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Vinciguerra R, Palladino S, Herber R, Romano MR, Vinciguerra P. The KERATO Biomechanics Study 1: A Comparative Evaluation Using Brillouin Microscopy and Dynamic Scheimpflug Imaging. J Refract Surg 2024; 40:e569-e578. [PMID: 39120013 DOI: 10.3928/1081597x-20240701-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
PURPOSE To assess the corneal biomechanical properties in normal individuals and patients with keratoconus using the Brillouin optical scanning system (Intelon Optics) (BOSS) and compare them with ultra-high-speed Scheimpflug imaging (Corvis ST; Oculus Optikgeräte GmbH). METHODS Sixty eyes from 60 patients (30 normal and 30 keratoconus) were included in this prospective, single-center, comparative, non-interventional study. Corneal biomechanics were evaluated using the Corvis ST and the BOSS. With the BOSS, each corneal image was acquired three times, measuring 10 locations within an 8-mm diameter. Parameters extracted included mean, maximum, and minimum Brillouin shift. These 10 points were also grouped into superior, central, and inferior regions. BOSS repeatability was assessed using the coefficient of repeatability and coefficient of variation. Furthermore, normal individuals and patients with keratoconus were compared using the Corvis ST and BOSS. RESULTS The BOSS exhibited good repeatability, with coefficient of repeatability ranging from 0.098 to 0.138 GHz for single points in normal individuals and 0.096 to 0.149 GHz for patients with keratoconus. Statistical analysis revealed significant differences between normal individuals and patients with keratoconus, indicating softer corneas in keratoconus, observed with both the Corvis ST and BOSS. Specifically, the BOSS showed significant differences in mean, inferior, and superior mean, maximum, and minimum Brillouin frequency shift (all P < .05), whereas the Corvis ST displayed highly significant differences in stiffness parameter at first applanation, stress strain index, deformation amplitude ratio, and inverse integrated radius (all P < .001). CONCLUSIONS Corneal biomechanical measurements proved highly repeatable and effectively demonstrated significant differences between normal individuals and patients with keratoconus using both the BOSS and the Corvis ST. [J Refract Surg. 2024;40(8):e569-e578.].
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Antonacci G, Vanna R, Ventura M, Schiavone ML, Sobacchi C, Behrouzitabar M, Polli D, Manzoni C, Cerullo G. Birefringence-induced phase delay enables Brillouin mechanical imaging in turbid media. Nat Commun 2024; 15:5202. [PMID: 38898004 PMCID: PMC11187154 DOI: 10.1038/s41467-024-49419-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 06/04/2024] [Indexed: 06/21/2024] Open
Abstract
Acoustic vibrations of matter convey fundamental viscoelastic information that can be optically retrieved by hyperfine spectral analysis of the inelastic Brillouin scattered light. Increasing evidence of the central role of the viscoelastic properties in biological processes has stimulated the rise of non-contact Brillouin microscopy, yet this method faces challenges in turbid samples due to overwhelming elastic background light. Here, we introduce a common-path Birefringence-Induced Phase Delay (BIPD) filter to disentangle the polarization states of the Brillouin and Rayleigh signals, enabling the rejection of the background light using a polarizer. We demonstrate a 65 dB extinction ratio in a single optical pass collecting Brillouin spectra in extremely scattering environments and across highly reflective interfaces. We further employ the BIPD filter to image bone tissues from a mouse model of osteopetrosis, highlighting altered biomechanical properties compared to the healthy control. Results herald new opportunities in mechanobiology where turbid biological samples remain poorly characterized.
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Affiliation(s)
| | - Renzo Vanna
- CNR-Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Marco Ventura
- CNR-Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | | | - Cristina Sobacchi
- IRCCS Humanitas Research Hospital, via Manzoni 56, 20089, Rozzano (Milano), Italy
- CNR-Istituto di Ricerca Genetica e Biomedica (CNR-IRGB), UOS di Milano, via Fantoli 16/15, 20138, Milano, Italy
| | - Morteza Behrouzitabar
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Dario Polli
- Specto Photonics, Via Giulio e Corrado Venini 18, 20127, Milano, Italy
- CNR-Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
| | - Cristian Manzoni
- CNR-Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Giulio Cerullo
- CNR-Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy
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3
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Suanno G, Genna VG, Maurizi E, Dieh AA, Griffith M, Ferrari G. Cell therapy in the cornea: The emerging role of microenvironment. Prog Retin Eye Res 2024; 102:101275. [PMID: 38797320 DOI: 10.1016/j.preteyeres.2024.101275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024]
Abstract
The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.
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Affiliation(s)
- Giuseppe Suanno
- Vita-Salute San Raffaele University, Milan, Italy; Eye Repair Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Eleonora Maurizi
- Centre for Regenerative Medicine ''S. Ferrari'', University of Modena and Reggio Emilia, Modena, Italy
| | - Anas Abu Dieh
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada
| | - May Griffith
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada.
| | - Giulio Ferrari
- Vita-Salute San Raffaele University, Milan, Italy; Eye Repair Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy; Ophthalmology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
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4
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Komninou MA, Seiler TG, Enzmann V. Corneal biomechanics and diagnostics: a review. Int Ophthalmol 2024; 44:132. [PMID: 38478103 PMCID: PMC10937779 DOI: 10.1007/s10792-024-03057-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 02/16/2024] [Indexed: 03/17/2024]
Abstract
PURPOSE Corneal biomechanics is an emerging field and the interest into physical and biological interrelations in the anterior part of the eye has significantly increased during the past years. There are many factors that determine corneal biomechanics such as hormonal fluctuations, hydration and environmental factors. Other factors that can affect the corneas are the age, the intraocular pressure and the central corneal thickness. The purpose of this review is to evaluate the factors affecting corneal biomechanics and the recent advancements in non-destructive, in vivo measurement techniques for early detection and improved management of corneal diseases. METHODS Until recently, corneal biomechanics could not be directly assessed in humans and were instead inferred from geometrical cornea analysis and ex vivo biomechanical testing. The current research has made strides in studying and creating non-destructive and contactless techniques to measure the biomechanical properties of the cornea in vivo. RESULTS Research has indicated that altered corneal biomechanics contribute to diseases such as keratoconus and glaucoma. The identification of pathological corneas through the new measurement techniques is imperative for preventing postoperative complications. CONCLUSIONS Identification of pathological corneas is crucial for the prevention of postoperative complications. Therefore, a better understanding of corneal biomechanics will lead to earlier diagnosis of ectatic disorders, improve current refractive surgeries and allow for a better postoperative treatment.
