in situ using Brillouin microscopy. Maps acquired for tumor spheroids grown within stiff hydrogels showed elevated Brillouin frequency shifts (hence increased longitudinal elastic moduli) with increasing hydrogel stiffness. Maps furthermore revealed spatial variations of the mechanical properties across the spheroids' cross-sections. When hydrogel degradability was blocked, comparable Brillouin frequency shifts of the MCF-7 spheroids were found in both compliant and stiff hydrogels, along with similar levels of growth-induced compressive stress. Under low compressive stress, single cells or free multicellular aggregates showed consistently lower Brillouin frequency shifts compared to spheroids growing within hydrogels. Thus, the spheroids' mechanical properties were modulated by matrix stiffness and degradability as well as multicellularity, and also to the associated level of compressive stress felt by tumor spheroids. Spheroids generated from a panel of invasive breast, prostate and pancreatic cancer cell lines within degradable stiff hydrogels, showed higher Brillouin frequency shifts and less cell invasion compared to those in compliant hydrogels. Taken together, our findings contribute to a better understanding of the interplay between cancer cells and microenvironment mechanics and degradability, which is relevant to better understand cancer progression.
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Affiliation(s)
- Vaibhav Mahajan
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
| | - Timon Beck
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Staudtstr. 2, 91058 Erlangen, Germany;
| | - Paulina Gregorczyk
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
| | - André Ruland
- Max Bergmann Center, Leibniz Institute of Polymer Research Dresden, 01069 Dresden, Germany; (A.R.); (C.W.)
| | - Simon Alberti
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
| | - Jochen Guck
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Staudtstr. 2, 91058 Erlangen, Germany;
| | - Carsten Werner
- Max Bergmann Center, Leibniz Institute of Polymer Research Dresden, 01069 Dresden, Germany; (A.R.); (C.W.)
| | - Raimund Schlüßler
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
| | - Anna Verena Taubenberger
- Center for Molecular and Cellular Bioengineering (CMCB), BIOTEC, Technische Universitaet Dresden, 01307 Dresden, Germany; (V.M.); (T.B.); (P.G.); (S.A.); (R.S.)
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Roberts AB, Zhang J, Raj Singh V, Nikolić M, Moeendarbary E, Kamm RD, So PTC, Scarcelli G. Tumor cell nuclei soften during transendothelial migration. J Biomech 2021; 121:110400. [PMID: 33882444 PMCID: PMC8274349 DOI: 10.1016/j.jbiomech.2021.110400] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 02/08/2023]
Abstract
During cancer metastasis, tumor cells undergo significant deformation in order to traverse through endothelial cell junctions in the walls of blood vessels. As cells pass through narrow gaps, smaller than the nuclear diameter, the spatial configuration of chromatin must change along with the distribution of nuclear enzymes. Nuclear stiffness is an important determinant of the ability of cells to undergo transendothelial migration, yet no studies have been conducted to assess whether tumor cell cytoskeletal or nuclear stiffness changes during this critical process in order to facilitate passage. To address this question, we employed two non-contact methods, Brillouin confocal microscopy (BCM) and confocal reflectance quantitative phase microscopy (QPM), to track the changes in mechanical properties of live, transmigrating tumor cells in an in vitro collagen gel platform. Using these two imaging modalities to study transmigrating MDA-MB-231, A549, and A375 cells, we found that both the cells and their nuclei soften upon extravasation and that the nuclear membranes remain soft for at least 24 h. These new data suggest that tumor cells adjust their mechanical properties in order to facilitate extravasation.
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Affiliation(s)
- Anya B Roberts
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA
| | - Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park 20742, MD, USA
| | - Vijay Raj Singh
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA; Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge 02139, MA, USA
| | - Miloš Nikolić
- Maryland Biophysics Program, University of Maryland, College Park, MD 20742, USA
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Roger D Kamm
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA.
| | - Peter T C So
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, MA, USA; Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge 02139, MA, USA.
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park 20742, MD, USA; Maryland Biophysics Program, University of Maryland, College Park, MD 20742, USA.
