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Campbell JM, Gosnell M, Agha A, Handley S, Knab A, Anwer AG, Bhargava A, Goldys EM. Label-Free Assessment of Key Biological Autofluorophores: Material Characteristics and Opportunities for Clinical Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2403761. [PMID: 38775184 DOI: 10.1002/adma.202403761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/04/2024] [Indexed: 06/13/2024]
Abstract
Autofluorophores are endogenous fluorescent compounds that naturally occur in the intra and extracellular spaces of all tissues and organs. Most have vital biological functions - like the metabolic cofactors NAD(P)H and FAD+, as well as the structural protein collagen. Others are considered to be waste products - like lipofuscin and advanced glycation end products - which accumulate with age and are associated with cellular dysfunction. Due to their natural fluorescence, these materials have great utility for enabling non-invasive, label-free assays with direct ties to biological function. Numerous technologies, with different advantages and drawbacks, are applied to their assessment, including fluorescence lifetime imaging microscopy, hyperspectral microscopy, and flow cytometry. Here, the applications of label-free autofluorophore assessment are reviewed for clinical and health-research applications, with specific attention to biomaterials, disease detection, surgical guidance, treatment monitoring, and tissue assessment - fields that greatly benefit from non-invasive methodologies capable of continuous, in vivo characterization.
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Affiliation(s)
- Jared M Campbell
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | | | - Adnan Agha
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Shannon Handley
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Aline Knab
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Ayad G Anwer
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Akanksha Bhargava
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Ewa M Goldys
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
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2
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Hong M, Chong SZ, Goh YY, Tong L. Two-Photon and Multiphoton Microscopy in Anterior Segment Diseases of the Eye. Int J Mol Sci 2024; 25:1670. [PMID: 38338948 PMCID: PMC10855705 DOI: 10.3390/ijms25031670] [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: 12/09/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024] Open
Abstract
Two-photon excitation microscopy (TPM) and multiphoton fluorescence microscopy (MPM) are advanced forms of intravital high-resolution functional microscopy techniques that allow for the imaging of dynamic molecular processes and resolve features of the biological tissues of interest. Due to the cornea's optical properties and the uniquely accessible position of the globe, it is possible to image cells and tissues longitudinally to investigate ocular surface physiology and disease. MPM can also be used for the in vitro investigation of biological processes and drug kinetics in ocular tissues. In corneal immunology, performed via the use of TPM, cells thought to be intraepithelial dendritic cells are found to resemble tissue-resident memory T cells, and reporter mice with labeled plasmacytoid dendritic cells are imaged to understand the protective antiviral defenses of the eye. In mice with limbal progenitor cells labeled by reporters, the kinetics and localization of corneal epithelial replenishment are evaluated to advance stem cell biology. In studies of the conjunctiva and sclera, the use of such imaging together with second harmonic generation allows for the delineation of matrix wound healing, especially following glaucoma surgery. In conclusion, these imaging models play a pivotal role in the progress of ocular surface science and translational research.
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Affiliation(s)
- Merrelynn Hong
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore;
- Training and Education Department, Singapore National Eye Centre, Singapore 168751, Singapore
| | - Shu Zhen Chong
- Singapore Immunology Network (SIgN), Agency for Science Technology and Research (A*STAR), Singapore 138632, Singapore;
| | - Yun Yao Goh
- Lee Kong Chian School of Medicine, National Technical University, Singapore 639798, Singapore;
| | - Louis Tong
- Corneal and External Diseases Department, Singapore National Eye Centre, Singapore 168751, Singapore
- Ocular Surface Group, Singapore Eye Research Institute, Singapore 169856, Singapore
- Eye Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
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3
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Kaushik V, Dąbrowski M, Gessa L, Kumar N, Fernandes H. Two-photon excitation fluorescence in ophthalmology: safety and improved imaging for functional diagnostics. Front Med (Lausanne) 2024; 10:1293640. [PMID: 38235268 PMCID: PMC10791900 DOI: 10.3389/fmed.2023.1293640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/11/2023] [Indexed: 01/19/2024] Open
Abstract
Two-photon excitation fluorescence (TPEF) is emerging as a powerful imaging technique with superior penetration power in scattering media, allowing for functional imaging of biological tissues at a subcellular level. TPEF is commonly used in cancer diagnostics, as it enables the direct observation of metabolism within living cells. The technique is now widely used in various medical fields, including ophthalmology. The eye is a complex and delicate organ with multiple layers of different cell types and tissues. Although this structure is ideal for visual perception, it generates aberrations in TPEF eye imaging. However, adaptive optics can now compensate for these aberrations, allowing for improved imaging of the eyes of animal models for human diseases. The eye is naturally built to filter out harmful wavelengths, but these wavelengths can be mimicked and thereby utilized in diagnostics via two-photon (2Ph) excitation. Recent advances in laser-source manufacturing have made it possible to minimize the exposure of in vivo measurements within safety, while achieving sufficient signals to detect for functional images, making TPEF a viable option for human application. This review explores recent advances in wavefront-distortion correction in animal models and the safety of use of TPEF on human subjects, both of which make TPEF a potentially powerful tool for ophthalmological diagnostics.
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Affiliation(s)
- Vineeta Kaushik
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Michał Dąbrowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Luca Gessa
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Nelam Kumar
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Humberto Fernandes
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
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4
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Różanowska MB. Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina. Antioxidants (Basel) 2023; 12:2111. [PMID: 38136230 PMCID: PMC10740933 DOI: 10.3390/antiox12122111] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.
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Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, Wales, UK;
- Cardiff Institute for Tissue Engineering and Repair (CITER), Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
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5
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Engfer ZJ, Lewandowski D, Dong Z, Palczewska G, Zhang J, Kordecka K, Płaczkiewicz J, Panas D, Foik AT, Tabaka M, Palczewski K. Distinct mouse models of Stargardt disease display differences in pharmacological targeting of ceramides and inflammatory responses. Proc Natl Acad Sci U S A 2023; 120:e2314698120. [PMID: 38064509 PMCID: PMC10723050 DOI: 10.1073/pnas.2314698120] [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: 08/24/2023] [Accepted: 10/25/2023] [Indexed: 12/17/2023] Open
Abstract
Mutations in many visual cycle enzymes in photoreceptors and retinal pigment epithelium (RPE) cells can lead to the chronic accumulation of toxic retinoid byproducts, which poison photoreceptors and the underlying RPE if left unchecked. Without a functional ATP-binding cassette, sub-family A, member 4 (ABCA4), there is an elevation of all-trans-retinal and prolonged buildup of all-trans-retinal adducts, resulting in a retinal degenerative disease known as Stargardt-1 disease. Even in this monogenic disorder, there is significant heterogeneity in the time to onset of symptoms among patients. Using a combination of molecular techniques, we studied Abca4 knockout (simulating human noncoding disease variants) and Abca4 knock-in mice (simulating human misfolded, catalytically inactive protein variants), which serve as models for Stargardt-1 disease. We compared the two strains to ascertain whether they exhibit differential responses to agents that affect cytokine signaling and/or ceramide metabolism, as alterations in either of these pathways can exacerbate retinal degenerative phenotypes. We found different degrees of responsiveness to maraviroc, a known immunomodulatory CCR5 antagonist, and to the ceramide-lowering agent AdipoRon, an agonist of the ADIPOR1 and ADIPOR2 receptors. The two strains also display different degrees of transcriptional deviation from matched WT controls. Our phenotypic comparison of the two distinct Abca4 mutant-mouse models sheds light on potential therapeutic avenues previously unexplored in the treatment of Stargardt disease and provides a surrogate assay for assessing the effectiveness for genome editing.
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Affiliation(s)
- Zachary J. Engfer
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
- Department of Physiology and Biophysics, University of California, Irvine, CA92697
| | - Dominik Lewandowski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
| | - Zhiqian Dong
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
| | - Grazyna Palczewska
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
| | - Jianye Zhang
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
| | - Katarzyna Kordecka
- Ophthalmic Biology Group, International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw01-224, Poland
| | - Jagoda Płaczkiewicz
- Ophthalmic Biology Group, International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw01-224, Poland
| | - Damian Panas
- International Centre for Translational Eye Research, Warsaw01-224, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw01-224, Poland
| | - Andrzej T. Foik
- Ophthalmic Biology Group, International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw01-224, Poland
| | - Marcin Tabaka
- International Centre for Translational Eye Research, Warsaw01-224, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw01-224, Poland
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA92697
- Department of Physiology and Biophysics, University of California, Irvine, CA92697
- Department of Chemistry, University of California, Irvine, CA92697
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697
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6
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Zhang X, Xiao S, Guo Z, Yuan B, Wang X, Zhang S, Shi Y, Xing G, He T, Chen R. Improving the Five-Photon Absorption from Core-Shell Perovskite Nanocrystals. J Phys Chem Lett 2023; 14:7581-7590. [PMID: 37590125 DOI: 10.1021/acs.jpclett.3c01809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
It is necessary to improve the action cross section (η × σn) of high-order multiphoton absorption (MPA) for fundamental research and practical applications. Herein, the core-shell FAPbBr3/CsPbBr3 nanocrystals (NCs) were constructed, and fluorescence induced by up to five-photon absorption was observed. The value of η × σ5 reaches 8.64 × 10-139 cm10 s4 photon-4 nm-3 at 2300 nm, which is nearly an order of magnitude bigger than that of the core-only NCs. It is found that the increased dielectric constant promotes modulation of MPA effects, addressing the electronic distortion in high-order nonlinear behaviors through the local field effect. Meanwhile, the quasi-type-II band alignment suppresses the biexciton Auger recombination, ensuring the stronger MPA induced fluorescence. In addition, the core-shell structure can not only reduce the defect density but also promote the nonradiative energy transfer though the antenna-like effect. This work provides a new avenue for the exploitation of high-performance multiphoton excited nanomaterials for future photonic integration.
