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Dilley KK, Prasad KR, Nguyen TV, Stokolosa A, Borden PA, Heur JM, Kim S, Hill MG, Wong BJF. Second harmonic generation microscopy of electromechanical reshaping on corneal collagen. Exp Eye Res 2024; 244:109941. [PMID: 38782177 DOI: 10.1016/j.exer.2024.109941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 05/25/2024]
Abstract
Refractive errors remain a global health concern, as a large proportion of the world's population is myopic. Current ablative approaches are costly, not without risks, and not all patients are candidates for these procedures. Electromechanical reshaping (EMR) has been explored as a viable cost-effective modality to directly shape tissues, including cartilage. In this study, stromal collagen structure and fibril orientation was examined before and after EMR with second-harmonic generation microscopy (SHG), a nonlinear multiphoton imaging method that has previously been used to study native corneal collagen with high spatial resolution. EMR, using a milled metal contact lens and potentiostat, was performed on the corneas of five extracted rabbit globes. SHG was performed using a confocal microscopy system and all images underwent collagen fibril orientation analysis. The collagen SHG signal in controls is uniform and is similarly seen in samples treated with pulsed potential, while continuous EMR specimens have reduced, nonhomogeneous signal. Collagen fibril orientation in native tissue demonstrates a broad distribution with suggestion of another peak evolving, while with EMR treated eyes a bimodal characteristic becomes readily evident. Pulsed EMR may be a means to correct refractive errors, as when comparing its SHG signal to negative control, preservation of collagen structures with little to no damage is observed. From collagen fiber orientation analysis, it can be inferred that simple DC application alters the structure of collagen. Future studies will involve histological assessment of these layers and multi-modal imaging analysis of dosimetry.
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Affiliation(s)
- Katelyn K Dilley
- Beckman Laser Institute & Medical Clinic, University of California - Irvine, CA, 92612, USA
| | - Karthik R Prasad
- Beckman Laser Institute & Medical Clinic, University of California - Irvine, CA, 92612, USA; School of Medicine, University of California - Irvine, Irvine, CA, 92617, USA
| | - Theodore V Nguyen
- Beckman Laser Institute & Medical Clinic, University of California - Irvine, CA, 92612, USA; School of Medicine, University of California - Irvine, Irvine, CA, 92617, USA
| | - Anna Stokolosa
- Department of Biomedical Engineering, University of California - Irvine, Irvine, CA, 92697, USA
| | - Pamela A Borden
- Beckman Laser Institute & Medical Clinic, University of California - Irvine, CA, 92612, USA; Department of Biomedical Engineering, University of California - Irvine, Irvine, CA, 92697, USA
| | - J Martin Heur
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Sehwan Kim
- Department of Biomedical Engineering, Beckman Laser Institute Korea, Dankook University, Cheonan, 31116, Republic of Korea
| | - Michael G Hill
- Department of Chemistry, Occidental College, Los Angeles, CA, 90041, USA
| | - Brian J F Wong
- Beckman Laser Institute & Medical Clinic, University of California - Irvine, CA, 92612, USA; School of Medicine, University of California - Irvine, Irvine, CA, 92617, USA; Department of Biomedical Engineering, University of California - Irvine, Irvine, CA, 92697, USA; Department of Otolaryngology - Head and Neck Surgery, University of California - Irvine, School of Medicine, Orange, CA, 92868, USA.
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2
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Martínez-Ojeda RM, Prieto-Bonete G, Perez-Cárceles MD, Bueno JM. Structural changes in the crystalline lens as a function of the postmortem interval assessed with two-photon imaging microscopy. BIOMEDICAL OPTICS EXPRESS 2024; 15:4318-4329. [PMID: 39022534 PMCID: PMC11249687 DOI: 10.1364/boe.524380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/28/2024] [Accepted: 06/03/2024] [Indexed: 07/20/2024]
Abstract
The properties and structure of the crystalline lens change as time after death passes. Some experiments have suggested that these might be used to estimate the postmortem interval (PMI). In this study, the organization and texture of the rabbit lens were objectively evaluated as a function of the PMI using two-photon excitation fluorescence (TPEF) imaging microscopy. Between 24 h and 72 h, the lens presented a highly organized structure, although the fiber delineation was progressively vanishing. At 96 h, this turned into a homogeneous pattern where fibers were hardly observed. This behaviour was similar for parameters providing information on tissue texture. On the other hand, the fiber density of the lens is linearly reduced with the PMI. On average, density at 24 h was approximately two-fold when compared to 96 h after death. The present results show that TPEF microscopy combined with different quantitative tools can be used to objectively monitor temporal changes in the lens fiber organization after death. This might help to estimate the PMI, which is one of the most complex problems in forensic science.