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10
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Bailey M, Gardner B, Alunni-Cardinali M, Caponi S, Fioretto D, Stone N, Palombo F. Predicting the Refractive Index of Tissue Models Using Light Scattering Spectroscopy. Appl Spectrosc 2021; 75:574-580. [PMID: 33319606 PMCID: PMC8114435 DOI: 10.1177/0003702820984482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
In this work, we report the application of Raman microspectroscopy for analysis of the refractive index of a range of tissue phantoms. Using both a custom-developed setup with visible laser source and a commercial microspectrometer with near infrared laser, we measured the Raman spectra of gelatin hydrogels at various concentrations. By building a calibration curve from measured refractometry data and Raman scattering intensity for different vibrational modes of the hydrogel, we were able to predict the refractive indices of the gels from their Raman spectra. This work highlights the importance of a correlative approach through Brillouin-Raman microspectroscopy for the mechano-chemical analysis of biologically relevant samples.
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Affiliation(s)
- Michelle Bailey
- School of Physics and Astronomy, University of Exeter, Exeter, UK
| | - Benjamin Gardner
- School of Physics and Astronomy, University of Exeter, Exeter, UK
| | | | - Silvia Caponi
- CNR-IOM – Istituto Officina dei Materiali – Research Unit in Perugia, c/o Department of Physics and Geology, University of Perugia, Perugia, Italy
| | - Daniele Fioretto
- Department of Physics and Geology, University of Perugia, Perugia, Italy
| | - Nick Stone
- School of Physics and Astronomy, University of Exeter, Exeter, UK
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11
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Chong J, Dupps WJ. Corneal biomechanics: Measurement and structural correlations. Exp Eye Res 2021; 205:108508. [PMID: 33609511 DOI: 10.1016/j.exer.2021.108508] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/09/2021] [Accepted: 02/12/2021] [Indexed: 02/02/2023]
Abstract
The characterization of corneal biomechanical properties has important implications for the management of ocular disease and prediction of surgical responses. Corneal refractive surgery outcomes, progression or stabilization of ectatic disease, and intraocular pressure determination are just examples of the many key clinical problems that depend highly upon corneal biomechanical characteristics. However, to date there is no gold standard measurement technique. Since the advent of a 1-dimensional (1D) air-puff based technique for measuring the corneal surface response in 2005, advances in clinical imaging technology have yielded increasingly sophisticated approaches to characterizing the biomechanical properties of the cornea. Novel analyses of 1D responses are expanding the clinical utility of commercially-available air-puff-based instruments, and other imaging modalities-including optical coherence elastography (OCE), Brillouin microscopy and phase-decorrelation ocular coherence tomography (PhD-OCT)-offer new opportunities for probing local biomechanical behavior in 3-dimensional space and drawing new inferences about the relationships between corneal structure, mechanical behavior, and corneal refractive function. These advances are likely to drive greater clinical adoption of in vivo biomechanical analysis and to support more personalized medical and surgical decision-making.
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Affiliation(s)
- Jillian Chong
- Cleveland Clinic Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - William J Dupps
- Cleveland Clinic Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA; Dept. of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve Univ, Cleveland, OH, USA; Dept. of Biomedical Engineering, Lerner Research Institute and Case Western Reserve Univ, Cleveland, OH, USA.
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12
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Narasimhan BN, Ting MS, Kollmetz T, Horrocks MS, Chalard AE, Malmström J. Mechanical Characterization for Cellular Mechanobiology: Current Trends and Future Prospects. Front Bioeng Biotechnol 2020; 8:595978. [PMID: 33282852 PMCID: PMC7689259 DOI: 10.3389/fbioe.2020.595978] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/27/2020] [Indexed: 11/13/2022] Open
Abstract
Accurate mechanical characterization of adherent cells and their substrates is important for understanding the influence of mechanical properties on cells themselves. Recent mechanobiology studies outline the importance of mechanical parameters, such as stress relaxation and strain stiffening on the behavior of cells. Numerous techniques exist for probing mechanical properties and it is vital to understand the benefits of each technique and how they relate to each other. This mini review aims to guide the reader through the toolbox of mechanical characterization techniques by presenting well-established and emerging methods currently used to assess mechanical properties of substrates and cells.