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Affiliation(s)
- Maria Angeliki Komninou
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland
- Institute of Intensive Care Medicine, University Hospital Zurich & University of Zurich, Zurich, Switzerland
| | - Theo G Seiler
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland
- Klinik Für Augenheilkunde, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
- Institut Für Refraktive Und Opthalmo-Chirurgie (IROC), Zurich, Switzerland
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Volker Enzmann
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland.
- Department of BioMedical Research, University of Bern, Bern, Switzerland.
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5
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Martinez-Vidal L, Testi C, Pontecorvo E, Pederzoli F, Alchera E, Locatelli I, Venegoni C, Spinelli A, Lucianò R, Salonia A, Podestà A, Ruocco G, Alfano M. Progressive alteration of murine bladder elasticity in actinic cystitis detected by Brillouin microscopy. Sci Rep 2024; 14:484. [PMID: 38177637 PMCID: PMC10766652 DOI: 10.1038/s41598-023-51006-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/29/2023] [Indexed: 01/06/2024] Open
Abstract
Bladder mechanical properties are critical for organ function and tissue homeostasis. Therefore, alterations of tissue mechanics are linked to disease onset and progression. This study aims to characterize the tissue elasticity of the murine bladder wall considering its different anatomical components, both in healthy conditions and in actinic cystitis, a state characterized by tissue fibrosis. Here, we exploit Brillouin microscopy, an emerging technique in the mechanobiology field that allows mapping tissue mechanics at the microscale, in non-contact mode and free of labeling. We show that Brillouin imaging of bladder tissues is able to recognize the different anatomical components of the bladder wall, confirmed by histopathological analysis, showing different tissue mechanical properties of the physiological bladder, as well as a significant alteration in the presence of tissue fibrosis. Our results point out the potential use of Brillouin imaging on clinically relevant samples as a complementary technique to histopathological analysis, deciphering complex mechanical alteration of each tissue layer of an organ that strongly relies on mechanical properties to perform its function.
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Affiliation(s)
- Laura Martinez-Vidal
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy.
- Università Vita-Salute San Raffaele, Via Olgettina, 60, 20132, Milan, Italy.
| | - Claudia Testi
- Center for Life Nano- and Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161, Roma, Italy.
| | - Emanuele Pontecorvo
- Center for Life Nano- and Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161, Roma, Italy
- CrestOptics S.p.A., Via Di Torre Rossa, 66, 00165, Roma, Italy
| | - Filippo Pederzoli
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
- Università Vita-Salute San Raffaele, Via Olgettina, 60, 20132, Milan, Italy
| | - Elisa Alchera
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Irene Locatelli
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Chiara Venegoni
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Antonello Spinelli
- Experimental Imaging Centre, San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy
| | - Roberta Lucianò
- Pathology Unit, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Andrea Salonia
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
- Università Vita-Salute San Raffaele, Via Olgettina, 60, 20132, Milan, Italy
| | - Alessandro Podestà
- Dipartimento Di Fisica "Aldo Pontremoli" and CIMAINA, Università Degli Studi Di Milano, 20133, Milan, Italy
| | - Giancarlo Ruocco
- Center for Life Nano- and Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161, Roma, Italy
- Dipartimento Di Fisica, Universitá Di Roma "La Sapienza", Piazzale Aldo Moro, 5, 00185, Roma, Italy
| | - Massimo Alfano
- Division of Experimental Oncology/Unit of Urology, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
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Cheburkanov V, Du J, Brogan DM, Berezin MY, Yakovlev VV. Toward peripheral nerve mechanical characterization using Brillouin imaging spectroscopy. NEUROPHOTONICS 2023; 10:035007. [PMID: 37635849 PMCID: PMC10460255 DOI: 10.1117/1.nph.10.3.035007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/29/2023]
Abstract
Significance Peripheral nerves are viscoelastic tissues with unique elastic characteristics. Imaging of peripheral nerve elasticity is important in medicine, particularly in the context of nerve injury and repair. Elasticity imaging techniques provide information about the mechanical properties of peripheral nerves, which can be useful in identifying areas of nerve damage or compression, as well as assessing the success of nerve repair procedures. Aim We aim to assess the feasibility of Brillouin microspectroscopy for peripheral nerve imaging of elasticity, with the ultimate goal of developing a new diagnostic tool for peripheral nerve injury in vivo. Approach Viscoelastic properties of the peripheral nerve were evaluated with Brillouin imaging spectroscopy. Results An external stress exerted on the fixed nerve resulted in a Brillouin shift. Quantification of the shift enabled correlation of the Brillouin parameters with nerve elastic properties. Conclusions Brillouin microscopy provides sufficient sensitivity to assess viscoelastic properties of peripheral nerves.
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Affiliation(s)
- Vsevolod Cheburkanov
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
| | - Junwei Du
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri, United States
- Washington University, Institute of Materials Science and Engineering, St. Louis, Missouri, United States
| | - David M. Brogan
- Washington University School of Medicine, Department of Orthopedic Surgery, St. Louis, Missouri, United States
| | - Mikhail Y. Berezin
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri, United States
- Washington University, Institute of Materials Science and Engineering, St. Louis, Missouri, United States
| | - Vladislav V. Yakovlev
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
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7
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Lin X, Mekonnen T, Verma S, Zevallos-Delgado C, Singh M, Aglyamov SR, Gesteira TF, Larin KV, Coulson-Thomas VJ. Hyaluronan Modulates the Biomechanical Properties of the Cornea. Invest Ophthalmol Vis Sci 2022; 63:6. [PMID: 36478198 PMCID: PMC9733656 DOI: 10.1167/iovs.63.13.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose Hyaluronan (HA) is a major constituent of the extracellular matrix (ECM) that has high viscosity and is essential for maintaining tissue hydration. In the cornea, HA is enriched in the limbal region and is a key component of the limbal epithelial stem cell niche. HA is upregulated after injury participating in the formation of the provisional matrix, and has a key role in regulating the wound healing process. This study investigated whether changes in the distribution of HA before and after injury affects the biomechanical properties of the cornea in vivo. Methods Corneas of wild-type (wt) mice and mice lacking enzymes involved in the biosynthesis of HA were analyzed before, immediately after, and 7 and 14 days after a corneal alkali burn (AB). The corneas were evaluated using both a ring light and fluorescein stain by in vivo confocal microscopy, optical coherence elastography (OCE), and immunostaining of corneal whole mounts. Results Our results show that wt mice and mice lacking HA synthase (Has)1 and 3 present an increase in corneal stiffness 7 and 14 days after AB without a significant increase in HA expression and absence of scarring at 14 days after AB. In contrast, mice lacking Has2 present a significant decrease in corneal stiffness, with a significant increase in HA expression and scarring at 14 days after AB. Conclusions Our findings show that the mechanical properties of the cornea are significantly modulated by changes in HA distribution following alkali burn.