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Affiliation(s)
- Rosa M. Martínez-Ojeda
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | - Gemma Prieto-Bonete
- Servicio de Protección de la Naturaleza (SEPRONA), Guardia Civil, Ministerio del Interior, Spain
| | - María D. Perez-Cárceles
- Departamento de Medicina Legal y Forense, IMIB-Arrixaca, Facultad de Medicina, Universidad de Murcia, 30100 Murcia, Spain
| | - Juan M. Bueno
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
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3
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Bueno JM, Martínez-Ojeda RM, Pérez-Zabalza M, García-Mendívil L, Asensio MC, Ordovás L, Pueyo E. Analysis of age-related changes in the left ventricular myocardium with multiphoton microscopy. BIOMEDICAL OPTICS EXPRESS 2024; 15:3251-3264. [PMID: 38855691 PMCID: PMC11161339 DOI: 10.1364/boe.509227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/27/2024] [Accepted: 03/11/2024] [Indexed: 06/11/2024]
Abstract
Aging induces cardiac remodeling, resulting in an increase in the risk of suffering heart diseases, including heart failure. Collagen deposition increases with age and, together with sarcomeric changes in cardiomyocytes, may lead to ventricular stiffness. Multiphoton (MP) microscopy is a useful technique to visualize and detect variations in cardiac structures in a label free fashion. Here, we propose a method based on MP imaging (both two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) modalities) to explore and objectively quantify age-related structural differences in various components of cardiac tissues. Results in transmural porcine left ventricle (LV) sections reveal significant differences when comparing samples from young and old animals. Collagen and myosin SHG signals in old specimens are respectively 3.8x and >6-fold larger than in young ones. Differences in TPEF signals from cardiomyocyte were ∼3x. Moreover, the increased amount of collagen in old specimens results in a more organized pattern when compared to young LV tissues. Since changes in collagen and myosin are associated with cardiac dysfunction, the technique used herein might be a useful tool to accurately predict and measure changes associated with age-related myocardium fibrosis, tissue remodeling and sarcomeric alterations, with potential implications in preventing heart disease.
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Affiliation(s)
- Juan M. Bueno
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | - Rosa M. Martínez-Ojeda
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | - María Pérez-Zabalza
- BSICoS group, I3A, IIS Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Centro Universitario de la Defensa (CUD), 50018 Zaragoza, Spain
| | | | - M. Carmen Asensio
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | - Laura Ordovás
- BSICoS group, I3A, IIS Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Fundación Agencia Aragonesa para la Investigación y el Desarrollo (ARAID), 50018 Zaragoza, Spain
| | - Esther Pueyo
- BSICoS group, I3A, IIS Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina, 50018 Zaragoza, Spain
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4
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Guimarães P, Morgado M, Batista A. On the quantitative analysis of lamellar collagen arrangement with second-harmonic generation imaging. BIOMEDICAL OPTICS EXPRESS 2024; 15:2666-2680. [PMID: 38633085 PMCID: PMC11019681 DOI: 10.1364/boe.516817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 04/19/2024]
Abstract
Second harmonic generation (SHG) allows for the examination of collagen structure in collagenous tissues. Collagen is a fibrous protein found in abundance in the human body, present in bones, cartilage, the skin, and the cornea, among other areas, providing structure, support, and strength. Its structural arrangement is deeply intertwined with its function. For instance, in the cornea, alterations in collagen organization can result in severe visual impairments. Using SHG imaging, various metrics have demonstrated the potential to study collagen organization. The discrimination between healthy, keratoconus, and crosslinked corneas, assessment of injured tendons, or the characterization of breast and ovarian tumorous tissue have been demonstrated. Nevertheless, these metrics have not yet been objectively evaluated or compared. A total of five metrics were identified and implemented from the literature, and an additional approach adapted from texture analysis was proposed. In this study, we analyzed their effectiveness on a ground-truth set of artificially generated fibrous images. Our investigation provides the first comprehensive assessment of the performance of multiple metrics, identifying both the strengths and weaknesses of each approach and providing valuable insights for future applications of SHG imaging in medical diagnostics and research.