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Affiliation(s)
- Badri Narayanan Narasimhan
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Matthew S. Ting
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Tarek Kollmetz
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Matthew S. Horrocks
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Anaïs E. Chalard
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Jenny Malmström
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
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13
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Ambekar YS, Singh M, Scarcelli G, Rueda EM, Hall BM, Poché RA, Larin KV. Characterization of retinal biomechanical properties using Brillouin microscopy. J Biomed Opt 2020; 25:JBO-200208LR. [PMID: 32981240 PMCID: PMC7519206 DOI: 10.1117/1.jbo.25.9.090502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/04/2020] [Indexed: 05/03/2023]
Abstract
SIGNIFICANCE The retina is critical for vision, and several diseases may alter its biomechanical properties. However, assessing the biomechanical properties of the retina nondestructively is a challenge due to its fragile nature and location within the eye globe. Advancements in Brillouin spectroscopy have provided the means for nondestructive investigations of retina biomechanical properties. AIM We assessed the biomechanical properties of mouse retinas using Brillouin microscopy noninvasively and showed the potential of Brillouin microscopy to differentiate the type and layers of retinas based on stiffness. APPROACH We used Brillouin microscopy to quantify stiffness of fresh and paraformaldehyde (PFA)-fixed retinas. As further proof-of-concept, we demonstrated a change in the stiffness of a retina with N-methyl-D-aspartate (NMDA)-induced damage, compared to an undamaged sample. RESULTS We found that the retina layers with higher cell body density had higher Brillouin modulus compared to less cell-dense layers. We have also demonstrated that PFA-fixed retina samples were stiffer compared with fresh samples. Further, NMDA-induced neurotoxicity leads to retinal ganglion cell (RGC) death and reactive gliosis, increasing the stiffness of the RGC layer. CONCLUSION Brillouin microscopy can be used to characterize the stiffness distribution of the layers of the retina and can be used to differentiate tissue at different conditions based on biomechanical properties.
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Affiliation(s)
- Yogeshwari S. Ambekar
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Giuliano Scarcelli
- University of Maryland, Fischell Department of Bioengineering, College Park, Maryland, United States
| | - Elda M. Rueda
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas, United States
| | - Benjamin M. Hall
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas, United States
| | - Ross A. Poché
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas, United States
- Address all correspondence to Ross A. Poché, E-mail: ; Kirill V. Larin, E-mail:
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas, United States
- Address all correspondence to Ross A. Poché, E-mail: ; Kirill V. Larin, E-mail:
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14
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Webb JN, Zhang H, Sinha Roy A, Randleman JB, Scarcelli G. Detecting Mechanical Anisotropy of the Cornea Using Brillouin Microscopy. Transl Vis Sci Technol 2020; 9:26. [PMID: 32832232 PMCID: PMC7414627 DOI: 10.1167/tvst.9.7.26] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/28/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose The purpose of this study was to detect the mechanical anisotropy of the cornea using Brillouin microscopy along different perturbation directions. Methods Brillouin frequency shift of both whole globes (n = 10) and cornea punches (n = 10) were measured at different angles to the incident laser, thereby probing corneal longitudinal modulus of elasticity along different directions. Frequency shift of virgin (n = 26) versus cross-linked corneas (n = 15) over a large range of hydration conditions were compared in order to differentiate the contributions to Brillouin shift due to hydration from those due to stromal tissue. Results We detected mechanical anisotropy of corneas, with an average frequency shift increase of 53 MHz and 96 MHz when the instrument probed from 0° to 15° and 30° along the direction of the stromal fibers. Brillouin microscopy did not lose sensitivity to mechanical anisotropy up to 96% water content. We experimentally measured and theoretically modeled how mechanical changes independent of hydration affect frequency shift as a result of corneal cross-linking by isolating an approximately 100 MHz increase in frequency shift following a cross-linking procedure purely due to changes of stromal tissue mechanics. Conclusions Brillouin microscopy is sensitive to mechanical anisotropy of the stroma even in highly hydrated corneas. The agreement between model and experimental data suggested a quantitative relationship between Brillouin frequency shift, hydration state of the cornea, and stromal tissue stiffness. Translational Relevance The protocol and model validated throughout this study offer a path for comprehensive measurements of corneal mechanics within the clinic; allowing for improved evaluation of the long-term mechanical efficacy of cross-linking procedures.