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Affiliation(s)
- Xuanyu Zhang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shuyu Xiao
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhihang Guo
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Baozhen Yuan
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xiongbin Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Samo Zhang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yueqing Shi
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guichuan Xing
- The Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau 519000, China
| | - Tingchao He
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Rui Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
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7
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Choi EH, Suh S, Sears AE, Hołubowicz R, Kedhar SR, Browne AW, Palczewski K. Genome editing in the treatment of ocular diseases. Exp Mol Med 2023; 55:1678-1690. [PMID: 37524870 PMCID: PMC10474087 DOI: 10.1038/s12276-023-01057-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/14/2023] [Indexed: 08/02/2023] Open
Abstract
Genome-editing technologies have ushered in a new era in gene therapy, providing novel therapeutic strategies for a wide range of diseases, including both genetic and nongenetic ocular diseases. These technologies offer new hope for patients suffering from previously untreatable conditions. The unique anatomical and physiological features of the eye, including its immune-privileged status, size, and compartmentalized structure, provide an optimal environment for the application of these cutting-edge technologies. Moreover, the development of various delivery methods has facilitated the efficient and targeted administration of genome engineering tools designed to correct specific ocular tissues. Additionally, advancements in noninvasive ocular imaging techniques and electroretinography have enabled real-time monitoring of therapeutic efficacy and safety. Herein, we discuss the discovery and development of genome-editing technologies, their application to ocular diseases from the anterior segment to the posterior segment, current limitations encountered in translating these technologies into clinical practice, and ongoing research endeavors aimed at overcoming these challenges.
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Affiliation(s)
- Elliot H Choi
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Susie Suh
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Avery E Sears
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Rafał Hołubowicz
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Sanjay R Kedhar
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Andrew W Browne
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA.
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA.
- Department of Chemistry, University of California, Irvine, CA, USA.
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, USA.
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8
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Palczewska G, Wojtkowski M, Palczewski K. From mouse to human: Accessing the biochemistry of vision in vivo by two-photon excitation. Prog Retin Eye Res 2023; 93:101170. [PMID: 36787681 PMCID: PMC10463242 DOI: 10.1016/j.preteyeres.2023.101170] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023]
Abstract
The eye is an ideal organ for imaging by a multi-photon excitation approach, because ocular tissues such as the sclera, cornea, lens and neurosensory retina, are highly transparent to infrared (IR) light. The interface between the retina and the retinal pigment epithelium (RPE) is especially informative, because it reflects the health of the visual (retinoid) cycle and its changes in response to external stress, genetic manipulations, and drug treatments. Vitamin A-derived retinoids, like retinyl esters, are natural fluorophores that respond to multi-photon excitation with near IR light, bypassing the filter-like properties of the cornea, lens, and macular pigments. Also, during natural aging some retinoids form bisretinoids, like diretinoid-pyridiniumethanolamine (A2E), that are highly fluorescent. These bisretinoids appear to be elevated concurrently with aging. Vitamin A-derived retinoids and bisretinoidss are detected by two-photon ophthalmoscopy (2PO), using a new class of light sources with adjustable spatial, temporal, and spectral properties. Furthermore, the two-photon (2P) absorption of IR light by the visual pigments in rod and cone photoreceptors can initiate visual transduction by cis-trans isomerization of retinal, enabling parallel functional studies. Recently we overcame concerns about safety, data interpretation and complexity of the 2P-based instrumentation, the major roadblocks toward advancing this modality to the clinic. These imaging and retina-function assessment advancements have enabled us to conduct the first 2P studies with humans.
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Affiliation(s)
- Grazyna Palczewska
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA; International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland; Polgenix, Inc., Department of Medical Devices, Cleveland, OH, USA; Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.
| | - Maciej Wojtkowski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland; Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland; Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland.
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA; Department of Physiology & Biophysics, School of Medicine, And Chemistry, Molecular Biology and Biochemistry, University of California, Irvine, CA, USA.
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9
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Stability of retinol in liposomes as measured by fluorescence lifetime spectroscopy and FLIM. BBA ADVANCES 2023. [DOI: 10.1016/j.bbadva.2023.100088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023] Open
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10
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Meah A, Boodram V, Bucinca-Cupallari F, Lim H. Axonal architecture of the mouse inner retina revealed by second harmonic generation. PNAS NEXUS 2022; 1:pgac160. [PMID: 36106183 PMCID: PMC9463061 DOI: 10.1093/pnasnexus/pgac160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/11/2022] [Indexed: 01/29/2023]
Abstract
We describe a novel method for visualizing the network of axons in the unlabeled fresh wholemount retina. The intrinsic radiation of second harmonic generation (SHG) was utilized to visualize single axons of all major retinal neurons, i.e., photoreceptors, horizontal cells, bipolar cells, amacrine cells, and the retinal ganglion cells. The cell types of SHG+ axons were determined using transgenic GFP/YFP mice. New findings were obtained with retinal SHG imaging: Müller cells do not maintain uniformly polarized microtubules in the processes; SHG+ axons of bipolar cells terminate in the inner plexiform layer (IPL) in a subtype-specific manner; a subset of amacrine cells, presumably the axon-bearing types, emits SHG; and the axon-like neurites of amacrine cells provide a cytoskeletal scaffolding for the IPL stratification. To demonstrate the utility, retinal SHG imaging was applied to testing whether the inner retina is preserved in glaucoma, using DBA/2 mice as a model of glaucoma and DBA/2-Gpnmb+ as the nonglaucomatous control. It was found that the morphology of the inner retina was largely intact in glaucoma and the presynaptic compartments to the retinal ganglion cells were uncompromised. It proves retinal SHG imaging as a promising technology for studying the physiological and diseased retinas in 3D.
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Affiliation(s)
- Arafat Meah
- Department of Physics and Astronomy, Hunter College, New York, NY 10065, USA
| | - Vinessia Boodram
- Department of Physics and Astronomy, Hunter College, New York, NY 10065, USA
| | - Festa Bucinca-Cupallari
- Department of Physics and Astronomy, Hunter College, New York, NY 10065, USA,The Graduate Centre of the City University of New York, New York, NY 10065, USA
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11
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Samimi K, Pattnaik BR, Capowski EE, Saha K, Gamm DM, Skala MC. In situ autofluorescence lifetime assay of a photoreceptor stimulus response in mouse retina and human retinal organoids. BIOMEDICAL OPTICS EXPRESS 2022; 13:3476-3492. [PMID: 35781966 PMCID: PMC9208582 DOI: 10.1364/boe.455783] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/25/2022] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Photoreceptors are the key functional cell types responsible for the initiation of vision in the retina. Phototransduction involves isomerization and conversion of vitamin A compounds, known as retinoids, and their recycling through the visual cycle. We demonstrate a functional readout of the visual cycle in photoreceptors within stem cell-derived retinal organoids and mouse retinal explants based on spectral and lifetime changes in autofluorescence of the visual cycle retinoids after exposure to light or chemical stimuli. We also apply a simultaneous two- and three-photon excitation method that provides specific signals and increases contrast between these retinoids, allowing for reliable detection of their presence and conversion within photoreceptors. This multiphoton imaging technique resolves the slow dynamics of visual cycle reactions and can enable high-throughput functional screening of retinal tissues and organoid cultures with single-cell resolution.