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Affiliation(s)
- Xiao Lin
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Taye Mekonnen
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
| | - Sudhir Verma
- College of Optometry, University of Houston, Houston, Texas, United States,Department of Zoology, Deen Dayal Upadhyaya College, University of Delhi, Delhi, India
| | | | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
| | - Salavat R. Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, Texas, United States
| | - Tarsis F. Gesteira
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
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8
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Bhattacharjee P, Ahearne M. Influence of spiral topographies on human limbal-derived immortalized corneal epithelial cells. Exp Eye Res 2022; 225:109252. [PMID: 36150543 DOI: 10.1016/j.exer.2022.109252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/22/2022] [Accepted: 09/13/2022] [Indexed: 12/29/2022]
Abstract
Cells migrate from the limbus to the corneal epithelium following a centripetal pathway. Corneal epithelial cells tend to orientate in spiral or vortex patterns. However, when cultured in-vitro, limbal derived corneal epithelia do not tend to align or migrate in a spiral pattern. Here, we used soft lithography to create silk fibroin substrates with spiral topographies that direct the human limbal-derived immortalized corneal epithelial cells (hTCEpi) to form a spiral orientation. The impact of this topography on the cells was then characterized. The spiral patterns affected cytoskeletal organization, cell spreading, and nuclei shapes. Spiral width and numbers had a significant impact on proliferation of cells, their focal adhesion, their chromatin condensation, and number of actin filaments. Immunocytochemical staining showed that the spiral pattern enhanced the expression of markers associated with limbal stem cells. The current work illustrates micro spiral patterns can serve to control the nature of limbal derived epithelial cells by providing relevant biophysical cues.
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Affiliation(s)
- Promita Bhattacharjee
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland; Department of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Mark Ahearne
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland; Department of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, University of Dublin, Dublin, Ireland.
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9
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Robertson SYT, Roberts JS, Deng SX. Regulation of Limbal Epithelial Stem Cells: Importance of the Niche. Int J Mol Sci 2021; 22:11975. [PMID: 34769405 PMCID: PMC8584795 DOI: 10.3390/ijms222111975] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022] Open
Abstract
Limbal epithelial stem/progenitor cells (LSCs) reside in a niche that contains finely tuned balances of various signaling pathways including Wnt, Notch, BMP, Shh, YAP, and TGFβ. The activation or inhibition of these pathways is frequently dependent on the interactions of LSCs with various niche cell types and extracellular substrates. In addition to receiving molecular signals from growth factors, cytokines, and other soluble molecules, LSCs also respond to their surrounding physical structure via mechanotransduction, interaction with the ECM, and interactions with other cell types. Damage to LSCs or their niche leads to limbal stem cell deficiency (LSCD). The field of LSCD treatment would greatly benefit from an understanding of the molecular regulation of LSCs in vitro and in vivo. This review synthesizes current literature around the niche factors and signaling pathways that influence LSC function. Future development of LSCD therapies should consider all these niche factors to achieve improved long-term restoration of the LSC population.
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Affiliation(s)
| | | | - Sophie X. Deng
- Jules Stein Eye Institute, University of California, Los Angeles, CA 94143, USA; (S.Y.T.R.); (J.S.R.)
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Lopes BT, Bao F, Wang J, Liu X, Wang L, Abass A, Eliasy A, Elsheikh A. Review of in-vivo characterisation of corneal biomechanics. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021. [DOI: 10.1016/j.medntd.2021.100073] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Rioboó RJJ, Gontán N, Sanderson D, Desco M, Gómez-Gaviro MV. Brillouin Spectroscopy: From Biomedical Research to New Generation Pathology Diagnosis. Int J Mol Sci 2021; 22:8055. [PMID: 34360822 PMCID: PMC8347166 DOI: 10.3390/ijms22158055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/11/2021] [Accepted: 07/23/2021] [Indexed: 01/06/2023] Open
Abstract
Brillouin spectroscopy has recently gained considerable interest within the biomedical field as an innovative tool to study mechanical properties in biology. The Brillouin effect is based on the inelastic scattering of photons caused by their interaction with thermodynamically driven acoustic modes or phonons and it is highly dependent on the material's elasticity. Therefore, Brillouin is a contactless, label-free optic approach to elastic and viscoelastic analysis that has enabled unprecedented analysis of ex vivo and in vivo mechanical behavior of several tissues with a micrometric resolution, paving the way to a promising future in clinical diagnosis. Here, we comprehensively review the different studies of this fast-moving field that have been performed up to date to provide a quick guide of the current literature. In addition, we offer a general view of Brillouin's biomedical potential to encourage its further development to reach its implementation as a feasible, cost-effective pathology diagnostic tool.
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Affiliation(s)
- Rafael J. Jiménez Rioboó
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), C/Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain;
| | - Nuria Gontán
- Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; (N.G.); (D.S.)
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III, 28911 Madrid, Spain
| | - Daniel Sanderson
- Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; (N.G.); (D.S.)
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III, 28911 Madrid, Spain
| | - Manuel Desco
- Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; (N.G.); (D.S.)
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III, 28911 Madrid, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029 Madrid, Spain
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, 28029 Madrid, Spain
| | - Maria Victoria Gómez-Gaviro
- Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; (N.G.); (D.S.)
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III, 28911 Madrid, Spain
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12
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Paterson TE, Dhowre HS, Villanueva D, Holland JW, Reddy Kethiri A, Singh V, Claeyssens F, MacNeil S, Ortega Asencio I. Tuning Electrospun Substrate Stiffness for the Fabrication of a Biomimetic Amniotic Membrane Substitute for Corneal Healing. ACS APPLIED BIO MATERIALS 2021; 4:5638-5649. [DOI: 10.1021/acsabm.1c00436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Thomas E. Paterson
- Automatic Control and Systems Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
| | - Hala S. Dhowre
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Danilo Villanueva
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Joseph W. Holland
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Abhinav Reddy Kethiri
- Centre for Ocular Regeneration, Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India
| | - Vivek Singh
- Centre for Ocular Regeneration, Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India
| | - Frederik Claeyssens
- The Kroto Research Institute, North Campus, University of Sheffield, Sheffield S3 7HQ, United Kingdom
| | - Sheila MacNeil
- The Kroto Research Institute, North Campus, University of Sheffield, Sheffield S3 7HQ, United Kingdom
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13
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Xiang Y, Seow KLC, Paterson C, Török P. Multivariate analysis of Brillouin imaging data by supervised and unsupervised learning. JOURNAL OF BIOPHOTONICS 2021; 14:e202000508. [PMID: 33675294 DOI: 10.1002/jbio.202000508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/16/2021] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
Brillouin imaging relies on the reliable extraction of subtle spectral information from hyperspectral datasets. To date, the mainstream practice has been to use line fitting of spectral features to retrieve the average peak shift and linewidth parameters. Good results, however, depend heavily on sufficient signal-to-noise ratio and may not be applicable in complex samples that consist of spectral mixtures. In this work, we thus propose the use of various multivariate algorithms that can be used to perform supervised or unsupervised analysis of the hyperspectral data, with which we explore advanced image analysis applications, namely unmixing, classification and segmentation in a phantom and live cells. The resulting images are shown to provide more contrast and detail, and obtained on a timescale ∼102 faster than fitting. The estimated spectral parameters are consistent with those calculated from pure fitting.