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Affiliation(s)
- Joshua N Webb
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
| | - Hongyuan Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.,Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | | | | | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
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15
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Antonacci G, Beck T, Bilenca A, Czarske J, Elsayad K, Guck J, Kim K, Krug B, Palombo F, Prevedel R, Scarcelli G. Recent progress and current opinions in Brillouin microscopy for life science applications. Biophys Rev 2020; 12:615-624. [PMID: 32458371 PMCID: PMC7311586 DOI: 10.1007/s12551-020-00701-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 05/07/2020] [Indexed: 12/20/2022] Open
Abstract
Many important biological functions and processes are reflected in cell and tissue mechanical properties such as elasticity and viscosity. However, current techniques used for measuring these properties have major limitations, such as that they can often not measure inside intact cells and/or require physical contact-which cells can react to and change. Brillouin light scattering offers the ability to measure mechanical properties in a non-contact and label-free manner inside of objects with high spatial resolution using light, and hence has emerged as an attractive method during the past decade. This new approach, coined "Brillouin microscopy," which integrates highly interdisciplinary concepts from physics, engineering, and mechanobiology, has led to a vibrant new community that has organized itself via a European funded (COST Action) network. Here we share our current assessment and opinion of the field, as emerged from a recent dedicated workshop. In particular, we discuss the prospects towards improved and more bio-compatible instrumentation, novel strategies to infer more accurate and quantitative mechanical measurements, as well as our current view on the biomechanical interpretation of the Brillouin spectra.
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Affiliation(s)
- Giuseppe Antonacci
- Photonics Research Group, INTEC, Ghent University-imec, 9052, Ghent, Belgium
- Present address: Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milan, Italy
| | - Timon Beck
- Biotechnology Center, TU Dresden, Dresden, Germany
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Alberto Bilenca
- Biomedical Engineering Department, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Jürgen Czarske
- Laboratory of Measurement and Sensor System Technique, TU Dresden, Dresden, Germany
- Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany
| | - Kareem Elsayad
- Advanced Microscopy, Vienna Biocenter Core Facilities (VBCF), Vienna, Austria.
| | - Jochen Guck
- Biotechnology Center, TU Dresden, Dresden, Germany
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Kyoohyun Kim
- Biotechnology Center, TU Dresden, Dresden, Germany
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Benedikt Krug
- Laboratory of Measurement and Sensor System Technique, TU Dresden, Dresden, Germany
| | | | - Robert Prevedel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
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16
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Zhang J, Alisafaei F, Nikolić M, Nou XA, Kim H, Shenoy VB, Scarcelli G. Nuclear Mechanics within Intact Cells Is Regulated by Cytoskeletal Network and Internal Nanostructures. Small 2020; 16:e1907688. [PMID: 32243075 PMCID: PMC7799396 DOI: 10.1002/smll.201907688] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 05/11/2023]
Abstract
The mechanical properties of the cellular nucleus are extensively studied as they play a critical role in important processes, such as cell migration, gene transcription, and stem cell differentiation. While the mechanical properties of the isolated nucleus have been tested, there is a lack of measurements about the mechanical behavior of the nucleus within intact cells and specifically about the interplay of internal nuclear components with the intracellular microenvironment, because current testing methods are based on contact and only allow studying the nucleus after isolation from a cell or disruption of cytoskeleton. Here, all-optical Brillouin microscopy and 3D chemomechanical modeling are used to investigate the regulation of nuclear mechanics in physiological conditions. It is observed that the nuclear modulus can be modulated by epigenetic regulation targeting internal nuclear nanostructures such as lamin A/C and chromatin. It is also found that nuclear modulus is strongly regulated by cytoskeletal behavior through a robust mechanism conserved in different culturing conditions. Given the active role of cytoskeletal modulation in nearly all cell functions, this work will enable to reveal highly relevant mechanisms of nuclear mechanical regulations in physiological and pathological conditions.