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Affiliation(s)
- Kayvan Samimi
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Bikash R. Pattnaik
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Krishanu Saha
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - David M. Gamm
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Melissa C. Skala
- Morgridge Institute for Research, Madison, WI 53715, USA
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
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12
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Xue Y, Browne AW, Tang WC, Delgado J, McLelland BT, Nistor G, Chen JT, Chew K, Lee N, Keirstead HS, Seiler MJ. Retinal Organoids Long-Term Functional Characterization Using Two-Photon Fluorescence Lifetime and Hyperspectral Microscopy. Front Cell Neurosci 2021; 15:796903. [PMID: 34955757 PMCID: PMC8707055 DOI: 10.3389/fncel.2021.796903] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/26/2021] [Indexed: 12/31/2022] Open
Abstract
Pluripotent stem cell-derived organoid technologies have opened avenues to preclinical basic science research, drug discovery, and transplantation therapy in organ systems. Stem cell-derived organoids follow a time course similar to species-specific organ gestation in vivo. However, heterogeneous tissue yields, and subjective tissue selection reduce the repeatability of organoid-based scientific experiments and clinical studies. To improve the quality control of organoids, we introduced a live imaging technique based on two-photon microscopy to non-invasively monitor and characterize retinal organoids’ (RtOgs’) long-term development. Fluorescence lifetime imaging microscopy (FLIM) was used to monitor the metabolic trajectory, and hyperspectral imaging was applied to characterize structural and molecular changes. We further validated the live imaging experimental results with endpoint biological tests, including quantitative polymerase chain reaction (qPCR), single-cell RNA sequencing, and immunohistochemistry. With FLIM results, we analyzed the free/bound nicotinamide adenine dinucleotide (f/b NADH) ratio of the imaged regions and found that there was a metabolic shift from glycolysis to oxidative phosphorylation. This shift occurred between the second and third months of differentiation. The total metabolic activity shifted slightly back toward glycolysis between the third and fourth months and stayed relatively stable between the fourth and sixth months. Consistency in organoid development among cell lines and production lots was examined. Molecular analysis showed that retinal progenitor genes were expressed in all groups between days 51 and 159. Photoreceptor gene expression emerged around the second month of differentiation, which corresponded to the shift in the f/b NADH ratio. RtOgs between 3 and 6 months of differentiation exhibited photoreceptor gene expression levels that were between the native human fetal and adult retina gene expression levels. The occurrence of cone opsin expression (OPN1 SW and OPN1 LW) indicated the maturation of photoreceptors in the fourth month of differentiation, which was consistent with the stabilized level of f/b NADH ratio starting from 4 months. Endpoint single-cell RNA and immunohistology data showed that the cellular compositions and lamination of RtOgs at different developmental stages followed those in vivo.
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Affiliation(s)
- Yuntian Xue
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States.,Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States
| | - Andrew W Browne
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States.,Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States.,Institute for Clinical and Translational Science, University of California, Irvine, Irvine, CA, United States
| | - William C Tang
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States
| | - Jeffrey Delgado
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States
| | | | | | - Jacqueline T Chen
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States.,Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States
| | - Kaylee Chew
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States
| | - Nicolas Lee
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, United States
| | | | - Magdalene J Seiler
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States.,Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States.,Department of Physical Medicine & Rehabilitation, University of California, Irvine, Irvine, CA, United States.,Department of Anatomy & Neurobiology, University of California, Irvine, Irvine, CA, United States
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13
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Boguslawski J, Palczewska G, Tomczewski S, Milkiewicz J, Kasprzycki P, Stachowiak D, Komar K, Marzejon MJ, Sikorski BL, Hudzikowski A, Głuszek A, Łaszczych Z, Karnowski K, Soboń G, Palczewski K, Wojtkowski M. In vivo imaging of the human eye using a two-photon excited fluorescence scanning laser ophthalmoscope. J Clin Invest 2021; 132:154218. [PMID: 34847075 PMCID: PMC8759795 DOI: 10.1172/jci154218] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Noninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, are highly sensitive to UV light; thus, safe analyses of these processes in humans are currently beyond the reach of even the most modern ocular imaging modalities. METHODS We present a compact fluorescence scanning laser ophthalmoscope (TPEF-SLO) and spectrally resolved images of the human retina based on two-photon excitation (TPE) with near-infrared (IR) light. A custom Er:fiber laser with integrated pulse selection, along with intelligent post-processing of data, enables excitation with low laser power and precise measurement of weak signals. RESULTS We demonstrate spectrally resolved TPE fundus images of human subjects. Comparison of TPE data between human and mouse models of retinal diseases revealed similarity with mouse models that rapidly accumulate bisretinoid condensation products. Thus, visual cycle intermediates and toxic byproducts of this metabolic pathway can be measured and quantified by TPE imaging. CONCLUSION Our work establishes a TPE instrument and measurement method for noninvasive metabolic assessment of the human retina. This approach opens the possibility for monitoring eye diseases in the earliest stages before structural damage to the retina occurs. FUNDING NIH, Research to Prevent Blindness, Foundation for Polish Science, European Regional Development Fund, Polish National Agency for Academic Exchange and Polish Ministry of Science and Higher Education.
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Affiliation(s)
- Jakub Boguslawski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Grazyna Palczewska
- Department of Medical Devices, Polgenix, Inc., Cleveland, United States of America
| | - Slawomir Tomczewski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Jadwiga Milkiewicz
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Piotr Kasprzycki
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Dorota Stachowiak
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Katarzyna Komar
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Marcin J Marzejon
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Bartosz L Sikorski
- Department of Ophthalmology, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Arkadiusz Hudzikowski
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Aleksander Głuszek
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Zbigniew Łaszczych
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Karol Karnowski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Grzegorz Soboń
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Krzysztof Palczewski
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Maciej Wojtkowski
- Physical Chemistry of Biological Systems, Polish Academy of Sciences, Warsaw, Poland
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14
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Schlegel DK, Ramkumar S, von Lintig J, Neuhauss SC. Disturbed retinoid metabolism upon loss of rlbp1a impairs cone function and leads to subretinal lipid deposits and photoreceptor degeneration in the zebrafish retina. eLife 2021; 10:71473. [PMID: 34668483 PMCID: PMC8585484 DOI: 10.7554/elife.71473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 10/20/2021] [Indexed: 01/04/2023] Open
Abstract
The RLBP1 gene encodes the 36 kDa cellular retinaldehyde-binding protein, CRALBP, a soluble retinoid carrier, in the visual cycle of the eyes. Mutations in RLBP1 are associated with recessively inherited clinical phenotypes, including Bothnia dystrophy, retinitis pigmentosa, retinitis punctata albescens, fundus albipunctatus, and Newfoundland rod–cone dystrophy. However, the etiology of these retinal disorders is not well understood. Here, we generated homologous zebrafish models to bridge this knowledge gap. Duplication of the rlbp1 gene in zebrafish and cell-specific expression of the paralogs rlbp1a in the retinal pigment epithelium and rlbp1b in Müller glial cells allowed us to create intrinsically cell type-specific knockout fish lines. Using rlbp1a and rlbp1b single and double mutants, we investigated the pathological effects on visual function. Our analyses revealed that rlbp1a was essential for cone photoreceptor function and chromophore metabolism in the fish eyes. rlbp1a-mutant fish displayed reduced chromophore levels and attenuated cone photoreceptor responses to light stimuli. They accumulated 11-cis and all-trans-retinyl esters which displayed as enlarged lipid droplets in the RPE reminiscent of the subretinal yellow-white lesions in patients with RLBP1 mutations. During aging, these fish developed retinal thinning and cone and rod photoreceptor dystrophy. In contrast, rlbp1b mutants did not display impaired vision. The double mutant essentially replicated the phenotype of the rlbp1a single mutant. Together, our study showed that the rlbp1a zebrafish mutant recapitulated many features of human blinding diseases caused by RLBP1 mutations and provided novel insights into the pathways for chromophore regeneration of cone photoreceptors.
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Affiliation(s)
- Domino K Schlegel
- Department of Molecular Life Sciences, University of Zurich, Zürich, Switzerland
| | - Srinivasagan Ramkumar
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, United States
| | - Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, United States
| | - Stephan Cf Neuhauss
- Department of Molecular Life Sciences, University of Zurich, Zürich, Switzerland
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15
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Song D, Hua P, VanderBeek BL, Dunaief JL, Grunwald JE, Daniel E, Maguire MG, Martin DF, Ying GS. SYSTEMIC MEDICATION USE AND THE INCIDENCE AND GROWTH OF GEOGRAPHIC ATROPHY IN THE COMPARISON OF AGE-RELATED MACULAR DEGENERATION TREATMENTS TRIALS. Retina 2021; 41:1455-1462. [PMID: 33332813 PMCID: PMC9296271 DOI: 10.1097/iae.0000000000003075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE To determine associations of systemic medications with the incidence and growth of geographic atrophy (GA) in participants of the comparison of age-related macular degeneration treatments trials. METHODS Participants of comparison of age-related macular degeneration treatments trials with new untreated choroidal neovascularization in the study eye (one study eye per participant) were randomized to receive treatment with bevacizumab or ranibizumab. Participants were released from clinical trial treatment at 2 years and examined at approximately 5 years. Color fundus photographs and fluorescein angiograms taken at baseline, Years 1, 2, and 5 were assessed for the presence and size of GA by two masked graders. Participants were interviewed about systemic medication use at baseline. Systemic medications previously reported to be associated with age-related macular degeneration were evaluated for associations with GA incidence in study eye using univariable and multivariable Cox models and for association with the GA growth using linear mixed effects models. RESULTS In multivariable analysis of 1,011 study eyes without baseline GA, systemic medications, including cholinesterase inhibitors, angiotensin-converting enzyme inhibitors, calcium channel blockers, beta-blockers, diuretics, aspirin, steroids, statins, hormone replacement therapy, antacids, and drugs targeting G protein-coupled receptors, were not associated with GA incidence in the study eye (all adjusted hazard ratios ≤1.86, P ≥ 0.18). In multivariable analysis of 214 study eyes with longitudinal GA size measurements, calcium channel blockers were associated with a higher GA growth rate (0.40 vs. 0.30 mm/year, P = 0.02). CONCLUSION None of the systemic medications analyzed were associated with GA incidence. However, calcium channel blockers were associated with a higher growth rate of GA in the study eye.
