1
|
Belashov AV, Zhikhoreva AA, Salova AV, Belyaeva TN, Litvinov IK, Kornilova ES, Semenova IV, Vasyutinskii OS. Automatic segmentation of lysosomes and analysis of intracellular pH with Radachlorin photosensitizer and FLIM. Biochem Biophys Res Commun 2024; 710:149835. [PMID: 38574457 DOI: 10.1016/j.bbrc.2024.149835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/17/2024] [Accepted: 03/25/2024] [Indexed: 04/06/2024]
Abstract
We report application of the fluorescence lifetime imaging microscopy (FLIM) for analysis of distributions of intracellular acidity using a chlorin-e6 based photosensitizer Radachlorin. An almost two-fold increase of the photosensitizer fluorescence lifetime in alkaline microenvironments as compared to acidic ones allowed for clear distinguishing between acidic and alkaline intracellular structures. Clusterization of a phasor plot calculated from fits of the FLIM raw data by two Gaussian distributions provided accurate automatic segmentation of lysosomes featuring acidic contents. The approach was validated in colocalization experiments with LysoTracker fluorescence in living cells of four established lines. The dependence of photosensitizer fluorescence lifetime on microenvironment acidity allowed for estimation of pH inside the cells, except for the nuclei, where photosensitizer does not penetrate. The developed method is promising for combined application of the photosensitizer for both photodynamic treatment and diagnostics.
Collapse
Affiliation(s)
- A V Belashov
- Ioffe Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya, St.Petersburg, 194021, Russia
| | - A A Zhikhoreva
- Ioffe Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya, St.Petersburg, 194021, Russia
| | - A V Salova
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Pr., 4, St. Petersburg, 194064, Russia
| | - T N Belyaeva
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Pr., 4, St. Petersburg, 194064, Russia
| | - I K Litvinov
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Pr., 4, St. Petersburg, 194064, Russia
| | - E S Kornilova
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Pr., 4, St. Petersburg, 194064, Russia
| | - I V Semenova
- Ioffe Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya, St.Petersburg, 194021, Russia.
| | - O S Vasyutinskii
- Ioffe Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya, St.Petersburg, 194021, Russia
| |
Collapse
|
2
|
Nguyen TD, Chen YI, Nguyen AT, Yonas S, Sripati MP, Kuo YA, Hong S, Litvinov M, He Y, Yeh HC, Grady Rylander H. Two-photon autofluorescence lifetime assay of rabbit photoreceptors and retinal pigment epithelium during light-dark visual cycles in rabbit retina. BIOMEDICAL OPTICS EXPRESS 2024; 15:3094-3111. [PMID: 38855698 PMCID: PMC11161359 DOI: 10.1364/boe.511806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 06/11/2024]
Abstract
Two-photon excited fluorescence (TPEF) is a powerful technique that enables the examination of intrinsic retinal fluorophores involved in cellular metabolism and the visual cycle. Although previous intensity-based TPEF studies in non-human primates have successfully imaged several classes of retinal cells and elucidated aspects of both rod and cone photoreceptor function, fluorescence lifetime imaging (FLIM) of the retinal cells under light-dark visual cycle has yet to be fully exploited. Here we demonstrate a FLIM assay of photoreceptors and retinal pigment epithelium (RPE) that reveals key insights into retinal physiology and adaptation. We found that photoreceptor fluorescence lifetimes increase and decrease in sync with light and dark exposure, respectively. This is likely due to changes in all-trans-retinol and all-trans-retinal levels in the outer segments, mediated by phototransduction and visual cycle activity. During light exposure, RPE fluorescence lifetime was observed to increase steadily over time, as a result of all-trans-retinol accumulation during the visual cycle and decreasing metabolism caused by the lack of normal perfusion of the sample. Our system can measure the fluorescence lifetime of intrinsic retinal fluorophores on a cellular scale, revealing differences in lifetime between retinal cell classes under different conditions of light and dark exposure.