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Affiliation(s)
- YuChen Xiang
- Blackett Laboratory, Department of Physics, Imperial College London, London, UK
| | - Kai Ling C Seow
- Blackett Laboratory, Department of Physics, Imperial College London, London, UK
| | - Carl Paterson
- Blackett Laboratory, Department of Physics, Imperial College London, London, UK
| | - Peter Török
- Division of Physics and Applied Physics, Nanyang Technological University, Nanyang, Singapore
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14
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Smith RJ, Pérez-Cota F, Marques L, Clark M. 3D phonon microscopy with sub-micron axial-resolution. Sci Rep 2021; 11:3301. [PMID: 33558575 PMCID: PMC7870650 DOI: 10.1038/s41598-021-82639-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/18/2021] [Indexed: 12/12/2022] Open
Abstract
Brillouin light scattering (BLS) is an emerging method for cell imaging and characterisation. It allows elasticity-related contrast, optical resolution and label-free operation. Phonon microscopy detects BLS from laser generated coherent phonon fields to offer an attractive route for imaging since, at GHz frequencies, the phonon wavelength is sub-optical. Using phonon fields to image single cells is challenging as the signal to noise ratio and acquisition time are often poor. However, recent advances in the instrumentation have enabled imaging of fixed and living cells. This work presents the first experimental characterisation of phonon-based axial resolution provided by the response to a sharp edge. The obtained axial resolution is up to 10 times higher than that of the optical system used to take the measurements. Validation of the results are obtained with various polymer objects, which are in good agreement with those obtained using atomic force microscopy. Edge localisation, and hence profilometry, of a phantom boundary is measured with accuracy and precision of approximately 60 nm and 100 nm respectively. Finally, 3D imaging of fixed cells in culture medium is demonstrated.
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Affiliation(s)
- Richard J Smith
- Optics and Photonics, Faculty of Engineering, University of Nottingham, University Park, Nottingham, UK.
| | - Fernando Pérez-Cota
- Optics and Photonics, Faculty of Engineering, University of Nottingham, University Park, Nottingham, UK
| | - Leonel Marques
- Optics and Photonics, Faculty of Engineering, University of Nottingham, University Park, Nottingham, UK
| | - Matt Clark
- Optics and Photonics, Faculty of Engineering, University of Nottingham, University Park, Nottingham, UK
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15
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Nosrati H, Alizadeh Z, Nosrati A, Ashrafi-Dehkordi K, Banitalebi-Dehkordi M, Sanami S, Khodaei M. Stem cell-based therapeutic strategies for corneal epithelium regeneration. Tissue Cell 2020; 68:101470. [PMID: 33248403 DOI: 10.1016/j.tice.2020.101470] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 11/11/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022]
Abstract
Any significant loss of vision or blindness caused by corneal damages is referred to as corneal blindness. Corneal blindness is the fourth most common cause of blindness worldwide, representing more than 5% of the total blind population. Currently, corneal transplantation is used to treat many corneal diseases. In some cases, implantation of artificial cornea (keratoprosthesis) is suggested after a patient has had a donor corneal transplant failure. The shortage of donors and the side effects of keratoprosthesis are limiting these approaches. Recently, researchers have been actively pursuing new approaches for corneal regeneration because of these limitations. Nowadays, tissue engineering of different corneal layers (epithelium, stroma, endothelium, or full thickness tissue) is a promising approach that has attracted a great deal of interest from researchers and focuses on regenerative strategies using different cell sources and biomaterials. Various sources of corneal and non-corneal stem cells have shown significant advantages for corneal epithelium regeneration applications. Pluripotent stem cells (embryonic stem cells and iPS cells), epithelial stem cells (derived from oral mucus, amniotic membrane, epidermis and hair follicle), mesenchymal stem cells (bone marrow, adipose-derived, amniotic membrane, placenta, umbilical cord), and neural crest origin stem cells (dental pulp stem cells) are the most promising sources in this regard. These cells could also be used in combination with natural or synthetic scaffolds to improve the efficacy of the therapeutic approach. As the ocular surface is exposed to external damage, the number of studies on regeneration of the corneal epithelium is rising. In this paper, we reviewed the stem cell-based strategies for corneal epithelium regeneration.
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Affiliation(s)
- Hamed Nosrati
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran.
| | - Zohreh Alizadeh
- Endometrium and Endometriosis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Anatomical Sciences, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Ali Nosrati
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Korosh Ashrafi-Dehkordi
- Department of Molecular Medicine, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Mehdi Banitalebi-Dehkordi
- Department of Molecular Medicine, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Samira Sanami
- Department of Medical Biotechnology, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Mohammad Khodaei
- Department of Materials Science and Engineering, Golpayegan University of Technology, Golpayegan, Iran
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16
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MLL4-associated condensates counterbalance Polycomb-mediated nuclear mechanical stress in Kabuki syndrome. Nat Genet 2020; 52:1397-1411. [PMID: 33169020 PMCID: PMC7610431 DOI: 10.1038/s41588-020-00724-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 09/22/2020] [Indexed: 12/21/2022]
Abstract
The genetic elements required to tune gene expression are partitioned in active and repressive nuclear condensates. Chromatin compartments include transcriptional clusters whose dynamic establishment and functioning depend on multivalent interactions occurring among transcription factors, cofactors and basal transcriptional machinery. However, how chromatin players contribute to the assembly of transcriptional condensates is poorly understood. By interrogating the effect of KMT2D (also known as MLL4) haploinsufficiency in Kabuki syndrome, we found that mixed lineage leukemia 4 (MLL4) contributes to the assembly of transcriptional condensates through liquid-liquid phase separation. MLL4 loss of function impaired Polycomb-dependent chromatin compartmentalization, altering the nuclear architecture. By releasing the nuclear mechanical stress through inhibition of the mechanosensor ATR, we re-established the mechanosignaling of mesenchymal stem cells and their commitment towards chondrocytes both in vitro and in vivo. This study supports the notion that, in Kabuki syndrome, the haploinsufficiency of MLL4 causes an altered functional partitioning of chromatin, which determines the architecture and mechanical properties of the nucleus.