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Affiliation(s)
- Delu Song
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Peiying Hua
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Brian L VanderBeek
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Joshua L Dunaief
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Juan E Grunwald
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Ebenezer Daniel
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Maureen G Maguire
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | | | - Gui-Shuang Ying
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
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16
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Chen W, Zhang F, Wang C, Jia M, Zhao X, Liu Z, Ge Y, Zhang Y, Zhang H. Nonlinear Photonics Using Low-Dimensional Metal-Halide Perovskites: Recent Advances and Future Challenges. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004446. [PMID: 33543536 DOI: 10.1002/adma.202004446] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/15/2020] [Indexed: 06/12/2023]
Abstract
Low-dimensional metal-halide perovskites have exhibited significantly superior nonlinear optical properties compared to traditional semiconductor counterparts, thanks to their peculiar physical and electronic structures. Their exceptional nonlinear optical characteristics make them excellent candidates for revolutionizing widespread applications. However, the research of nonlinear photonics based on low-dimensional metal-halide perovskites is in its infancy. There is a lack of comprehensive and in-depth summary of this research realm. Here, the state-of-the-art research progress related to third-and higher-order nonlinear optical properties of low-dimensional metal-halide perovskites with diverse crystal structures from 3D down to 0D, together with their practical applications, is summarized comprehensively. Critical discussions are offered on the fundamental mechanisms beneath their exceptional nonlinear optical performance from the physics viewpoint, attempting to disclose the role of intrinsic attributes (e.g., composition, bandgap, size, shape, and structure) and external modulation strategies (e.g., developing core-shell structures, transition metal ion doping, and hybridization with dielectric microspheres) in tuning the response. Additionally, their potential applications in nonlinear photonics, nonlinear optoelectronics, and biophotonics are systematically and thoroughly summed up and categorized. Lastly, insights into the current technical challenges and future research opportunities of nonlinear photonics based on low-dimensional metal-halide perovskites are provided.
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Affiliation(s)
- Weiqiang Chen
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Feng Zhang
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen, 518060, P. R. China
| | - Cong Wang
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen, 518060, P. R. China
| | - Mingshuang Jia
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Xinghang Zhao
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Zhaoran Liu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Yanqi Ge
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yupeng Zhang
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen, 518060, P. R. China
| | - Han Zhang
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen, 518060, P. R. China
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17
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Abstract
High-resolution imaging techniques capable of detecting identifiable endogenous fluorophores in the eye along with genetic testing will dramatically improve diagnostic capabilities in the ophthalmology clinic and accelerate the development of new treatments for blinding diseases. Two-photon excitation (TPE)-based imaging overcomes the filtering of ultraviolet light by the lens of the human eye and thus can be utilized to discover defects in vitamin A metabolism during the regeneration of the visual pigments required for the detection of light. Combining TPE with fluorescence lifetime imaging (FLIM) and spectral analyses offers the potential of detecting diseases of the retina at earlier stages before irreversible structural damage has occurred. The main barriers to realizing the benefits of TPE for imaging the human retina arise from concerns about the high light exposure typically needed for informative TPE imaging and the requirement to correlate the ensuing data with different states of health and disease. To overcome these hurdles, we improved TPE efficiency by controlling temporal properties of the excitation light and employed phasor analyses to FLIM and spectral data in mouse models of retinal diseases. Modeling of retinal photodamage revealed that plasma-mediated effects do not play a role and that melanin-related thermal effects are mitigated by reducing pulse repetition frequency. By using noninvasive TPE imaging we identified molecular components of individual granules in the retinal pigment epithelium and present their analytical characteristics.
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18
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von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
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Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
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19
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Wahl DJ, Ju MJ, Jian Y, Sarunic MV. Non-invasive cellular-resolution retinal imaging with two-photon excited fluorescence. BIOMEDICAL OPTICS EXPRESS 2019; 10:4859-4873. [PMID: 31565530 PMCID: PMC6757458 DOI: 10.1364/boe.10.004859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/13/2019] [Accepted: 08/13/2019] [Indexed: 05/02/2023]
Abstract
Two-photon excited fluorescence (TPEF) imaging of the retina is a developing technique that provides non-invasive compound-specific measurements from the retina. In this report, we demonstrate high-resolution TPEF imaging of the mouse retina using sensorless adaptive optics (SAO) and optical coherence tomography (OCT). A single near-infrared light source was used for simultaneous multi-modal imaging with OCT and TPEF. The image-based SAO could be performed using the en face OCT or the TPEF for aberration correction. Our results demonstrate OCT and TPEF for angiography. Also, we demonstrate non-invasive cellular-resolution imaging of fluorescently labelled cells and the Retinal Pigment Epithelium (RPE) mosaic.
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Affiliation(s)
- Daniel J. Wahl
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - Myeong Jin Ju
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - Yifan Jian
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
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20
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Abstract
In vivo imaging of mouse retinas using two-photon or confocal laser scanning fluorescence microscopy is a powerful tool for time-lapse analyses of the dynamic movements of cell populations. However, acute and reversible opacification of the crystalline lenses of mouse eyes under anesthesia decreases the visibility of the ocular fundus. Therefore, we developed a customized contact lens for preventing cataract during continuous retinal imaging in anesthetized mice. This experimental approach will aid in the elucidation of cellular and molecular dynamics in the CNS under physiological and pathological conditions.
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21
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Jayabalan GS, Bille JF, Mao XW, Gimbel HV, Rauser ME, Wenz F, Fan JT. Retinal safety evaluation of two-photon laser scanning in rats. BIOMEDICAL OPTICS EXPRESS 2019; 10:3217-3231. [PMID: 31467775 PMCID: PMC6706040 DOI: 10.1364/boe.10.003217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 05/10/2019] [Indexed: 05/03/2023]
Abstract
Safe use of retinal imaging with two-photon excitation in human eyes is crucial, as the effects of ultrashort pulsed lasers on the retina are relatively unknown. At the time of the study, the laser safety standards were inadequate due to the lack of biological data. This article addresses the feasibility of two-photon retinal imaging with respect to laser safety. In this study, rat retinas were evaluated at various laser exposure levels and with different laser parameters to determine the effects of laser-induced optical damage. The results were experimentally verified using confocal reflectance imaging, two-photon fluorescein angiography, immunohistochemistry, and correlated to the IEC 60825-1 laser safety standard.
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Affiliation(s)
- Gopal Swamy Jayabalan
- Clinic for Radiotherapy and Radiation Oncology, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
- Loma Linda University Eye Institute, Loma Linda, CA 92354, USA
| | - Josef F. Bille
- Clinic for Radiotherapy and Radiation Oncology, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Xiao Wen Mao
- Department of basic sciences, Loma Linda University, CA 92350, USA
| | | | | | - Frederik Wenz
- Clinic for Radiotherapy and Radiation Oncology, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Joseph T. Fan
- Loma Linda University Eye Institute, Loma Linda, CA 92354, USA
- Department of basic sciences, Loma Linda University, CA 92350, USA
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22
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Maeda A, Mandai M, Takahashi M. Gene and Induced Pluripotent Stem Cell Therapy for Retinal Diseases. Annu Rev Genomics Hum Genet 2019; 20:201-216. [PMID: 31018110 DOI: 10.1146/annurev-genom-083118-015043] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Given the importance of visual information to many daily activities, retinal degenerative diseases-which include both inherited conditions (such as retinitis pigmentosa) and acquired conditions (such as age-related macular degeneration)-can have a dramatic impact on human lives. The therapeutic options for these diseases remain limited. Since the discovery of the first causal gene for retinitis pigmentosa almost three decades ago, more than 250 genes have been identified, and gene therapies have been rapidly developed. Simultaneously, stem cell technologies such as induced pluripotent stem cell-based transplantation have advanced and have been applied to the treatment of retinal degenerative diseases. Here, we review recent progress in these expanding fields and discuss the potential for precision medicine in ophthalmic care.
