1
|
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.
Collapse
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
| |
Collapse
|
2
|
Ávila FJ, Bueno JM. Analysis and quantification of collagen organization with the structure tensor in second harmonic microscopy images of ocular tissues. APPLIED OPTICS 2015; 54:9848-54. [PMID: 26836548 DOI: 10.1364/ao.54.009848] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The important biological role of collagen-based tissues and the changes produced in the fiber distribution under particular situations (surgery, pathology, external damage, etc.) require tools for the analysis of the collagen organization that might potentially help in early diagnoses. Since collagen structures provide efficient second harmonic generation (SHG) signals, SHG microscopy has emerged as a powerful technique to visualize collagen fibers and qualitatively discriminate normal from abnormal tissues. Here we propose a quantitative method based on the structure tensor to quantify the different organization of collagen patterns in SHG images of ocular tissues. Results show that well-organized collagen distributions present a high degree of isotropy (DoI), a dominant orientation (PO), and a low structural dispersion (SD). On the other hand, the PO vanishes when the collagen tissue is not organized as a consequence of an increase in the SD and a decrease in the DoI. The proposed method is also able to discriminate partially organized samples. The combination of SHG microscopy and the structure tensor is a useful method to objectively classify collagen distributions. Clinical applications of this technique could help in the diagnosis and tracking of pathologies related to collagen disorders in connective tissue.
Collapse
|
3
|
Bueno JM, Palacios R, Pennos A, Artal P. Second-harmonic generation microscopy of photocurable polymer intrastromal implants in ex-vivo corneas. BIOMEDICAL OPTICS EXPRESS 2015; 6:2211-9. [PMID: 26114039 PMCID: PMC4473754 DOI: 10.1364/boe.6.002211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/14/2015] [Accepted: 05/14/2015] [Indexed: 05/25/2023]
Abstract
A custom adaptive-optics (AO) multiphoton microscope was used to visualize the corneal stroma after the insertion of a photocurable polymer material. A lamellar pocket was created and a certain amount of polymer in liquid form was injected. This turned into a rigid film after UV irradiation. Intact eyes were used as control. Tomographic and regular second harmonic generation (SHG) microscopy images were recorded from both control and corneas with polymer implants. In control corneas, the SHG signal decreased uniformly with depth. However, treated corneas exhibited an abrupt loss of SHG signal at the implant location. The use of AO increased the SHG levels and improved the visualization of the stroma, not only at deeper corneal layers but also beneath the implant. Moreover, the absence of SHG signal from the implant allowed its geometrical characterization (thickness and location). This technique offers a potential tool for non-invasive analysis of morphological changes in the cornea after surgery or treatment, and might be useful in future clinical environments.
Collapse
|
4
|
Palczewska G, Golczak M, Williams DR, Hunter JJ, Palczewski K. Endogenous fluorophores enable two-photon imaging of the primate eye. Invest Ophthalmol Vis Sci 2014; 55:4438-47. [PMID: 24970255 DOI: 10.1167/iovs.14-14395] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Noninvasive two-photon imaging of a living mammalian eye can reveal details of molecular processes in the retina and RPE. Retinyl esters and all-trans-retinal condensation products are two types of retinoid fluorophores present in these tissues. We measured the content of these two types of retinoids in monkey and human eyes to validate the potential of two-photon imaging for monitoring retinoid changes in human eyes. METHODS Two-photon microscopy (TPM) was used to visualize excised retina from monkey eyes. Retinoid composition and content in human and monkey eyes were quantified by HPLC and mass spectrometry (MS). RESULTS Clear images of inner and outer segments of rods and cones were obtained in primate eyes at different eccentricities. Fluorescence spectra from outer segments revealed a maximum emission at 480 nm indicative of retinols and their esters. In cynomolgus monkey and human retinal extracts, retinyl esters existed predominantly in the 11-cis configuration along with notable levels of 11-cis-retinol, a characteristic of cone-enriched retinas. Average amounts of di-retinoid-pyridinium-ethanolamine (A2E) in primate and human eyes were 160 and 225 pmol/eye, respectively. CONCLUSIONS These data show that human retina contains sufficient amounts of retinoids for two-photon excitation imaging. Greater amounts of 11-cis-retinyl esters relative to rodent retinas contribute to the fluorescence signal from both monkey and human eyes. These observations indicate that TPM imaging found effective in mice could detect early age- and disease-related changes in human retina.
Collapse
Affiliation(s)
| | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| |
Collapse
|
5
|
Hovhannisyan V, Guo HW, Hovhannisyan A, Ghukasyan V, Buryakina T, Chen YF, Dong CY. Photo-induced processes in collagen-hypericin system revealed by fluorescence spectroscopy and multiphoton microscopy. BIOMEDICAL OPTICS EXPRESS 2014; 5:1355-1362. [PMID: 24877000 PMCID: PMC4026910 DOI: 10.1364/boe.5.001355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 01/20/2014] [Accepted: 01/20/2014] [Indexed: 06/03/2023]
Abstract
Collagen is the main structural protein and the key determinant of mechanical and functional properties of tissues and organs. Proper balance between synthesis and degradation of collagen molecules is critical for maintaining normal physiological functions. In addition, collagen influences tumor development and drug delivery, which makes it a potential cancer therapy target. Using second harmonic generation, two-photon excited fluorescence microscopy, and spectrofluorimetry, we show that the natural pigment hypericin induces photosensitized destruction of collagen-based tissues. We demonstrate that hypericin-mediated processes in collagen fibers are irreversible and may be used for the treatment of cancer and collagen-related disorders.