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17
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Gouveia RM, Connon CJ. Biomechanical Modulation Therapy-A Stem Cell Therapy Without Stem Cells for the Treatment of Severe Ocular Burns. Transl Vis Sci Technol 2020; 9:5. [PMID: 33240564 PMCID: PMC7671857 DOI: 10.1167/tvst.9.12.5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/07/2020] [Indexed: 12/16/2022] Open
Abstract
Ocular injuries caused by chemical and thermal burns are often unmanageable and frequently result in disfigurement, corneal haze/opacification, and vision loss. Currently, a considerable number of surgical and pharmacological approaches are available to treat such injuries at either an acute or a chronic stage. However, these existing interventions are mainly directed at (and limited to) suppressing corneal inflammation and neovascularization while promoting re-epithelialization. Reconstruction of the ocular surface represents a suitable but last-option recourse in cases where epithelial healing is severely impaired, such as due to limbal stem cell deficiency. In this concise review, we discuss how biomechanical modulation therapy (BMT) may represent a more effective approach to promoting the regeneration of ocular tissues affected by burn injuries via restoration of the limbal stem cell niche. Specifically, the scientific basis supporting this new therapeutic modality is described, along with our growing understanding of the role that tissue biomechanics plays in stem cell fate and function. The potential impact of BMT as a future treatment option for the management of injuries affecting tissue compliance is also further discussed.
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Affiliation(s)
- Ricardo M Gouveia
- Biosciences Institute, Faculty of Medical Sciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Che J Connon
- Biosciences Institute, Faculty of Medical Sciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
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18
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Pérez-Cota F, La Cavera III S, Naznin S, Fuentes-Domínguez R, Smith RJ, Clark M. Apparent attenuation by opto-acoustic defocus in phonon microscopy. PHOTOACOUSTICS 2020; 19:100180. [PMID: 32489857 PMCID: PMC7262445 DOI: 10.1016/j.pacs.2020.100180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 01/10/2020] [Accepted: 03/30/2020] [Indexed: 05/20/2023]
Abstract
Understanding the mechanical properties of biological cells is a challenging problem for the life sciences partly because there are limited methods for mapping elasticity with high resolution. Phonon microscopy is a form of Brillouin light scattering which uses coherent phonons for imaging with elasticity-related contrast, phonon resolution and without labels. It can measure material properties such as sound velocity, acoustic impedance and attenuation. To use it as a contrast mechanism in microscopy, high numerical aperture (NA) lenses are key to high resolution. However, increasing NA induces apparent attenuation, a premature decay of the detected signal. To reduce signal decay and quantify the sound attenuation coefficient in cells, it is necessary to understand the mechanisms that affect signal decay. Here we define opto-acoustic defocus as a signal decay mechanism and propose methods to achieve quantitative sound attenuation measurements, and to optimise in-depth imaging at high resolution which is crucial for cell imaging.
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19
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Xiang Y, Foreman MR, Török P. SNR enhancement in brillouin microspectroscopy using spectrum reconstruction. BIOMEDICAL OPTICS EXPRESS 2020; 11:1020-1031. [PMID: 32133235 PMCID: PMC7041457 DOI: 10.1364/boe.380798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/13/2019] [Accepted: 01/10/2020] [Indexed: 05/06/2023]
Abstract
Brillouin spectroscopy can suffer from low signal-to-noise ratios (SNRs). Such low SNRs can render common data analysis protocols unreliable, especially for SNRs below ∼10. In this work we exploit two denoising algorithms, namely maximum entropy reconstruction (MER) and wavelet analysis (WA), to improve the accuracy and precision in determination of Brillouin shifts and linewidth. Algorithm performance is quantified using Monte-Carlo simulations and benchmarked against the Cramér-Rao lower bound. Superior estimation results are demonstrated even at low SNRs (≥ 1). Denoising is furthermore applied to experimental Brillouin spectra of distilled water at room temperature, allowing the speed of sound in water to be extracted. Experimental and theoretical values were found to be consistent to within ±1% at unity SNR.
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Affiliation(s)
- YuChen Xiang
- Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, UK
| | - Matthew R. Foreman
- Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, UK
| | - Peter Török
- Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, UK
- School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University, Singapore
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20
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Zvietcovich F, Pongchalee P, Meemon P, Rolland JP, Parker KJ. Reverberant 3D optical coherence elastography maps the elasticity of individual corneal layers. Nat Commun 2019; 10:4895. [PMID: 31653846 PMCID: PMC6814807 DOI: 10.1038/s41467-019-12803-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 09/24/2019] [Indexed: 12/01/2022] Open
Abstract
The elasticity mapping of individual layers in the cornea using non-destructive elastography techniques advances diagnosis and monitoring of ocular diseases and treatments in ophthalmology. However, transient Lamb waves, currently used in most dynamic optical coherence and ultrasound elastography techniques, diminish the translation of wave speed into shear/Young’s modulus. Here, we present reverberant 3D optical coherence elastography (Rev3D-OCE), a novel approach leveraging the physical properties of diffuse fields in detecting elasticity gradients not only in the lateral direction, but also along the depth axis of the cornea. A Monte Carlo analysis, finite element simulations, and experiments in layered phantoms are conducted to validate the technique and to characterize the axial elastography resolution. Experiments in ex vivo porcine cornea at different intraocular pressures reveal that Rev3D-OCE enables the elastic characterization of single layers that matches the anatomical description of corneal layers with unprecedented contrast in the dynamic OCE field. Elastic mapping of individual layers of the cornea with elastography uses Lamb waves, which are dependent on the thickness of each layer and the direction of propagation. Here the authors present Reverberant 3D Optical Coherence Elastography to measure elasticity of single layers using waves propagating in all directions.
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Affiliation(s)
- Fernando Zvietcovich
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, 14627-0126, USA
| | | | - Panomsak Meemon
- Suranaree University of Technology, Nakhon Ratchasima, Thailand, 30000
| | - Jannick P Rolland
- The Institute of Optics, University of Rochester, Rochester, NY, 14627-0186, USA
| | - Kevin J Parker
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, 14627-0126, USA.