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Affiliation(s)
- Akiko Maeda
- Laboratory for Retinal Regeneration, Center for Biosystems Dynamics Research, RIKEN, Kobe, Hyogo 650-0047, Japan;
| | - Michiko Mandai
- Laboratory for Retinal Regeneration, Center for Biosystems Dynamics Research, RIKEN, Kobe, Hyogo 650-0047, Japan;
| | - Masayo Takahashi
- Laboratory for Retinal Regeneration, Center for Biosystems Dynamics Research, RIKEN, Kobe, Hyogo 650-0047, Japan; .,Kobe City Eye Center Hospital, Kobe, Hyogo 650-0047, Japan
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23
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Rudolf M, Curcio CA, Schlötzer-Schrehardt U, Sefat AMM, Tura A, Aherrahrou Z, Brinkmann M, Grisanti S, Miura Y, Ranjbar M. Apolipoprotein A-I Mimetic Peptide L-4F Removes Bruch's Membrane Lipids in Aged Nonhuman Primates. ACTA ACUST UNITED AC 2019; 60:461-472. [DOI: 10.1167/iovs.18-25786] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Martin Rudolf
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | | | - Armin Mir Mohi Sefat
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Aysegül Tura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
| | - Zouhair Aherrahrou
- Institute for Cardiogenetics, University of Lübeck, Lübeck, Germany
- German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany
- University Heart Centre Lübeck, Lübeck, Germany
| | - Max Brinkmann
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
| | | | - Yoko Miura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
| | - Mahdy Ranjbar
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
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24
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Noninvasive Two-Photon Microscopy Imaging of Mouse Retina and Retinal Pigment Epithelium. Methods Mol Biol 2019; 1834:333-343. [PMID: 30324453 DOI: 10.1007/978-1-4939-8669-9_21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Two-photon excitation microscopy is perfectly suited for imaging deep into the retina due to its use of infrared (IR) wavelengths to excite endogenous fluorophores such as vitamin A-derived retinoids present in this tissue. Furthermore, two-photon excitation occurs only around a small focal volume, and scattered IR photons cannot excite retinal chromophores. These characteristics contribute to subcellular resolution and low noise of images obtained from deep within retinal layers. Here we describe how to customize a two-photon microscope for noninvasive imaging of the retina and retinal pigment epithelium (RPE) in the mouse eye, along with detailed instructions for mouse handling and retinal imaging, and we provide examples of mouse retinal two-photon microscopy data.
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25
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Palczewska G, Stremplewski P, Suh S, Alexander N, Salom D, Dong Z, Ruminski D, Choi EH, Sears AE, Kern TS, Wojtkowski M, Palczewski K. Two-photon imaging of the mammalian retina with ultrafast pulsing laser. JCI Insight 2018; 3:121555. [PMID: 30185665 DOI: 10.1172/jci.insight.121555] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022] Open
Abstract
Noninvasive imaging of visual system components in vivo is critical for understanding the causal mechanisms of retinal diseases and for developing therapies for their treatment. However, ultraviolet light needed to excite endogenous fluorophores that participate in metabolic processes of the retina is highly attenuated by the anterior segment of the human eye. In contrast, 2-photon excitation fluorescence imaging with pulsed infrared light overcomes this obstacle. Reducing retinal exposure to laser radiation remains a major barrier in advancing this technology to studies in humans. To increase fluorescence intensity and reduce the requisite laser power, we modulated ultrashort laser pulses with high-order dispersion compensation and applied sensorless adaptive optics and custom image recovery software and observed an over 300% increase in fluorescence of endogenous retinal fluorophores when laser pulses were shortened from 75 fs to 20 fs. No functional or structural changes to the retina were detected after exposure to 2-photon excitation imaging light with 20-fs pulses. Moreover, wide bandwidth associated with short pulses enables excitation of multiple fluorophores with different absorption spectra and thus can provide information about their relative changes and intracellular distribution. These data constitute a substantial advancement for safe 2-photon fluorescence imaging of the human eye.
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Affiliation(s)
| | - Patrycjusz Stremplewski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Susie Suh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nathan Alexander
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - David Salom
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zhiqian Dong
- Polgenix, Inc., Department of Medical Devices, Cleveland, Ohio, USA
| | - Daniel Ruminski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Elliot H Choi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Avery E Sears
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Timothy S Kern
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Maciej Wojtkowski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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Zhang L, Song W, Shao D, Zhang S, Desai M, Ness S, Roy S, Yi J. Volumetric fluorescence retinal imaging in vivo over a 30-degree field of view by oblique scanning laser ophthalmoscopy (oSLO). BIOMEDICAL OPTICS EXPRESS 2018; 9:25-40. [PMID: 29359085 PMCID: PMC5772579 DOI: 10.1364/boe.9.000025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/24/2017] [Accepted: 11/25/2017] [Indexed: 05/03/2023]
Abstract
While fluorescent contrast is widely used in ophthalmology, three-dimensional (3D) fluorescence retinal imaging over a large field of view (FOV) has been challenging. In this paper, we describe a novel oblique scanning laser ophthalmoscopy (oSLO) technique that provides 3D volumetric fluorescence retinal imaging with only one raster scan. The technique utilizes scanned oblique illumination and angled detection to obtain fluorescent cross-sectional images, analogous to optical coherence tomography (OCT) line scans (or B-scans). By breaking the coaxial optical alignment used in conventional retinal imaging modalities, depth resolution is drastically improved. To demonstrate the capability of oSLO, we have performed in vivo volumetric fluorescein angiography (FA) of the rat retina with ~25μm depth resolution and over a 30° FOV. Using depth segmentation, oSLO can obtain high contrast images of the microvasculature down to single capillaries in 3D. The multi-modal nature of oSLO also allows for seamless combination with simultaneous OCT angiography.
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Affiliation(s)
- Lei Zhang
- Department of Medicine, Boston University School of Medicine, Boston MA, 02118, USA
- These authors contributed equally to this work
| | - Weiye Song
- Department of Medicine, Boston University School of Medicine, Boston MA, 02118, USA
- These authors contributed equally to this work
| | - Di Shao
- Department of Medicine, Boston University School of Medicine, Boston MA, 02118, USA
| | - Sui Zhang
- Danna-Farber Cancer Institute, Boston MA, 02215, USA
| | - Manishi Desai
- Department of Ophthalmology, Boston University School of Medicine, Boston MA, 02118, USA
| | - Steven Ness
- Department of Ophthalmology, Boston University School of Medicine, Boston MA, 02118, USA
| | - Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston MA, 02118, USA
- Department of Ophthalmology, Boston University School of Medicine, Boston MA, 02118, USA
| | - Ji Yi
- Department of Medicine, Boston University School of Medicine, Boston MA, 02118, USA
- Center of Regenerative Medicine, Boston University, Boston, MA, 02118, USA
- Boston University Photonics Center, Boston MA, 02215, USA
- These authors contributed equally to this work
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Sharma R, Schwarz C, Hunter JJ, Palczewska G, Palczewski K, Williams DR. Formation and Clearance of All-Trans-Retinol in Rods Investigated in the Living Primate Eye With Two-Photon Ophthalmoscopy. Invest Ophthalmol Vis Sci 2017; 58:604-613. [PMID: 28129424 PMCID: PMC5283085 DOI: 10.1167/iovs.16-20061] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Two-photon excited fluorescence (TPEF) imaging has potential as a functional tool for tracking visual pigment regeneration in the living eye. Previous studies have shown that all-trans-retinol is likely the chief source of time-varying TPEF from photoreceptors. Endogenous TPEF from retinol could provide the specificity desired for tracking the visual cycle. However, in vivo characterization of native retinol kinetics is complicated by visual stimulation from the imaging beam. We have developed an imaging scheme for overcoming these challenges and monitored the formation and clearance of retinol. Methods Three macaques were imaged by using an in vivo two-photon ophthalmoscope. Endogenous TPEF was excited at 730 nm and recorded through the eye's pupil for more than 90 seconds. Two-photon excited fluorescence increased with onset of light and plateaued within 40 seconds, at which point, brief incremental stimuli were delivered at 561 nm. The responses of rods to stimulation were analyzed by using first-order kinetics. Results Two-photon excited fluorescence resulting from retinol production corresponded to the fraction of rhodopsin bleached. The photosensitivity of rhodopsin was estimated to be 6.88 ± 5.50 log scotopic troland. The rate of retinol clearance depended on intensity of incremental stimulation. Clearance was faster for stronger stimuli and time constants ranged from 50 to 300 seconds. Conclusions This study demonstrates a method for rapidly measuring the rate of clearance of retinol in vivo. Moreover, TPEF generated due to retinol can be used as a measure of rhodopsin depletion, similar to densitometry. This enhances the utility of two-photon ophthalmoscopy as a technique for evaluating the visual cycle in the living eye.
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Affiliation(s)
- Robin Sharma
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States 2Flaum Eye Institute, University of Rochester, Rochester, New York, United States 3Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- 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 2Flaum Eye Institute, University of Rochester, Rochester, New York, United States 6The Institute of Optics, University of Rochester, Rochester, New York, United States
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Chen W, Bhaumik S, Veldhuis SA, Xing G, Xu Q, Grätzel M, Mhaisalkar S, Mathews N, Sum TC. Giant five-photon absorption from multidimensional core-shell halide perovskite colloidal nanocrystals. Nat Commun 2017; 8:15198. [PMID: 28497780 PMCID: PMC5437305 DOI: 10.1038/ncomms15198] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/09/2017] [Indexed: 12/23/2022] Open
Abstract
Multiphoton absorption processes enable many technologically important applications, such as in vivo imaging, photodynamic therapy and optical limiting, and so on. Specifically, higher-order nonlinear absorption such as five-photon absorption offers significant advantages of greater spatial confinement, increased penetration depth, reduced autofluorescence, enhanced sensitivity and improved resolution over lower orders in bioimaging. Organic chromophores and conventional semiconductor nanocrystals are leaders in two-/three-photon absorption applications, but face considerable challenges from their small five-photon action cross-sections. Herein, we reveal that the family of halide perovskite colloidal nanocrystals transcend these constraints with highly efficient five-photon-excited upconversion fluorescence-unprecedented for semiconductor nanocrystals. Amazingly, their multidimensional type I (both conduction and valence band edges of core lie within bandgap of shell) core-shell (three-dimensional methylammonium lead bromide/two-dimensional octylammonium lead bromide) perovskite nanocrystals exhibit five-photon action cross-sections that are at least 9 orders larger than state-of-the-art specially designed organic molecules. Importantly, this family of halide perovskite nanocrystals may enable fresh approaches for next-generation multiphoton imaging applications.