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Affiliation(s)
- Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Farid Alisafaei
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, PA, 19104, USA
- Center for Engineering Mechanobiology, University of Pennsylvania, PA, 19104, USA
| | - Miloš Nikolić
- Maryland Biophysics Program, University of Maryland, College Park, MD 20742, USA
| | - Xuefei A. Nou
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Hanyoup Kim
- Canon U.S. Life Sciences, Inc., 9800 Medical Center Drive, Suite C-120, Rockville, MD 20850, USA
| | - Vivek B. Shenoy
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, PA, 19104, USA
- Center for Engineering Mechanobiology, University of Pennsylvania, PA, 19104, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
- Maryland Biophysics Program, University of Maryland, College Park, MD 20742, USA
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17
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Sánchez-Iranzo H, Bevilacqua C, Diz-Muñoz A, Prevedel R. A 3D Brillouin microscopy dataset of the in-vivo zebrafish eye. Data Brief 2020; 30:105427. [PMID: 32274409 PMCID: PMC7132165 DOI: 10.1016/j.dib.2020.105427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 11/30/2022] Open
Abstract
In this work we present three-dimensional (3D) measurements of Brillouin scattering spectra of the in-vivo zebrafish larvae eye. This dataset was obtained by Brillouin microscopy, an emerging all-optical and non-contact technique that gives access to material properties through the process of Brillouin scattering. Herein, we share a representative 3D dataset of spectral properties of 48–52 h post-fertilization (hpf) zebrafish embryos. These spectral properties can be related to a complex longitudinal modulus and thus elastic and viscous properties given knowledge of refractive index and material density. The dataset encompasses the crystalline lens as well as several different retinal layers. This data provides a valuable resource as well as a starting point for researchers interested in the mechanobiology of vertebrate eye development.
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Affiliation(s)
- Héctor Sánchez-Iranzo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carlo Bevilacqua
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Alba Diz-Muñoz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Robert Prevedel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Monterotondo, Italy.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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18
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Lainović T, Margueritat J, Martinet Q, Dagany X, Blažić L, Pantelić D, Rabasović MD, Krmpot AJ, Dehoux T. Micromechanical imaging of dentin with Brillouin microscopy. Acta Biomater 2020; 105:214-222. [PMID: 31988041 DOI: 10.1016/j.actbio.2020.01.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 01/10/2023]
Abstract
The structure of teeth can be altered by diet, age or diseases such as caries and sclerosis. It is very important to characterize their mechanical properties to predict and understand tooth decay, design restorative dental procedures, and investigate their tribological behavior. However, existing imaging techniques are not well suited to investigating the micromechanics of teeth, in particular at tissue interfaces. Here, we describe a microscope based on Brillouin light scattering (BLS) developed to probe the spectrum of the light scattered from tooth tissues, from which the mechanical properties (sound velocity, viscosity) can be inferred with a priori knowledge of the refractive index. BLS is an inelastic process that uses the scattering of light by acoustic waves in the GHz range. Our microscope thus reveals the mechanical properties at the micrometer scale without contact with the sample. BLS signals show significant differences between sound tissues and pathological lesions, and can be used to precisely delineate carious dentin. We also show maps of the sagittal and transversal planes of sound tubular dentin that reveal its anisotropic microstructure at 1 µm resolution. Our observations indicate that the collagen-based matrix of dentine is the main load-bearing structure, which can be considered as a fiber-reinforced composite. In the vicinity of polymeric tooth-filling materials, we observed the infiltration of the adhesive complex into the opened tubules of sound dentine. The ability to probe the quality of this interfacial layer could lead to innovative designs of biomaterials used for dental restorations in contemporary adhesive dentistry, with possible direct repercussions on decision-making during clinical work. STATEMENT OF SIGNIFICANCE: Mechanical properties of teeth can be altered by diet, age or diseases. Yet existing imaging modalities cannot reveal the micromechanics of the tooth. Here we developed a new type of microscope that uses the scattering of a laser light by naturally-occurring acoustic waves to probe mechanical changes in tooth tissues at a sub-micrometer scale without contact to the sample. We observe significant mechanical differences between healthy tissues and pathological lesions. The contrast in mechanical properties also reveals the microstructure of the polymer-dentin interfaces. We believe that this new development of laser spectroscopy is very important because it should lead to innovative designs of biomaterials used for dental restoration, and allow delineating precisely destructed dentin for minimally-invasive strategies.