Collapse
Affiliation(s)
- Trung Duc Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yuan-I Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Anh-Thu Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Siem Yonas
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Manasa P Sripati
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yu-An Kuo
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Soonwoo Hong
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Mitchell Litvinov
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yujie He
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
- Texas Materials Institute, University of Texas at Austin, Austin, TX, USA
| | - H Grady Rylander
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| |
Collapse
|
3
|
Gouzou D, Taimori A, Haloubi T, Finlayson N, Wang Q, Hopgood JR, Vallejo M. Applications of machine learning in time-domain fluorescence lifetime imaging: a review. Methods Appl Fluoresc 2024; 12:022001. [PMID: 38055998 PMCID: PMC10851337 DOI: 10.1088/2050-6120/ad12f7] [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: 06/30/2023] [Revised: 09/25/2023] [Accepted: 12/06/2023] [Indexed: 12/08/2023]
Abstract
Many medical imaging modalities have benefited from recent advances in Machine Learning (ML), specifically in deep learning, such as neural networks. Computers can be trained to investigate and enhance medical imaging methods without using valuable human resources. In recent years, Fluorescence Lifetime Imaging (FLIm) has received increasing attention from the ML community. FLIm goes beyond conventional spectral imaging, providing additional lifetime information, and could lead to optical histopathology supporting real-time diagnostics. However, most current studies do not use the full potential of machine/deep learning models. As a developing image modality, FLIm data are not easily obtainable, which, coupled with an absence of standardisation, is pushing back the research to develop models which could advance automated diagnosis and help promote FLIm. In this paper, we describe recent developments that improve FLIm image quality, specifically time-domain systems, and we summarise sensing, signal-to-noise analysis and the advances in registration and low-level tracking. We review the two main applications of ML for FLIm: lifetime estimation and image analysis through classification and segmentation. We suggest a course of action to improve the quality of ML studies applied to FLIm. Our final goal is to promote FLIm and attract more ML practitioners to explore the potential of lifetime imaging.
Collapse
Affiliation(s)
- Dorian Gouzou
- Dorian Gouzou and Marta Vallejo are with Institute of Signals, Sensors and Systems, School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh, EH14 4AS, United Kingdom
| | - Ali Taimori
- Tarek Haloubi, Ali Taimori, and James R. Hopgood are with Institute for Imaging, Data and Communication, School of Engineering, University of Edinburgh, Edinburgh, EH9 3FG, United Kingdom
| | - Tarek Haloubi
- Tarek Haloubi, Ali Taimori, and James R. Hopgood are with Institute for Imaging, Data and Communication, School of Engineering, University of Edinburgh, Edinburgh, EH9 3FG, United Kingdom
| | - Neil Finlayson
- Neil Finlayson is with Institute for Integrated Micro and Nano Systems, School of Engineering, University ofEdinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Qiang Wang
- Qiang Wang is with Centre for Inflammation Research, University of Edinburgh, Edinburgh, EH16 4TJ, United Kingdom
| | - James R Hopgood
- Tarek Haloubi, Ali Taimori, and James R. Hopgood are with Institute for Imaging, Data and Communication, School of Engineering, University of Edinburgh, Edinburgh, EH9 3FG, United Kingdom
| | - Marta Vallejo
- Dorian Gouzou and Marta Vallejo are with Institute of Signals, Sensors and Systems, School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh, EH14 4AS, United Kingdom
| |
Collapse
|
4
|
Nguyen TD, Chen YI, Nguyen AT, Chen LH, Yonas S, Litvinov M, He Y, Kuo YA, Hong S, Rylander HG, Yeh HC. Multiplexed imaging in live cells using pulsed interleaved excitation spectral FLIM. OPTICS EXPRESS 2024; 32:3290-3307. [PMID: 38297554 PMCID: PMC11018333 DOI: 10.1364/oe.505667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/30/2023] [Accepted: 12/30/2023] [Indexed: 02/02/2024]
Abstract
Multiplexed fluorescence detection has become increasingly important in the fields of biosensing and bioimaging. Although a variety of excitation/detection optical designs and fluorescence unmixing schemes have been proposed to allow for multiplexed imaging, rapid and reliable differentiation and quantification of multiple fluorescent species at each imaging pixel is still challenging. Here we present a pulsed interleaved excitation spectral fluorescence lifetime microscopic (PIE-sFLIM) system that can simultaneously image six fluorescent tags in live cells in a single hyperspectral snapshot. Using an alternating pulsed laser excitation scheme at two different wavelengths and a synchronized 16-channel time-resolved spectral detector, our PIE-sFLIM system can effectively excite multiple fluorophores and collect their emission over a broad spectrum for analysis. Combining our system with the advanced live-cell labeling techniques and the lifetime/spectral phasor analysis, our PIE-sFLIM approach can well unmix the fluorescence of six fluorophores acquired in a single measurement, thus improving the imaging speed in live-specimen investigation.