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Affiliation(s)
- Weiqiang Chen
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, SPMS-PAP 03-05, Singapore 637371, Singapore
| | - Saikat Bhaumik
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Sjoerd A Veldhuis
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Guichuan Xing
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, SPMS-PAP 03-05, Singapore 637371, Singapore
| | - Qiang Xu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, SPMS-PAP 03-05, Singapore 637371, Singapore
| | - Michael Grätzel
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553, Singapore.,Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, Lausanne 1015, Switzerland
| | - Subodh Mhaisalkar
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553, Singapore.,School of Materials Science and Engineering, NTU, Nanyang Avenue, Singapore 639798, Singapore
| | - Nripan Mathews
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553, Singapore.,School of Materials Science and Engineering, NTU, Nanyang Avenue, Singapore 639798, Singapore
| | - Tze Chien Sum
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, SPMS-PAP 03-05, Singapore 637371, Singapore
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Schwarz C, Sharma R, Fischer WS, Chung M, Palczewska G, Palczewski K, Williams DR, Hunter JJ. Safety assessment in macaques of light exposures for functional two-photon ophthalmoscopy in humans. BIOMEDICAL OPTICS EXPRESS 2016; 7:5148-5169. [PMID: 28018732 PMCID: PMC5175559 DOI: 10.1364/boe.7.005148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/08/2016] [Accepted: 11/09/2016] [Indexed: 05/18/2023]
Abstract
Two-photon ophthalmoscopy has potential for in vivo assessment of function of normal and diseased retina. However, light safety of the sub-100 fs laser typically used is a major concern and safety standards are not well established. To test the feasibility of safe in vivo two-photon excitation fluorescence (TPEF) imaging of photoreceptors in humans, we examined the effects of ultrashort pulsed light and the required light levels with a variety of clinical and high resolution imaging methods in macaques. The only measure that revealed a significant effect due to exposure to pulsed light within existing safety standards was infrared autofluorescence (IRAF) intensity. No other structural or functional alterations were detected by other imaging techniques for any of the exposures. Photoreceptors and retinal pigment epithelium appeared normal in adaptive optics images. No effect of repeated exposures on TPEF time course was detected, suggesting that visual cycle function was maintained. If IRAF reduction is hazardous, it is the only hurdle to applying two-photon retinal imaging in humans. To date, no harmful effects of IRAF reduction have been detected.
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Affiliation(s)
- Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Robin Sharma
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | | | - Mina Chung
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
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Palczewska G, Maeda A, Golczak M, Arai E, Dong Z, Perusek L, Kevany B, Palczewski K. Receptor MER Tyrosine Kinase Proto-oncogene (MERTK) Is Not Required for Transfer of Bis-retinoids to the Retinal Pigmented Epithelium. J Biol Chem 2016; 291:26937-26949. [PMID: 27875314 DOI: 10.1074/jbc.m116.764563] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/14/2016] [Indexed: 01/08/2023] Open
Abstract
Accumulation of bis-retinoids in the retinal pigmented epithelium (RPE) is a hallmark of aging and retinal disorders such as Stargardt disease and age-related macular degeneration. These aberrant fluorescent condensation products, including di-retinoid-pyridinium-ethanolamine (A2E), are thought to be transferred to RPE cells primarily through phagocytosis of the photoreceptor outer segments. However, we observed by two-photon microscopy that mouse retinas incapable of phagocytosis due to a deficiency of the c-Mer proto-oncogene tyrosine kinase (Mertk) nonetheless contained fluorescent retinoid condensation material in their RPE. Primary RPE cells from Mertk-/- mice also accumulated fluorescent products in vitro Finally, quantification of A2E demonstrated the acquisition of retinal condensation products in Mertk-/- mouse RPE prior to retinal degeneration. In these mice, we identified activated microglial cells that likely were recruited to transport A2E-like condensation products to the RPE and dispose of the dying photoreceptor cells. These observations demonstrate a novel transport mechanism between photoreceptor cells and RPE that does not involve canonical Mertk-dependent phagocytosis.
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Affiliation(s)
| | - Akiko Maeda
- the Departments of Ophthalmology and Visual Sciences and
| | - Marcin Golczak
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Eisuke Arai
- the Departments of Ophthalmology and Visual Sciences and
| | | | | | - Brian Kevany
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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Alexander NS, Palczewska G, Stremplewski P, Wojtkowski M, Kern TS, Palczewski K. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina. BIOMEDICAL OPTICS EXPRESS 2016; 7:2671-91. [PMID: 27446697 PMCID: PMC4948621 DOI: 10.1364/boe.7.002671] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/11/2016] [Accepted: 06/11/2016] [Indexed: 05/18/2023]
Abstract
Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [Palczewska G., Nat Med.20, 785 (2014) Sharma R., Biomed. Opt. Express4, 1285 (2013)].
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Affiliation(s)
- Nathan S Alexander
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
| | | | - Patrycjusz Stremplewski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Maciej Wojtkowski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Timothy S Kern
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; Polgenix Inc., 11000 Cedar Ave, Cleveland, Ohio 44106, USA;
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Sharma R, Schwarz C, Williams DR, Palczewska G, Palczewski K, Hunter JJ. In Vivo Two-Photon Fluorescence Kinetics of Primate Rods and Cones. Invest Ophthalmol Vis Sci 2016; 57:647-57. [PMID: 26903225 PMCID: PMC4771186 DOI: 10.1167/iovs.15-17946] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Purpose The retinoid cycle maintains vision by regenerating bleached visual pigment through metabolic events, the kinetics of which have been difficult to characterize in vivo. Two-photon fluorescence excitation has been used previously to track autofluorescence directly from retinoids and pyridines in the visual cycle in mouse and frog retinas, but the mechanisms of the retinoid cycle are not well understood in primates. Methods We developed a two-photon fluorescence adaptive optics scanning light ophthalmoscope dedicated to in vivo imaging in anesthetized macaques. Using pulsed light at 730 nm, two-photon fluorescence was captured from rods and cones during light and dark adaptation through the eye's pupil. Results The fluorescence from rods and cones increased with light exposure but at different rates. During dark adaptation, autofluorescence declined, with cone autofluorescence decreasing approximately 4 times faster than from rods. Rates of autofluorescence decrease in rods and cones were approximately 4 times faster than their respective rates of photopigment regeneration. Also, subsets of sparsely distributed cones were less fluorescent than their neighbors immediately following bleach at 565 nm and they were comparable with the S cone mosaic in density and distribution. Conclusions Although other molecules could be contributing, we posit that these fluorescence changes are mediated by products of the retinoid cycle. In vivo two-photon ophthalmoscopy provides a way to monitor noninvasively stages of the retinoid cycle that were previously inaccessible in the living primate eye. This can be used to assess objectively photoreceptor function in normal and diseased retinas.
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Affiliation(s)
- Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - David R Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States
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Sears AE, Palczewski K. Lecithin:Retinol Acyltransferase: A Key Enzyme Involved in the Retinoid (visual) Cycle. Biochemistry 2016; 55:3082-91. [PMID: 27183166 DOI: 10.1021/acs.biochem.6b00319] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lecithin:retinol acyltransferase (LRAT) catalyzes the acyl transfer from the sn-1 position of phosphatidylcholine (PC) to all-trans-retinol, creating fatty acid retinyl esters (palmitoyl, stearoyl, and some unsaturated derivatives). In the eye, these retinyl esters are substrates for the 65 kDa retinoid isomerase (RPE65). LRAT is well characterized biochemically, and recent structural data from closely related family members of the NlpC/P60 superfamily and a chimeric protein have established its catalytic mechanism. Mutations in the LRAT gene are responsible for approximately 1% of reported cases of Leber congenital amaurosis (LCA). Lack of functional LRAT, expressed in the retinal pigmented epithelium (RPE), results in loss of the visual chromophore and photoreceptor degeneration. LCA is a rare hereditary retinal dystrophy with an early onset associated with mutations in one of 21 known genes. Protocols have been devised to identify therapeutics that compensate for mutations in RPE65, also associated with LCA. The same protocols can be adapted to combat dystrophies associated with LRAT. Improvement in the visual function of clinical recipients of therapy with recombinant adeno-associated virus (rAAV) vectors incorporating the RPE65 gene provides a proof of concept for LRAT, which functions in the same cell type and metabolic pathway as RPE65. In parallel, a clinical trial that employs oral 9-cis-retinyl acetate to replace the missing chromophore in RPE65 and LRAT causative disease has proven to be effective and free of adverse effects. This article summarizes the biochemistry of LRAT and examines chromophore replacement as a treatment for LCA caused by LRAT mutations.