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21
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Sankaran J, Karampatzakis A, Rice SA, Wohland T. Quantitative imaging and spectroscopic technologies for microbiology. FEMS Microbiol Lett 2019; 365:4953418. [PMID: 29718275 DOI: 10.1093/femsle/fny075] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/23/2018] [Indexed: 12/17/2022] Open
Abstract
Light microscopy has enabled the observation of the structure and organisation of biofilms. Typically, the contrast in an image obtained from light microscopy is given by the time-averaged intensity that is effective in visualising the overall structure. Technological advancements in light microscopy have led to the creation of techniques that not only provide a static intensity image of the biofilm, but also enable one to quantify various dynamic physicochemical properties of biomolecules in microbial biofilms. Such light microscopy-based techniques can be grouped into two main classes, those that are based on luminescence and those that are based on scattering. Here, we review the fundamentals and applications of luminescence and scattering-based techniques, specifically, fluorescence lifetime imaging, Förster resonance energy transfer, fluorescence correlation spectroscopy, fluorescence recovery after photobleaching, single-particle tracking, transient state imaging, and Brillouin and Raman microscopy. These techniques provide information about the abundance, interactions and mobility of various molecules in the biofilms and also properties of the local microenvironment at optical resolution. Further, one could use any of these techniques to probe the real-time changes in these physical parameters upon the addition of external agents or at different stages during the growth of biofilms.
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Affiliation(s)
- Jagadish Sankaran
- Departments of Biological Sciences and Chemistry, National University of Singapore, Singapore 117558, Singapore.,Centre for BioImaging Sciences, National University of Singapore, Singapore 117557, Singapore
| | - Andreas Karampatzakis
- Centre for BioImaging Sciences, National University of Singapore, Singapore 117557, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Scott A Rice
- Singapore Centre for Environmental Life Sciences Engineering and School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.,ithree Institute, University of Technology, Sydney 2007, Australia
| | - Thorsten Wohland
- Departments of Biological Sciences and Chemistry, National University of Singapore, Singapore 117558, Singapore.,Centre for BioImaging Sciences, National University of Singapore, Singapore 117557, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
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22
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Abstract
Brillouin spectroscopy and imaging are emerging techniques in analytical science, biophotonics, and biomedicine. They are based on Brillouin light scattering from acoustic waves or phonons in the GHz range, providing a nondestructive contactless probe of the mechanics on a microscale. Novel approaches and applications of these techniques to the field of biomedical sciences are discussed, highlighting the theoretical foundations and experimental methods that have been developed to date. Acknowledging that this is a fast moving field, a comprehensive account of the relevant literature is critically assessed here.
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Affiliation(s)
- Francesca Palombo
- School
of Physics and Astronomy, University of
Exeter, Stocker Road, EX4 4QL Exeter, U.K.
| | - Daniele Fioretto
- Department
of Physics and Geology, University of Perugia, via Alessandro Pascoli, I-06123 Perugia, Italy
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23
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Seiler TG, Shao P, Eltony A, Seiler T, Yun SH. Brillouin Spectroscopy of Normal and Keratoconus Corneas. Am J Ophthalmol 2019; 202:118-125. [PMID: 30772345 DOI: 10.1016/j.ajo.2019.02.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 01/28/2019] [Accepted: 02/05/2019] [Indexed: 11/17/2022]
Abstract
PURPOSE To investigate the age dependence of Brillouin spectroscopy of the cornea and to compare normal and keratoconus corneas. DESIGN Retrospective case-control study. METHODS Study Population: Healthy patients and patients suffering from keratoconus seen at the Institut für Refraktive und Ophthalmo-Chirurgie (IROC) between December 2016 and March 2017. Brillouin frequency shifts of patients of 2 different groups were examined with Brillouin spectroscopy perpendicular to the corneal surface. Group 1 consisted of 47 healthy eyes, whereas Group 2 included 36 eyes with keratoconus of unclear progression. Besides Brillouin examinations, corneal tomographies were acquired so that correlations and comparisons between geometric parameters and Brillouin frequency shifts could be evaluated. MAIN OUTCOME MEASURES Corneal Brillouin frequency shifts averaged over full corneal thickness. RESULTS A significant correlation between age and central Brillouin frequency shift was identified (P = .011) with an increase in Brillouin frequency shift of 4 MHz per decade in normal corneas. Keratoconus corneas have a significantly reduced Brillouin frequency shift at the thinnest point compared to normal corneas (5.7072 ± 0.0214 vs 5.7236 ± 0.0146 GHz, P < .001). The Brillouin frequency shift at the point of maximum posterior elevation showed best correlation with geometry-derived keratoconus indices. The receiver operating characteristic curve analysis of Brillouin frequency shift showed substantially worse sensitivity and specificity compared to Kmax and thinnest pachymetry for keratoconus detection. CONCLUSION Noninvasive Brillouin spectroscopy adds clinical information about the biomechanical state of the cornea perpendicular to the surface. An age-dependent stiffening of the cornea has been found and keratoconus corneas are statistically significantly different from normal corneas, but for precise differentiating of keratoconus stages (including normal corneas) the method is currently neither specific nor sensitive enough. Further development including standardized mapping and establishment of new indices may increase the potential of Brillouin spectroscopy substantially.
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Affiliation(s)
- Theo G Seiler
- Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Zürich, Switzerland; Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Universitätsklinik für Augenheilkunde, Inselspital, Bern, Switzerland.
| | - Peng Shao
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Amira Eltony
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Theo Seiler
- Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Zürich, Switzerland
| | - Seok-Hyun Yun
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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24
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Wu PJ, Masouleh MI, Dini D, Paterson C, Török P, Overby DR, Kabakova IV. Detection of proteoglycan loss from articular cartilage using Brillouin microscopy, with applications to osteoarthritis. BIOMEDICAL OPTICS EXPRESS 2019; 10:2457-2466. [PMID: 31143498 PMCID: PMC6524605 DOI: 10.1364/boe.10.002457] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 05/05/2023]
Abstract
The degeneration of articular cartilage (AC) occurs in osteoarthritis (OA), which is a leading cause of pain and disability in middle-aged and older people. The early disease-related changes in cartilage extra-cellular matrix (ECM) start with depletion of proteoglycan (PG), leading to an increase in tissue hydration and permeability. These early compositional changes are small (<10%) and hence difficult to register with conventional non-invasive imaging technologies (magnetic resonance and ultrasound imaging). Here we apply Brillouin microscopy for detecting changes in the mechanical properties and composition of porcine AC. OA-like degradation is mimicked by enzymatic tissue digestion, and we compare Brillouin microscopy measurements against histological staining of PG depletion over varying digestion times and enzyme concentrations. The non-destructive nature of Brillouin imaging technology opens new avenues for creating minimally invasive arthroscopic devices for OA diagnostics and therapeutic monitoring.