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Affiliation(s)
- Pedro Guimarães
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Miguel Morgado
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
- Department of Physics, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
| | - Ana Batista
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
- Department of Physics, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
- Centre for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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5
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Kang H, Han Y, Jin M, Zheng L, Liu Z, Xue Y, Liu Z, Li C. Decellularized squid mantle scaffolds as tissue-engineered corneal stroma for promoting corneal regeneration. Bioeng Transl Med 2023; 8:e10531. [PMID: 37476050 PMCID: PMC10354768 DOI: 10.1002/btm2.10531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 07/22/2023] Open
Abstract
Corneal blindness is a worldwide major cause of vision loss, and corneal transplantation remains to be the most effective way to restore the vision. However, often there is a shortage of the donor corneas for transplantation. Therefore, it is urgent to develop a novel tissue-engineered corneal substitute. The present study envisaged the development of a novel and efficient method to prepare the corneal stromal equivalent from the marine biomaterials-squid. A chemical method was employed to decellularize the squid mantle scaffold to create a cell-free tissue substitute using 0.5% sodium dodecyl sulfate (SDS) solution. Subsequently, a novel clearing method, namely clear, unobstructed brain imaging cocktails (CUBIC) method was used to transparent it. Decellularized squid mantle scaffold (DSMS) has high decellularization efficiency, is rich in essential amino acids, and maintains the regular fiber alignment. In vitro experiments showed that the soaking solution of DSMS was non-toxic to human corneal epithelium cells. DSMS exhibited a good biocompatibility in the rat muscle by undergoing a complete degradation, and promoted the growth of the muscle. In addition, the DSMS showed a good compatibility with the corneal stroma in the rabbit inter-corneal implantation model, and promoted the regeneration of the corneal stroma without any evident rejection. Our results indicate that the squid mantle can be a potential new type of tissue-engineered corneal stroma material with a promising clinical application.
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Affiliation(s)
- Honghua Kang
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
| | - Yi Han
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
| | - Mengyi Jin
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
| | - Lan Zheng
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
| | - Zhen Liu
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
| | - Yuhua Xue
- School of Pharmaceutical SciencesXiamen UniversityXiamenChina
| | - Zuguo Liu
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
- Department of Ophthalmologythe First Affiliated Hospital of University of South ChinaHengyangHunanChina
| | - Cheng Li
- Eye Institute & Affiliated Xiamen Eye Center, School of MedicineXiamen UniversityXiamenChina
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, School of MedicineXiamen UniversityXiamenChina
- Department of Ophthalmologythe First Affiliated Hospital of University of South ChinaHengyangHunanChina
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6
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Martínez-Ojeda RM, Mugnier LM, Artal P, Bueno JM. Blind deconvolution of second harmonic microscopy images of the living human eye. BIOMEDICAL OPTICS EXPRESS 2023; 14:2117-2128. [PMID: 37206134 PMCID: PMC10191662 DOI: 10.1364/boe.486989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/17/2023] [Accepted: 03/19/2023] [Indexed: 05/21/2023]
Abstract
Second harmonic generation (SHG) imaging microscopy of thick biological tissues is affected by the presence of aberrations and scattering within the sample. Moreover, additional problems, such as uncontrolled movements, appear when imaging in-vivo. Deconvolution methods can be used to overcome these limitations under some conditions. In particular, we present here a technique based on a marginal blind deconvolution approach for improving SHG images obtained in vivo in the human eye (cornea and sclera). Different image quality metrics are used to quantify the attained improvement. Collagen fibers in both cornea and sclera are better visualized and their spatial distributions accurately assessed. This might be a useful tool to better discriminate between healthy and pathological tissues, especially those where changes in collagen distribution occur.
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Affiliation(s)
- Rosa M. Martínez-Ojeda
- Laboratorio de Óptica,
Instituto Universitario de Investigación en
Óptica y Nanofísica, Universidad de
Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | | | - Pablo Artal
- Laboratorio de Óptica,
Instituto Universitario de Investigación en
Óptica y Nanofísica, Universidad de
Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | - Juan M. Bueno
- Laboratorio de Óptica,
Instituto Universitario de Investigación en
Óptica y Nanofísica, Universidad de
Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
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7
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Batista A, Guimarães P, Domingues JP, Quadrado MJ, Morgado AM. Two-Photon Imaging for Non-Invasive Corneal Examination. SENSORS (BASEL, SWITZERLAND) 2022; 22:9699. [PMID: 36560071 PMCID: PMC9783858 DOI: 10.3390/s22249699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
Two-photon imaging (TPI) microscopy, namely, two-photon excited fluorescence (TPEF), fluorescence lifetime imaging (FLIM), and second-harmonic generation (SHG) modalities, has emerged in the past years as a powerful tool for the examination of biological tissues. These modalities rely on different contrast mechanisms and are often used simultaneously to provide complementary information on morphology, metabolism, and structural properties of the imaged tissue. The cornea, being a transparent tissue, rich in collagen and with several cellular layers, is well-suited to be imaged by TPI microscopy. In this review, we discuss the physical principles behind TPI as well as its instrumentation. We also provide an overview of the current advances in TPI instrumentation and image analysis. We describe how TPI can be leveraged to retrieve unique information on the cornea and to complement the information provided by current clinical devices. The present state of corneal TPI is outlined. Finally, we discuss the obstacles that must be overcome and offer perspectives and outlooks to make clinical TPI of the human cornea a reality.