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Affiliation(s)
- Avery E Sears
- Cleveland Center for Membrane and Structural Biology, Department of Pharmacology, School of Medicine, Case Western Reserve University , 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Krzysztof Palczewski
- Cleveland Center for Membrane and Structural Biology, Department of Pharmacology, School of Medicine, Case Western Reserve University , 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
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Sharma R, Williams DR, Palczewska G, Palczewski K, Hunter JJ. Two-Photon Autofluorescence Imaging Reveals Cellular Structures Throughout the Retina of the Living Primate Eye. Invest Ophthalmol Vis Sci 2016; 57:632-46. [PMID: 26903224 PMCID: PMC4771181 DOI: 10.1167/iovs.15-17961] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 12/30/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Although extrinsic fluorophores can be introduced to label specific cell types in the retina, endogenous fluorophores, such as NAD(P)H, FAD, collagen, and others, are present in all retinal layers. These molecules are a potential source of optical contrast and can enable noninvasive visualization of all cellular layers. We used a two-photon fluorescence adaptive optics scanning light ophthalmoscope (TPF-AOSLO) to explore the native autofluorescence of various cell classes spanning several layers in the unlabeled retina of a living primate eye. METHODS Three macaques were imaged on separate occasions using a custom TPF-AOSLO. Two-photon fluorescence was evoked by pulsed light at 730 and 920 nm excitation wavelengths, while fluorescence emission was collected in the visible range from several retinal layers and different locations. Backscattered light was recorded simultaneously in confocal modality and images were postprocessed to remove eye motion. RESULTS All retinal layers yielded two-photon signals and the heterogeneous distribution of fluorophores provided optical contrast. Several structural features were observed, such as autofluorescence from vessel walls, Müller cell processes in the nerve fibers, mosaics of cells in the ganglion cell and other nuclear layers of the inner retina, as well as photoreceptor and RPE layers in the outer retina. CONCLUSIONS This in vivo survey of two-photon autofluorescence throughout the primate retina demonstrates a wider variety of structural detail in the living eye than is available through conventional imaging methods, and broadens the use of two-photon imaging of normal and diseased eyes.
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Affiliation(s)
- Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 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
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Stremplewski P, Komar K, Palczewski K, Wojtkowski M, Palczewska G. Periscope for noninvasive two-photon imaging of murine retina in vivo. BIOMEDICAL OPTICS EXPRESS 2015; 6:3352-61. [PMID: 26417507 PMCID: PMC4574663 DOI: 10.1364/boe.6.003352] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/01/2015] [Accepted: 08/02/2015] [Indexed: 05/18/2023]
Abstract
Two-photon microscopy allows visualization of subcellular structures in the living animal retina. In previously reported experiments it was necessary to apply a contact lens to each subject. Extending this technology to larger animals would require fitting a custom contact lens to each animal and cumbersome placement of the living animal head on microscope stage. Here we demonstrate a new device, periscope, for coupling light energy into mouse eye and capturing emitted fluorescence. Using this periscope we obtained images of the RPE and their subcellular organelles, retinosomes, with larger field of view than previously reported. This periscope provides an interface with a commercial microscope, does not require contact lens and its design could be modified to image retina in larger animals.
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Affiliation(s)
- Patrycjusz Stremplewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Katarzyna Komar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
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Zhang J, Kiser PD, Badiee M, Palczewska G, Dong Z, Golczak M, Tochtrop GP, Palczewski K. Molecular pharmacodynamics of emixustat in protection against retinal degeneration. J Clin Invest 2015; 125:2781-94. [PMID: 26075817 DOI: 10.1172/jci80950] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/12/2015] [Indexed: 01/24/2023] Open
Abstract
Emixustat is a visual cycle modulator that has entered clinical trials as a treatment for age-related macular degeneration (AMD). This molecule has been proposed to inhibit the visual cycle isomerase RPE65, thereby slowing regeneration of 11-cis-retinal and reducing production of retinaldehyde condensation byproducts that may be involved in AMD pathology. Previously, we reported that all-trans-retinal (atRAL) is directly cytotoxic and that certain primary amine compounds that transiently sequester atRAL via Schiff base formation ameliorate retinal degeneration. Here, we have shown that emixustat stereoselectively inhibits RPE65 by direct active site binding. However, we detected the presence of emixustat-atRAL Schiff base conjugates, indicating that emixustat also acts as a retinal scavenger, which may contribute to its therapeutic effects. Using agents that lack either RPE65 inhibitory activity or the capacity to sequester atRAL, we assessed the relative importance of these 2 modes of action in protection against retinal phototoxicity in mice. The atRAL sequestrant QEA-B-001-NH2 conferred protection against phototoxicity without inhibiting RPE65, whereas an emixustat derivative incapable of atRAL sequestration was minimally protective, despite direct inhibition of RPE65. These data indicate that atRAL sequestration is an essential mechanism underlying the protective effects of emixustat and related compounds against retinal phototoxicity. Moreover, atRAL sequestration should be considered in the design of next-generation visual cycle modulators.
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He S, Ye C, Sun Q, Leung CK, Qu JY. Label-free nonlinear optical imaging of mouse retina. BIOMEDICAL OPTICS EXPRESS 2015; 6:1055-66. [PMID: 25798325 PMCID: PMC4361420 DOI: 10.1364/boe.6.001055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/14/2015] [Accepted: 02/16/2015] [Indexed: 05/18/2023]
Abstract
A nonlinear optical (NLO) microscopy system integrating stimulated Raman scattering (SRS), two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) was developed to image fresh mouse retinas. The morphological and functional details of various retinal layers were revealed by the endogenous NLO signals. Particularly, high resolution label-free imaging of retinal neurons and nerve fibers in the ganglion cell and nerve fiber layers was achieved by capturing endogenous SRS and TPEF signals. In addition, the spectral and temporal analysis of TPEF images allowed visualization of different fluorescent components in the retinal pigment epithelium (RPE). Fluorophores with short TPEF lifetime, such as A2E, can be differentiated from other long-lifetime components in the RPE. The NLO imaging method would provide important information for investigation of retinal ganglion cell degeneration and holds the potential to study the biochemical processes of visual cycle in the RPE.
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Affiliation(s)
- Sicong He
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,
China
- Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR,
China
- These authors contributed equally to this work
| | - Cong Ye
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong,
China
- These authors contributed equally to this work
| | - Qiqi Sun
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,
China
- Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR,
China
| | - Christopher K.S. Leung
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong,
China
| | - Jianan Y. Qu
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,
China
- Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR,
China
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Zhang N, Tsybovsky Y, Kolesnikov AV, Rozanowska M, Swider M, Schwartz SB, Stone EM, Palczewska G, Maeda A, Kefalov VJ, Jacobson SG, Cideciyan AV, Palczewski K. Protein misfolding and the pathogenesis of ABCA4-associated retinal degenerations. Hum Mol Genet 2015; 24:3220-37. [PMID: 25712131 DOI: 10.1093/hmg/ddv073] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/22/2015] [Indexed: 12/13/2022] Open
Abstract
Mutations in the ABCA4 gene are a common cause of autosomal recessive retinal degeneration. All mouse models to date are based on knockouts of Abca4, even though the disease is often caused by missense mutations such as the complex allele L541P;A1038V (PV). We now show that the PV mutation causes severe human disease whereas the V mutation alone causes mild disease. Mutant ABCA4 proteins expressed heterologously in mammalian cells retained normal cellular localization. However, basal and all-trans-retinal-stimulated ATPase activities were reduced substantially for P and PV but only mildly for V. Electron microscopy revealed marked structural changes and misfolding for the P and PV mutants but few changes for the V mutant, consistent with the disease severity difference in patients. We generated Abca4(PV/PV) knock-in mice homozygous for the complex PV allele to investigate the effects of this misfolding mutation in vivo. Mutant ABCA4 RNA levels approximated WT ABCA4 RNA levels but, surprisingly, only trace amounts of mutant ABCA4 protein were noted in the retina. RNA sequencing of WT, Abca4(-/-) and Abca4(PV/PV) mice revealed mild gene expression alterations in the retina and RPE. Similar to Abca4(-/-) mice, Abca4(PV/PV) mice showed substantial A2E and lipofuscin accumulation in their RPE cells but no retinal degeneration up to 12 months of age. Thus, rapid degradation of this large misfolded mutant protein in mouse retina caused little detectable photoreceptor degeneration. These findings suggest likely differences in the unfolded protein response between murine and human photoreceptors and support development of therapies directed at increasing this capability in patients.