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Affiliation(s)
- Pei-Jung Wu
- Department of Bioengineering, Imperial College London, London,
UK
- Department of Physics, Imperial College London, London,
UK
| | | | - Daniele Dini
- Department of Mechanical Engineering, Imperial College London, London,
UK
| | - Carl Paterson
- Department of Physics, Imperial College London, London,
UK
| | - Peter Török
- Department of Physics, Imperial College London, London,
UK
- Division of Physics & Applied Physics, Nanyang Technological University, Singapore,
Singapore
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, London,
UK
| | - Irina V. Kabakova
- Department of Physics, Imperial College London, London,
UK
- School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW,
Australia
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25
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YAP, ΔNp63, and β-Catenin Signaling Pathways Are Involved in the Modulation of Corneal Epithelial Stem Cell Phenotype Induced by Substrate Stiffness. Cells 2019; 8:cells8040347. [PMID: 31013745 PMCID: PMC6523807 DOI: 10.3390/cells8040347] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/05/2019] [Accepted: 04/10/2019] [Indexed: 12/11/2022] Open
Abstract
Recent studies have established that the phenotype of epithelial stem cells residing in the corneal periphery (the limbus) depends on this niche’s distinct biomechanical properties. However, the signaling pathways underlying this dependency are still poorly understood. To address this issue, we investigated the effect of substrate stiffness on the migration, proliferation, and molecular phenotype of human limbal epithelial stem cells (LESCs). Specifically, we demonstrated that cells grown on collagen-based substrates with limbus-like compliance showed higher proliferation and stratification and lower migration capabilities, as well as higher levels of pro-proliferative markers Ki67 and β-Catenin, and LESC markers ΔNp63, ABCG2, and CK15. In contrast, cells on stiffer substrates lost these stem/progenitor cell markers, but instead expressed the key mechanotransduction factor YAP, as well as elevated levels of BMP4, a promotor of cell differentiation known to be negatively regulated by Wnt/β-Catenin signaling. This data allowed us to propose a new model that integrates the various molecular pathways involved in LESC response to substrate stiffness. This model will potentially be a useful guide to future research on the mechanisms underlying LESC loss following fibrosis-causing injuries.
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26
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Gouveia RM, Lepert G, Gupta S, Mohan RR, Paterson C, Connon CJ. Assessment of corneal substrate biomechanics and its effect on epithelial stem cell maintenance and differentiation. Nat Commun 2019; 10:1496. [PMID: 30944320 PMCID: PMC6447573 DOI: 10.1038/s41467-019-09331-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 03/01/2019] [Indexed: 12/13/2022] Open
Abstract
Whilst demonstrated extensively in vitro, the control of cell behaviour via modulation of substrate compliance in live tissues has not been accomplished to date. Here we propose that stem cells can be regulated solely through in situ modulation of tissue biomechanics. By first establishing, via high-resolution Brillouin spectro-microscopy, that the outer edge (limbus) of live human corneas has a substantially lower bulk modulus compared to their centre, we then demonstrate that this difference is associated with limbal epithelial stem cell (LESC) residence and YAP-dependent mechanotransduction. This phenotype-through-biomechanics correlation is further explored in vivo using a rabbit alkali burn model. Specifically, we show that treating the burnt surface of the cornea with collagenase effectively restores the tissue's mechanical properties and its capacity to support LESCs through mechanisms involving YAP suppression. Overall, these findings have extended implications for understanding stem cell niche biomechanics and its impact on tissue regeneration.
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Affiliation(s)
- Ricardo M Gouveia
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, NE1 3BZ, UK
| | - Guillaume Lepert
- The Blackett Laboratory, Imperial College London, London, SW7 2BW, UK
| | - Suneel Gupta
- Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, MO, USA
- College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, MO, USA
| | - Rajiv R Mohan
- Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, MO, USA
- College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, MO, USA
| | - Carl Paterson
- The Blackett Laboratory, Imperial College London, London, SW7 2BW, UK
| | - Che J Connon
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, NE1 3BZ, UK.
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27
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Ballmann CW, Meng Z, Yakovlev VV. Nonlinear Brillouin spectroscopy: what makes it a better tool for biological viscoelastic measurements. BIOMEDICAL OPTICS EXPRESS 2019; 10:1750-1759. [PMID: 31086701 PMCID: PMC6484976 DOI: 10.1364/boe.10.001750] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/01/2019] [Accepted: 02/01/2019] [Indexed: 05/24/2023]
Abstract
Brillouin spectroscopy is an emerging tool in biomedical imaging and sensing. It is capable of assessing the high-frequency viscoelastic longitudinal modulus with microscopic spatial resolution. Nonlinear Brillouin spectroscopy based on impulsive stimulated Brillouin scattering offers a number of significant advantages over conventional spontaneous and stimulated Brillouin scattering. In this report, we evaluate the accuracy of Brillouin shift measurements in spontaneous and nonlinear Brillouin microscopy by calculating the Allan variance for both CW excited spontaneous Brillouin measurements and nonlinear Brillouin scattering measurements made with both nanosecond and picosecond pulse excitation. We find that impulsive stimulated Brillouin spectroscopy is superior to spontaneous Brillouin spectroscopy in terms of the accuracy of such measurements and demonstrate its application for assessing tiny changes in Brillouin frequency shifts associated with low concentrations of biologically relevant solutions.
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Affiliation(s)
| | - Zhaokai Meng
- Texas A&M University, College Station, TX 77843-4242,
USA
| | - Vladislav V. Yakovlev
- Texas A&M University, College Station, TX 77843-4242,
USA
- Zhejiang University, Hangzhou, Zhejiang 310027,
China
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Nikolić M, Scarcelli G. Long-term Brillouin imaging of live cells with reduced absorption-mediated damage at 660 nm wavelength. BIOMEDICAL OPTICS EXPRESS 2019; 10:1567-1580. [PMID: 31086695 PMCID: PMC6484981 DOI: 10.1364/boe.10.001567] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 05/18/2023]
Abstract
In Brillouin microscopy, absorption-induced photodamage of incident light is the primary limitation on signal-to-noise ratio in many practical scenarios. Here we show that 660 nm may represent an optimal wavelength for Brillouin microscopy as it offers minimal absorption-mediated photodamage at high Brillouin scattering efficiency and the possibility to use a pure and narrow laser line from solid-state lasing medium. We demonstrate that live cells are ~80 times less susceptible to the 660 nm incident light compared to 532 nm light, which overall allows Brillouin imaging of up to more than 30 times higher SNR. We show that this improvement enables Brillouin imaging of live biological samples with improved accuracy, higher speed and/or larger fields of views with denser sampling.