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19
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Nötzel M, Rosso G, Möllmert S, Seifert A, Schlüßler R, Kim K, Hermann A, Guck J. Axonal Transport, Phase-Separated Compartments, and Neuron Mechanics - A New Approach to Investigate Neurodegenerative Diseases. Front Cell Neurosci 2018; 12:358. [PMID: 30356682 PMCID: PMC6189317 DOI: 10.3389/fncel.2018.00358] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/24/2018] [Indexed: 01/07/2023] Open
Abstract
Many molecular and cellular pathogenic mechanisms of neurodegenerative diseases have been revealed. However, it is unclear what role a putatively impaired neuronal transport with respect to altered mechanical properties of neurons play in the initiation and progression of such diseases. The biochemical aspects of intracellular axonal transport, which is important for molecular movements through the cytoplasm, e.g., mitochondrial movement, has already been studied. Interestingly, transport deficiencies are associated with the emergence of the affliction and potentially linked to disease transmission. Transport along the axon depends on the normal function of the neuronal cytoskeleton, which is also a major contributor to neuronal mechanical properties. By contrast, little attention has been paid to the mechanical properties of neurons and axons impaired by neurodegeneration, and of membraneless, phase-separated organelles such as stress granules (SGs) within neurons. Mechanical changes may indicate cytoskeleton reorganization and function, and thus give information about the transport and other system impairment. Nowadays, several techniques to investigate cellular mechanical properties are available. In this review, we discuss how select biophysical methods to probe material properties could contribute to the general understanding of mechanisms underlying neurodegenerative diseases.
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Affiliation(s)
- Martin Nötzel
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
| | - Gonzalo Rosso
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
| | - Stephanie Möllmert
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
| | - Anne Seifert
- Department of Neurology, Technische Universität Dresden, Dresden, Germany
- Center for Regenerative Therapies (CRTD), Technische Universität Dresden, Dresden, Germany
- German Center for Neurodegenerative Diseases, Dresden, Germany
| | - Raimund Schlüßler
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
| | - Kyoohyun Kim
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
| | - Andreas Hermann
- Department of Neurology, Technische Universität Dresden, Dresden, Germany
- Center for Regenerative Therapies (CRTD), Technische Universität Dresden, Dresden, Germany
- German Center for Neurodegenerative Diseases, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Dresden University of Technology, Dresden, Germany
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20
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Zhang J, Raghunathan R, Rippy J, Wu C, Finnell RH, Larin KV, Scarcelli G. Tissue biomechanics during cranial neural tube closure measured by Brillouin microscopy and optical coherence tomography. Birth Defects Res 2018; 111:991-998. [PMID: 30239173 DOI: 10.1002/bdr2.1389] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/03/2018] [Accepted: 08/02/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Embryonic development involves the interplay of driving forces that shape the tissue and the mechanical resistance that the tissue offers in response. While increasing evidence has suggested the crucial role of physical mechanisms underlying embryo development, tissue biomechanics is not well understood because of the lack of techniques that can quantify the stiffness of tissue in situ with 3D high-resolution and in a noncontact manner. METHODS We used two all-optical techniques, optical coherence tomography (OCT) and Brillouin microscopy, to map the longitudinal modulus of the tissue from mouse embryos in situ. RESULTS We acquired 2D mechanical maps of the neural tube region of embryos at embryonic day (E) 8.5 (n = 2) and E9.5 (n = 2) with submicron spatial resolution. We found the modulus of tissue varied distinctly within the neural tube region of the same embryo and between embryos at different development stages, suggesting our technique has enough sensitivity and spatial resolution to monitor the tissue mechanics during embryonic development in a noncontact and noninvasive manner. CONCLUSIONS We demonstrated the capability of OCT-guided Brillouin microscopy to quantify tissue longitudinal modulus of mouse embryos in situ, and observed distinct change in the modulus during the closure of cranial neural tube. Although this preliminary work cannot provide definitive conclusions on biomechanics of neural tube closure yet as a result of the limited number of samples, it provides an approach of quantifying the tissue mechanics during embryo development in situ, thus could be helpful in investigating the role of tissue biomechanics in the regulation of embryonic development. Our next study involving more embryo samples will investigate systematic changes in tissue mechanics during embryonic development.