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Affiliation(s)
- Ning Zhang
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
| | - Yaroslav Tsybovsky
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8096, Saint Louis, MO 63110, USA
| | - Malgorzata Rozanowska
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Malgorzata Swider
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sharon B Schwartz
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Edwin M Stone
- Department of Ophthalmology, University of Iowa Carver College of Medicine, Iowa City, IA, USA Howard Hughes Medical Institute, Iowa City, IA, USA and
| | | | - Akiko Maeda
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8096, Saint Louis, MO 63110, USA
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
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Human infrared vision is triggered by two-photon chromophore isomerization. Proc Natl Acad Sci U S A 2014; 111:E5445-54. [PMID: 25453064 DOI: 10.1073/pnas.1410162111] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Vision relies on photoactivation of visual pigments in rod and cone photoreceptor cells of the retina. The human eye structure and the absorption spectra of pigments limit our visual perception of light. Our visual perception is most responsive to stimulating light in the 400- to 720-nm (visible) range. First, we demonstrate by psychophysical experiments that humans can perceive infrared laser emission as visible light. Moreover, we show that mammalian photoreceptors can be directly activated by near infrared light with a sensitivity that paradoxically increases at wavelengths above 900 nm, and display quadratic dependence on laser power, indicating a nonlinear optical process. Biochemical experiments with rhodopsin, cone visual pigments, and a chromophore model compound 11-cis-retinyl-propylamine Schiff base demonstrate the direct isomerization of visual chromophore by a two-photon chromophore isomerization. Indeed, quantum mechanics modeling indicates the feasibility of this mechanism. Together, these findings clearly show that human visual perception of near infrared light occurs by two-photon isomerization of visual pigments.
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Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
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Babino D, Perkins BD, Kindermann A, Oberhauser V, von Lintig J. The role of 11-cis-retinyl esters in vertebrate cone vision. FASEB J 2014; 29:216-26. [PMID: 25326538 DOI: 10.1096/fj.14-261693] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A cycle of cis-to-trans isomerization of the chromophore is intrinsic to vertebrate vision where rod and cone photoreceptors mediate dim- and bright-light vision, respectively. Daylight illumination can greatly exceed the rate at which the photoproduct can be recycled back to the chromophore by the canonical visual cycle. Thus, an additional supply pathway(s) must exist to sustain cone-dependent vision. Two-photon microscopy revealed that the eyes of the zebrafish (Danio rerio) contain high levels of 11-cis-retinyl esters (11-REs) within the retinal pigment epithelium. HPLC analyses demonstrate that 11-REs are bleached by bright light and regenerated in the dark. Pharmacologic treatment with all-trans-retinylamine (Ret-NH2), a potent and specific inhibitor of the trans-to-cis reisomerization reaction of the canonical visual cycle, impeded the regeneration of 11-REs. Intervention with 11-cis-retinol restored the regeneration of 11-REs in the presence of all-trans-Ret-NH2. We used the XOPS:mCFP transgenic zebrafish line with a functional cone-only retina to directly demonstrate that this 11-RE cycle is critical to maintain vision under bright-light conditions. Thus, our analyses reveal that a dark-generated pool of 11-REs helps to supply photoreceptors with the chromophore under the varying light conditions present in natural environments.
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Affiliation(s)
- Darwin Babino
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Brian D Perkins
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA; and
| | - Aljoscha Kindermann
- Albert-Ludwigs Universität Freiburg, Institut für Biologie I, Neurobiologie und Tiephysiologie, Freiburg, Germany
| | - Vitus Oberhauser
- Albert-Ludwigs Universität Freiburg, Institut für Biologie I, Neurobiologie und Tiephysiologie, Freiburg, Germany
| | - Johannes von Lintig
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA;
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Palczewska G, Dong Z, Golczak M, Hunter JJ, Williams DR, Alexander NS, Palczewski K. Noninvasive two-photon microscopy imaging of mouse retina and retinal pigment epithelium through the pupil of the eye. Nat Med 2014; 20:785-9. [PMID: 24952647 PMCID: PMC4087080 DOI: 10.1038/nm.3590] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 11/12/2013] [Indexed: 12/11/2022]
Abstract
Two-photon excitation microscopy can image retinal molecular processes in vivo. Intrinsically fluorescent retinyl esters in subcellular structures called retinosomes are an integral part of the visual chromophore regeneration pathway. Fluorescent condensation products of all-trans-retinal accumulate in the eye with age and are also associated with age-related macular degeneration (AMD). Here, we report repetitive, dynamic imaging of these compounds in live mice through the pupil of the eye. By leveraging advanced adaptive optics, we developed a data acquisition algorithm that permitted the identification of retinosomes and condensation products in the retinal pigment epithelium by their characteristic localization, spectral properties and absence in genetically modified or drug-treated mice. This imaging approach has the potential to detect early molecular changes in retinoid metabolism that trigger light- and AMD-induced retinal defects and to assess the effectiveness of treatments for these conditions.
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Affiliation(s)
| | | | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Jennifer J Hunter
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] Flaum Eye Institute, University of Rochester, Rochester, New York, USA. [3] Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - David R Williams
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] The Institute of Optics, University of Rochester, Rochester, New York, USA
| | - Nathan S Alexander
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- 1] Polgenix, Cleveland, Ohio, USA. [2] Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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43
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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.
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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
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44
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Holz FG, Strauss EC, Schmitz-Valckenberg S, van Lookeren Campagne M. Geographic Atrophy. Ophthalmology 2014; 121:1079-91. [DOI: 10.1016/j.ophtha.2013.11.023] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 12/12/2022] Open
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45
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Zhuo S, Chen J. Stromal alterations as quantitative optical biomarkers of epithelial tumor progression. SCANNING 2014; 36:279-285. [PMID: 24347227 DOI: 10.1002/sca.21129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 10/28/2013] [Indexed: 06/03/2023]
Abstract
Stroma plays an important role during epithelial tumor progression. Probing stroma alteration may become an intrinsic indicator for evaluating epithelial tumor progression. In this review, we summarize our recent works on stromal alterations as quantitative optical biomarkers of epithelial tumor progression by use of nonlinear optical microscopy.
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Affiliation(s)
- Shuangmu Zhuo
- Institute of Laser and Optoelectronics Technology, Fujian Provincial Key Laboratory for Photonics Technology, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
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Holz FG, Schmitz-Valckenberg S, Fleckenstein M. Recent developments in the treatment of age-related macular degeneration. J Clin Invest 2014; 124:1430-8. [PMID: 24691477 PMCID: PMC3973093 DOI: 10.1172/jci71029] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Age-related macular degeneration (AMD) is a common cause of visual loss in the elderly, with increasing prevalence due to increasing life expectancy. While the introduction of anti-VEGF therapy has improved outcomes, there are still major unmet needs and gaps in the understanding of underlying biological processes. These include early, intermediate, and atrophic disease stages. Recent studies have assessed therapeutic approaches addressing various disease-associated pathways, including complement inhibitors. Drug-delivery aspects are also relevant, as many agents have to be administered repeatedly. Herein, relevant pathogenetic factors and underlying mechanisms as well as recent and potential therapeutic approaches are reviewed.
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47
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Two-photon microscopy reveals early rod photoreceptor cell damage in light-exposed mutant mice. Proc Natl Acad Sci U S A 2014; 111:E1428-37. [PMID: 24706832 DOI: 10.1073/pnas.1317986111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Atrophic age-related and juvenile macular degeneration are especially devastating due to lack of an effective cure. Two retinal cell types, photoreceptor cells and the adjacent retinal pigmented epithelium (RPE), reportedly display the earliest pathological changes. Abca4(-/-)Rdh8(-/-) mice, which mimic many features of human retinal degeneration, allowed us to determine the sequence of light-induced events leading to retinal degeneration. Using two-photon microscopy with 3D reconstruction methodology, we observed an initial strong retinoid-derived fluorescence and expansion of Abca4(-/-)Rdh8(-/-) mouse rod cell outer segments accompanied by macrophage infiltration after brief exposure of the retina to bright light. Additionally, light-dependent fluorescent compounds produced in rod outer segments were not transferred to the RPE of mice genetically defective in RPE phagocytosis. Collectively, these findings suggest that for light-induced retinopathies in mice, rod photoreceptors are the primary site of toxic retinoid accumulation and degeneration, followed by secondary changes in the RPE.
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48
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Saksens NT, Fleckenstein M, Schmitz-Valckenberg S, Holz FG, den Hollander AI, Keunen JE, Boon CJ, Hoyng CB. Macular dystrophies mimicking age-related macular degeneration. Prog Retin Eye Res 2014; 39:23-57. [PMID: 24291520 DOI: 10.1016/j.preteyeres.2013.11.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 01/30/2023]
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Affiliation(s)
| | | | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965,
United States
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50
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van Lookeren Campagne M, LeCouter J, Yaspan BL, Ye W. Mechanisms of age-related macular degeneration and therapeutic opportunities. J Pathol 2013; 232:151-64. [DOI: 10.1002/path.4266] [Citation(s) in RCA: 222] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/09/2013] [Accepted: 09/11/2013] [Indexed: 12/27/2022]
Affiliation(s)
| | - Jennifer LeCouter
- Molecular Biology Department; Genentech; South San Francisco CA 94080 USA
| | - Brian L Yaspan
- ITGR Human Genetics Department; Genentech; South San Francisco CA 94080 USA
| | - Weilan Ye
- Molecular Biology Department; Genentech; South San Francisco CA 94080 USA
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