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Affiliation(s)
- Ana Batista
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
- Department of Physics, Faculty of Science and Technology, University of Coimbra, 3004-516 Coimbra, Portugal
| | - Pedro Guimarães
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
| | - José Paulo Domingues
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
- Department of Physics, Faculty of Science and Technology, University of Coimbra, 3004-516 Coimbra, Portugal
| | - Maria João Quadrado
- Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra, 3004-561 Coimbra, Portugal
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - António Miguel Morgado
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
- Department of Physics, Faculty of Science and Technology, University of Coimbra, 3004-516 Coimbra, Portugal
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8
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Giraudet C, Diaz J, Le Tallec P, Allain JM. Multiscale mechanical model based on patient-specific geometry: Application to early keratoconus development. J Mech Behav Biomed Mater 2022; 129:105121. [DOI: 10.1016/j.jmbbm.2022.105121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/19/2022] [Accepted: 02/03/2022] [Indexed: 11/30/2022]
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Bueno JM, Ávila FJ, Lorenzo-Martín E, Gallego-Muñoz P, Carmen Martínez-García M. Assessment of the corneal collagen organization after chemical burn using second harmonic generation microscopy. BIOMEDICAL OPTICS EXPRESS 2021; 12:756-765. [PMID: 33680540 PMCID: PMC7901323 DOI: 10.1364/boe.412819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/22/2020] [Indexed: 05/11/2023]
Abstract
The organization of the corneal stoma is modified due to different factors, including pathology, surgery or external damage. Here the changes in the organization of the corneal collagen fibers during natural healing after chemical burn are investigated using second harmonic generation (SHG) imaging. Moreover, the structure tensor (ST) was used as an objective tool for morphological analyses at different time points after burn (up to 6 months). Unlike control corneas that showed a regular distribution, the collagen pattern at 1 month of burn presented a non-organized arrangement. SHG signal levels noticeably decreased and individual fibers were hardly visible. Over time, the healing process led to a progressive re-organization of the fibers that could be quantified through the ST. At 6 months, the stroma distribution reached values similar to those of control eyes and a dominant direction of the fibers re-appeared. The present results show that SHG microscopy imaging combined with the ST method is able to objectively monitor the temporal regeneration of the corneal organization after chemical burn. Future implementations of this approach into clinically adapted devices would help to diagnose and quantify corneal changes, not only due to chemical damages, but also as a result of disease or surgical procedures.
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Affiliation(s)
- Juan M. Bueno
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100 Murcia, Spain
| | | | - Elvira Lorenzo-Martín
- Dpto. Biología Celular, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, 47005 Valladolid, Spain
| | - Patricia Gallego-Muñoz
- Dpto. Biología Celular, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, 47005 Valladolid, Spain
| | - M. Carmen Martínez-García
- Dpto. Biología Celular, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, 47005 Valladolid, Spain
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Zeitoune AA, Bersanetti PA, Schor P, Erbes LA, Cesar CL, Adur J. Comparison of morphological changes of corneal collagen fibers treated with collagen crosslinking agents using second harmonic generation images. Int J Biol Macromol 2020; 165:346-353. [PMID: 32987082 DOI: 10.1016/j.ijbiomac.2020.09.147] [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: 07/23/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 10/23/2022]
Abstract
Corneal cross-linking (CXL) is a common surgical procedure used to modify corneal biomechanics and stabilize keratoconus progression which is still under discussion. Its side effects, which are mostly related to anatomical unpredictability and stromal exposure, are the reason for the search for new CXL agents. In this work we have quantitatively evaluated the porcine corneal stroma architecture treated with collagen crosslinking agents such as riboflavin solutions and açai extract, using second harmonic generation microscopy. Aimed at evaluating the morphological changes in the corneal stroma after collagen crosslinking under a CXL chemical agent, a tubeness filter based Hessian matrix to obtain a 3D fiber characterization of the SHG images was applied. The results showed a curling effect and shortening of the collagen fibers treated with açai as compared to the control. They also showed a higher degree of clustering of the collagen fibers with larger empty spaces when compared to the other two groups. We believe that studies such as these presented in this paper are a good direct nondestructive and free labeling evaluation technique that allows the observation of morphologic features of corneas treated with new CXL agents.