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Affiliation(s)
- Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland, Maryland
| | - Raksha Raghunathan
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Justin Rippy
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Chen Wu
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Richard H Finnell
- Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas.,Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas.,Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia
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Figueiredo GS, Bojic S, Rooney P, Wilshaw SP, Connon CJ, Gouveia RM, Paterson C, Lepert G, Mudhar HS, Figueiredo FC, Lako M. Gamma-irradiated human amniotic membrane decellularised with sodium dodecyl sulfate is a more efficient substrate for the ex vivo expansion of limbal stem cells. Acta Biomater 2017; 61:124-133. [PMID: 28760619 PMCID: PMC5598144 DOI: 10.1016/j.actbio.2017.07.041] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 11/25/2022]
Abstract
The gold standard substrate for the ex vivo expansion of human limbal stem cells (LSCs) remains the human amniotic membrane (HAM) but this is not a defined substrate and is subject to biological variability and the potential to transmit disease. To better define HAM and mitigate the risk of disease transmission, we sought to determine if decellularisation and/or γ-irradiation have an adverse effect on culture growth and LSC phenotype. Ex vivo limbal explant cultures were set up on fresh HAM, HAM decellularised with 0.5M NaOH, and 0.5% (w/v) sodium dodecyl sulfate (SDS) with or without γ-irradiation. Explant growth rate was measured and LSC phenotype was characterised by histology, immunostaining and qRT-PCR (ABCG2, ΔNp63, Ki67, CK12, and CK13). Ƴ-irradiation marginally stiffened HAM, as measured by Brillouin spectromicroscopy. HAM stiffness and γ-irradiation did not significantly affect the LSC phenotype, however LSCs expanded significantly faster on Ƴ-irradiated SDS decellularised HAM (p<0.05) which was also corroborated by the highest expression of Ki67 and putative LSC marker, ABCG2. Colony forming efficiency assays showed a greater yield and proportion of holoclones in cells cultured on Ƴ-irradiated SDS decellularised HAM. Together our data indicate that SDS decellularised HAM may be a more efficacious substrate for the expansion of LSCs and the use of a γ-irradiated HAM allows the user to start the manufacturing process with a sterile substrate, potentially making it safer. STATEMENT OF SIGNIFICANCE Despite its disadvantages, including its biological variability and its ability to transfer disease, human amniotic membrane (HAM) remains the gold standard substrate for limbal stem cell (LSC) culture. To address these disadvantages, we used a decellularised HAM sterilised by gamma-irradiation for LSC culture. We cultured LSCs on fresh HAM, HAM decellularised with NaOH, HAM decellularised with sodium dodecyl sulfate (SDS) and HAM decellularised with SDS and sterilised with gamma-irradiation. We demonstrated that although HAM decellularised with SDS and sterilised with gamma-irradiation is significantly stiffer this does not affect LSC culture growth rate or the phenotype of cultured LSCs. We therefore recommend the use of SDS decellularised gamma-irradiated HAM in future LSC clinical trials.
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Affiliation(s)
- G S Figueiredo
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK; Department of Ophthalmology, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK.
| | - S Bojic
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - P Rooney
- Tissue Services, NHS Blood and Transplant, 14 Estuary Banks, Speke, Liverpool L24 8RB, UK.
| | - S-P Wilshaw
- School of Pharmacy and Medical Sciences, Faculty of Life Sciences, University of Bradford, Bradford BD7 1DP, UK.
| | - C J Connon
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - R M Gouveia
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - C Paterson
- The Blackett Laboratory, South Kensington Campus, Imperial College, London SW7 2AZ, UK.
| | - G Lepert
- The Blackett Laboratory, South Kensington Campus, Imperial College, London SW7 2AZ, UK.
| | - H S Mudhar
- National Specialist Ophthalmic Pathology Service, Department of Histopathology, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, UK.
| | - F C Figueiredo
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK; Department of Ophthalmology, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK.