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Affiliation(s)
- Miloš Nikolić
- Maryland Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Giuliano Scarcelli
- Maryland Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
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Fiore A, Scarcelli G. Single etalon design for two-stage cross-axis VIPA spectroscopy. BIOMEDICAL OPTICS EXPRESS 2019; 10:1475-1481. [PMID: 30891361 PMCID: PMC6420281 DOI: 10.1364/boe.10.001475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/08/2019] [Accepted: 02/08/2019] [Indexed: 05/15/2023]
Abstract
Two-stage cross axis VIPA spectrometers have been widely used in Brillouin microscopy since they provide single shot spectral measurements at high throughput and extinction. However, this spectrometer configuration presents challenges such as size, cost and alignment difficulties between the two cascaded etalons. Here, we present a cross-axis VIPA spectrometer that implements a single etalon, using a light recirculation architecture to achieve the multistage configuration.
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Affiliation(s)
- Antonio Fiore
- Fischell Department of Bioengineering, University of Maryland, 8278 Paint Branch Drive, College Park, MD 20742, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, 8278 Paint Branch Drive, College Park, MD 20742, USA
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30
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Evolution of the vertebrate corneal stroma. Prog Retin Eye Res 2018; 64:65-76. [DOI: 10.1016/j.preteyeres.2018.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/14/2022]
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31
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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] [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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32
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Karampatzakis A, Song CZ, Allsopp LP, Filloux A, Rice SA, Cohen Y, Wohland T, Török P. Probing the internal micromechanical properties of Pseudomonas aeruginosa biofilms by Brillouin imaging. NPJ Biofilms Microbiomes 2017; 3:20. [PMID: 28900539 PMCID: PMC5591272 DOI: 10.1038/s41522-017-0028-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 12/17/2022] Open
Abstract
Biofilms are organised aggregates of bacteria that adhere to each other or surfaces. The matrix of extracellular polymeric substances that holds the cells together provides the mechanical stability of the biofilm. In this study, we have applied Brillouin microscopy, a technique that is capable of measuring mechanical properties of specimens on a micrometre scale based on the shift in frequency of light incident upon a sample due to thermal fluctuations, to investigate the micromechanical properties of an active, live Pseudomonas aeruginosa biofilm. Using this non-contact and label-free technique, we have extracted information about the internal stiffness of biofilms under continuous flow. No correlation with colony size was found when comparing the averages of Brillouin shifts of two-dimensional cross-sections of randomly selected colonies. However, when focusing on single colonies, we observed two distinct spatial patterns: in smaller colonies, stiffness increased towards their interior, indicating a more compact structure of the centre of the colony, whereas, larger (over 45 μm) colonies were found to have less stiff interiors. A specialized microscopy technique can monitor biofilm stiffness in a non-destructive manner, yielding insights into biofilm structure and development. The technique, called Brillouin imaging, uses changes in the frequency of light interacting with a substance to reveal fine detail about the material’s mechanical properties. Peter Török and colleagues at Imperial College London, with co-workers in Singapore, used Brillouin imaging to study biofilms of Pseudomonas aeruginosa bacteria at different stages in their life cycle. In young colonies, stiffness increased towards the interior of the biofilm, while mature colonies had less stiff interiors. The older biofilms may therefore have hollow interiors or may have been moving towards a phase of bacterial dispersal from the biofilm state. This non-disruptive method to study mechanical variations within and between living biofilms may help efforts to combat biofilms in clinical, environmental and industrial situations.
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Affiliation(s)
- A Karampatzakis
- Centre for BioImaging Sciences, National University of Singapore, Singapore, 117557 Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 117557 Singapore.,Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2BZ United Kingdom
| | - C Z Song
- Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2BZ United Kingdom
| | - L P Allsopp
- Imperial College London, Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, South Kensington Campus, Flowers Building, SW7 2AZ London, United Kingdom
| | - A Filloux
- Imperial College London, Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, South Kensington Campus, Flowers Building, SW7 2AZ London, United Kingdom
| | - S A Rice
- Singapore Centre for Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University Singapore, Singapore, 637551 Singapore
| | - Y Cohen
- Singapore Centre for Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University Singapore, Singapore, 637551 Singapore
| | - T Wohland
- Centre for BioImaging Sciences, National University of Singapore, Singapore, 117557 Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 117557 Singapore.,Department of Biological Sciences and Department of Chemistry, National University of Singapore, Singapore, 117346 Singapore
| | - P Török
- Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2BZ United Kingdom
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33
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Bottari C, Comez L, Corezzi S, D'Amico F, Gessini A, Mele A, Punta C, Melone L, Pugliese A, Masciovecchio C, Rossi B. Correlation between collective and molecular dynamics in pH-responsive cyclodextrin-based hydrogels. Phys Chem Chem Phys 2017; 19:22555-22563. [DOI: 10.1039/c7cp04190j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The joint use of UV Raman and Brillouin scattering experiments is employed to explore phase evolutions in pH-responsive polysaccharide hydrogels.
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Affiliation(s)
- C. Bottari
- Elettra – Sincrotrone Trieste
- 34149 Trieste
- Italy
- Department of Physics
- University of Trieste
| | - L. Comez
- IOM-CNR c/o Department of Physics and Geology
- University of Perugia
- 06123 Perugia
- Italy
| | - S. Corezzi
- Department of Physics and Geology
- University of Perugia
- 06123 Perugia
- Italy
| | - F. D'Amico
- Elettra – Sincrotrone Trieste
- 34149 Trieste
- Italy
| | - A. Gessini
- Elettra – Sincrotrone Trieste
- 34149 Trieste
- Italy
| | - A. Mele
- Department of Chemistry
- Materials and Chemical Engineering “G. Natta”
- Politecnico di Milano and INSTM Local Unit
- Milano
- Italy
| | - C. Punta
- Department of Chemistry
- Materials and Chemical Engineering “G. Natta”
- Politecnico di Milano and INSTM Local Unit
- Milano
- Italy
| | - L. Melone
- Department of Chemistry
- Materials and Chemical Engineering “G. Natta”
- Politecnico di Milano and INSTM Local Unit
- Milano
- Italy
| | - A. Pugliese
- Department of Chemistry
- Materials and Chemical Engineering “G. Natta”
- Politecnico di Milano and INSTM Local Unit
- Milano
- Italy
| | | | - B. Rossi
- Elettra – Sincrotrone Trieste
- 34149 Trieste
- Italy
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