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Affiliation(s)
- Angel A Zeitoune
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (IBB), UNER, CONICET, Oro Verde, Entre Ríos, Argentina.
| | - Patrícia A Bersanetti
- Department of Biochemistry, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Paulo Schor
- Department of Ophthalmology and Visual Sciences, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Luciana A Erbes
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (IBB), UNER, CONICET, Oro Verde, Entre Ríos, Argentina.
| | - Carlos L Cesar
- Department of Physics of Federal University of Ceara (UFC), Brazil; INFABiC - National Institute of Science and Technology on Photonics Applied to Cell Biology, Campinas, Brazil
| | - Javier Adur
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (IBB), UNER, CONICET, Oro Verde, Entre Ríos, Argentina.
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11
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Seet LF, Chu SWL, Teng X, Toh LZ, Wong TT. Assessment of progressive alterations in collagen organization in the postoperative conjunctiva by multiphoton microscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:6495-6515. [PMID: 33282504 PMCID: PMC7687938 DOI: 10.1364/boe.403555] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 06/12/2023]
Abstract
Glaucoma filtration surgery (GFS) commonly fails due to excessive fibrosis. As collagen structure aberrations is implicated in adverse fibrotic progression, this study aims to uncover collagen organization alterations during postoperative scarring. Via quantitative second harmonic generation/two photon excitation multiphoton imaging, we reveal the scar development and phenotype in the mouse model of conjunctival scarring. We also show that multiphoton imaging corroborated the collagen ultrastructure anomaly characteristic of the SPARC-/- mouse postoperative conjunctiva. These data improve our understanding of postoperative conjunctival scarring and further enhance the utility of this model for the development of anti-fibrotic therapeutics for GFS.
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Affiliation(s)
- Li-Fong Seet
- Ocular Therapeutics and Drug Delivery, Singapore Eye Research Institute, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Duke-NUS Medical School, Singapore
- Co-corresponding authors
| | - Stephanie W L Chu
- Ocular Therapeutics and Drug Delivery, Singapore Eye Research Institute, Singapore
| | | | - Li Zhen Toh
- Ocular Therapeutics and Drug Delivery, Singapore Eye Research Institute, Singapore
| | - Tina T Wong
- Ocular Therapeutics and Drug Delivery, Singapore Eye Research Institute, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Duke-NUS Medical School, Singapore
- Glaucoma Service, Singapore National Eye Centre, Singapore
- Co-corresponding authors
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12
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Bueno JM, Ávila FJ, Hristu R, Stanciu SG, Eftimie L, Stanciu GA. Objective analysis of collagen organization in thyroid nodule capsules using second harmonic generation microscopy images and the Hough transform. APPLIED OPTICS 2020; 59:6925-6931. [PMID: 32788782 DOI: 10.1364/ao.393721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
Papillary carcinoma is the most prevalent type of thyroid cancer. Its diagnosis requires accurate and subjective analyses from expert pathologists. Here we propose a method based on the Hough transform (HT) to detect and objectively quantify local structural differences in collagen thyroid nodule capsules. Second harmonic generation (SHG) microscopy images were acquired on non-stained histological sections of capsule fragments surrounding the healthy thyroid gland and benign and tumoral/malignant nodules. The HT was applied to each SHG image to extract numerical information on the organization of the collagen architecture in the tissues under analysis. Results show that control thyroid capsule samples present a non-organized structure composed of wavy collagen distribution with local orientations. On the opposite, in capsules surrounding malignant nodules, a remodeling of the collagen network takes place and local undulations disappear, resulting in an aligned pattern with a global preferential orientation. The HT procedure was able to quantitatively differentiate thyroid capsules from capsules surrounding papillary thyroid carcinoma (PTC) nodules. Moreover, the algorithm also reveals that the collagen arrangement of the capsules surrounding benign nodules significantly differs from both the thyroid control and PTC nodule capsules. Combining SHG imaging with the HT results thus in an automatic and objective tool to discriminate between the pathological modifications that affect the capsules of thyroid nodules across the progressions of PTC, with potential to be used in clinical settings to complement current state-of-the-art diagnostic methods.
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