| | - M Lako
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
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Raghunathan R, Zhang J, Wu C, Rippy J, Singh M, Larin KV, Scarcelli G. Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography. J Biomed Opt 2017; 22:1-6. [PMID: 28861955 PMCID: PMC5582619 DOI: 10.1117/1.jbo.22.8.086013] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/03/2017] [Indexed: 05/19/2023]
Abstract
Embryogenesis is regulated by numerous changes in mechanical properties of the cellular microenvironment. Thus, studying embryonic mechanophysiology can provide a more thorough perspective of embryonic development, potentially improving early detection of congenital abnormalities as well as evaluating and developing therapeutic interventions. A number of methods and techniques have been used to study cellular biomechanical properties during embryogenesis. While some of these techniques are invasive or involve the use of external agents, others are compromised in terms of spatial and temporal resolutions. We propose the use of Brillouin microscopy in combination with optical coherence tomography (OCT) to measure stiffness as well as structural changes in a developing embryo. While Brillouin microscopy assesses the changes in stiffness among different organs of the embryo, OCT provides the necessary structural guidance.
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Affiliation(s)
- Raksha Raghunathan
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Jitao Zhang
- University of Maryland, Fischell Department of Bioengineering, College Park, Maryland, United States
| | - Chen Wu
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Justin Rippy
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
- Tomsk State University, Interdisciplinary Laboratory of Biophotonics, Tomsk, Russia
- Address all correspondence to: Kirill V. Larin, E-mail: ; Giuliano Scarcelli, E-mail:
| | - Giuliano Scarcelli
- University of Maryland, Fischell Department of Bioengineering, College Park, Maryland, United States
- Address all correspondence to: Kirill V. Larin, E-mail: ; Giuliano Scarcelli, E-mail:
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Girard MJA, Dupps WJ, Baskaran M, Scarcelli G, Yun SH, Quigley HA, Sigal IA, Strouthidis NG. Translating ocular biomechanics into clinical practice: current state and future prospects. Curr Eye Res 2015; 40:1-18. [PMID: 24832392 PMCID: PMC4233020 DOI: 10.3109/02713683.2014.914543] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.
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Affiliation(s)
- Michaël J A Girard
- In Vivo Biomechanics Laboratory, Department of Biomedical Engineering, National University of Singapore , Singapore
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Scarcelli G, Besner S, Pineda R, Yun SH. Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy. Invest Ophthalmol Vis Sci 2014; 55:4490-5. [PMID: 24938517 DOI: 10.1167/iovs.14-14450] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Loss of corneal strength is a central feature of keratoconus progression. However, it is currently difficult to measure corneal mechanical changes noninvasively. The objective of this study is to evaluate if Brillouin optical microscopy can differentiate the mechanical properties of keratoconic corneas versus healthy corneas ex vivo. METHODS We obtained eight tissue samples from healthy donor corneas used in Descemet's stripping endothelial keratoplasty (DSEK) and 10 advanced keratoconic corneas from patients undergoing deep anterior lamellar keratoplasty (DALK). Within 2 hours after surgery, a confocal Brillouin microscope using a monochromatic laser at 532 nm was used to map the Brillouin frequency shifts of the corneas. RESULTS The mean Brillouin shift in the anterior 200 μm of the keratoconic corneas at the cone was measured to be 7.99 ± 0.10 GHz, significantly lower than 8.17 ± 0.06 GHz of the healthy corneas (P < 0.001). The Brillouin shift in the keratoconic corneas decreased with depth from the anterior toward posterior regions with a steeper slope than in the healthy corneas (P < 0.001). Within keratoconic corneas, the Brillouin shift in regions away from the apex of the cone was significantly higher than within the cone region (P < 0.001). CONCLUSIONS Brillouin measurements revealed notable differences between healthy and keratoconic corneas. Importantly, Brillouin imaging showed that the mechanical loss is primarily concentrated within the area of the keratoconic cone. Outside the cone, the Brillouin shift was comparable with that of healthy corneas. The results demonstrate the potential of Brillouin microscopy for diagnosis and treatment monitoring of keratoconus.
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Affiliation(s)
- Giuliano Scarcelli
- Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States
| | - Sebastien Besner
- Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States
| | - Roberto Pineda
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
| | - Seok Hyun Yun
- Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States Harvard-MIT Health Sciences and Technology, Cambridge, Massachusetts, United States
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