Collapse
Affiliation(s)
- V. Hovhannisyan
- Department of Physics, National Taiwan University, Taipei106, Taiwan
| | - H. W. Guo
- Department of Physics, National Taiwan University, Taipei106, Taiwan
| | - A. Hovhannisyan
- Multimedia &Programming, European Regional Education Academy, Yerevan, Armenia
| | - V. Ghukasyan
- Neuroscience Center, University of North Carolina at Chapel Hill, NC USA
| | - T. Buryakina
- Department of Physics, National Taiwan University, Taipei106, Taiwan
| | - Y. F. Chen
- Department of Physics, National Taiwan University, Taipei106, Taiwan
| | - C. Y. Dong
- Department of Physics, National Taiwan University, Taipei106, Taiwan
- Center for Quantum Science and Engineering, National Taiwan University, Taipei 106, Taiwan
| |
Collapse
|
6
|
Meyer T, Schmitt M, Dietzek B, Popp J. Accumulating advantages, reducing limitations: multimodal nonlinear imaging in biomedical sciences - the synergy of multiple contrast mechanisms. JOURNAL OF BIOPHOTONICS 2013; 6:887-904. [PMID: 24259267 DOI: 10.1002/jbio.201300176] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 11/06/2013] [Indexed: 05/29/2023]
Abstract
Multimodal nonlinear microscopy has matured during the past decades to one of the key imaging modalities in life science and biomedicine due to its unique capabilities of label-free visualization of tissue structure and chemical composition, high depth penetration, intrinsic 3D sectioning, diffraction limited resolution and low phototoxicity. This review briefly summarizes first recent advances in the field regarding the methodology, e.g., contrast mechanisms and signal characteristics used for contrast generation as well as novel image processing approaches. The second part deals with technologic developments emphasizing improvements in penetration depth, imaging speed, spatial resolution and nonlinear labeling strategies. The third part focuses on recent applications in life science fundamental research and biomedical diagnostics as well as future clinical applications.
Collapse
Affiliation(s)
- Tobias Meyer
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | | | | | | |
Collapse
|
7
|
Bueno JM, Palacios R, Chessey MK, Ginis H. Analysis of spatial lamellar distribution from adaptive-optics second harmonic generation corneal images. BIOMEDICAL OPTICS EXPRESS 2013; 4:1006-13. [PMID: 23847727 PMCID: PMC3704083 DOI: 10.1364/boe.4.001006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/24/2013] [Accepted: 04/24/2013] [Indexed: 05/20/2023]
Abstract
The spatial organization of stromal collagen of ex-vivo corneas has been quantified in adaptive-optics second harmonic generation (SHG) images by means of an optimized Fourier transform (FT) based analysis. At a particular depth location, adjacent lamellae often present similar orientations and run parallel to the corneal surface. However this pattern might be combined with interweaved collagen bundles leading to crosshatched structures with different orientations. The procedure here reported provides us with both principal and crosshatched angles. This is also able to automatically distinguish a random distribution from a cross-shaped one, since it uses the ratio of the axes lengths of the best-fitted ellipse of the FT data as an auxiliary parameter. The technique has successfully been applied to SHG images of healthy corneas (both stroma and Bowman's layer) of different species and to corneas undergoing cross-linking treatment.
Collapse
|
8
|
Hillman EMC, Elson DS, Bigio IJ, Levenson RM, So PTC. Advances in optics for biotechnology, medicine and surgery. BIOMEDICAL OPTICS EXPRESS 2012; 3:531-532. [PMID: 22435099 PMCID: PMC3296539 DOI: 10.1364/boe.3.000531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 05/31/2023]
Abstract
The editors introduce the Biomedical Optics Express feature issue, "Advances in Optics for Biotechnology, Medicine and Surgery," which includes 12 contributions from attendees of the 2011 conference Advances in Optics for Biotechnology, Medicine and Surgery XII.
Collapse
Affiliation(s)
- Elizabeth M. C. Hillman
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Columbia University, New York, NY 10027, USA
| | - Daniel S. Elson
- Hamlyn Centre for Robotic Surgery, Department of Surgery, Imperial College London, SW7 2AZ, UK
| | - Irving J. Bigio
- Departments of Biomedical Engineering and Electrical & Computer Engineering, Boston University, Boston, MA 02215, USA
| | | | - Peter T. C. So
- Departments of Mechanical and Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02193, USA
| |
Collapse
|