Collapse
Affiliation(s)
- Trung Duc Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yuan-I Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Anh-Thu Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Limin H. Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Siem Yonas
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Mitchell Litvinov
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yujie He
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yu-An Kuo
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Soonwoo Hong
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - H. Grady Rylander
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
- Texas Materials Institute, University of Texas at Austin, Austin, TX, USA
| |
Collapse
|
5
|
Bernardi M, Cardarelli F. Phasor identifier: A cloud-based analysis of phasor-FLIM data on Python notebooks. BIOPHYSICAL REPORTS 2023; 3:100135. [PMID: 38053971 PMCID: PMC10694583 DOI: 10.1016/j.bpr.2023.100135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/03/2023] [Indexed: 12/07/2023]
Abstract
This paper introduces an innovative approach utilizing Google Colaboratory for the versatile analysis of phasor fluorescence lifetime imaging microscopy (FLIM) data collected from various samples (e.g., cuvette, cells, tissues) and in various input file formats. In fact, phasor-FLIM widespread adoption has been hampered by complex instrumentation and data analysis requirements. We mean to make advanced FLIM analysis more accessible to researchers through a cloud-based solution that 1) harnesses robust computational resources, 2) eliminates hardware limitations, and 3) supports both CPU and GPU processing. We envision a paradigm shift in FLIM data accessibility and potential, aligning with the evolving field of artificial intelligence-driven FLIM analysis. This approach simplifies FLIM data handling and opens doors for diverse applications, from studying cellular metabolism to investigating drug encapsulation, benefiting researchers across multiple domains. The comparative analysis of freely distributed FLIM tools highlights the unique advantages of this approach in terms of adaptability, scalability, and open-source nature.
Collapse
|
6
|
Barroso M, Monaghan MG, Niesner R, Dmitriev RI. Probing organoid metabolism using fluorescence lifetime imaging microscopy (FLIM): The next frontier of drug discovery and disease understanding. Adv Drug Deliv Rev 2023; 201:115081. [PMID: 37647987 PMCID: PMC10543546 DOI: 10.1016/j.addr.2023.115081] [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: 02/24/2023] [Revised: 04/20/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023]
Abstract
Organoid models have been used to address important questions in developmental and cancer biology, tissue repair, advanced modelling of disease and therapies, among other bioengineering applications. Such 3D microenvironmental models can investigate the regulation of cell metabolism, and provide key insights into the mechanisms at the basis of cell growth, differentiation, communication, interactions with the environment and cell death. Their accessibility and complexity, based on 3D spatial and temporal heterogeneity, make organoids suitable for the application of novel, dynamic imaging microscopy methods, such as fluorescence lifetime imaging microscopy (FLIM) and related decay time-assessing readouts. Several biomarkers and assays have been proposed to study cell metabolism by FLIM in various organoid models. Herein, we present an expert-opinion discussion on the principles of FLIM and PLIM, instrumentation and data collection and analysis protocols, and general and emerging biosensor-based approaches, to highlight the pioneering work being performed in this field.
Collapse
Affiliation(s)
- Margarida Barroso
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY 12208, USA
| | - Michael G Monaghan
- Department of Mechanical, Manufacturing and Biomedical Engineering, Trinity College Dublin, Dublin 02, Ireland
| | - Raluca Niesner
- Dynamic and Functional In Vivo Imaging, Freie Universität Berlin and Biophysical Analytics, German Rheumatism Research Center, Berlin, Germany
| | - Ruslan I Dmitriev
- Tissue Engineering and Biomaterials Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, C. Heymanslaan 10, 9000 Ghent, Belgium; Ghent Light Microscopy Core, Ghent University, 9000 Ghent, Belgium.
| |
Collapse
|
7
|
Affiliation(s)
- Leonel Malacrida
- Departamento de Fisiopatología, Facultad de Medicina, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay.
- Advanced Bioimaging Unit, Institut Pasteur of Montevideo and Universidad de la República, Montevideo, Uruguay.
| |
Collapse
|
8
|
Marino KM, Squirrell JM, Chacko JV, Watters JW, Eliceiri KW, Ulland TK. Metabolic response of microglia to amyloid deposition during Alzheimer's disease progression in a mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.12.540407. [PMID: 37214940 PMCID: PMC10197659 DOI: 10.1101/2023.05.12.540407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Alzheimer's disease (AD) drives metabolic changes in the central nervous system (CNS). In AD microglia are activated and proliferate in response to amyloid β plaques. To further characterize the metabolic changes in microglia associated with plaque deposition in situ, we examined cortical tissue from 2, 4, and 8-month-old wild type and 5XFAD mice, a mouse model of plaque deposition. 5XFAD mice exhibited progressive microgliosis and plaque deposition as well as changes in microglial morphology and neuronal dystrophy. Multiphoton-based fluorescent lifetime imaging microscopy (FLIM) metabolic measurements showed that older mice had an increased amount of free NAD(P)H, indicative of a shift towards glycolysis. Interestingly in 5XFAD mice, we also found an abundant previously undescribed third fluorescence component that suggests an alternate NAD(P)H binding partner associated with pathology. This work demonstrates that FLIM in combination with other quantitative imaging methods, is a promising label-free tool for understanding the mechanisms of AD pathology.
Collapse
Affiliation(s)
- Kaitlyn M. Marino
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jayne M. Squirrell
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jenu V. Chacko
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jyoti W. Watters
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Kevin W. Eliceiri
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Departments of Biomedical Engineering and Medical Physics, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Tyler K. Ulland
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, 53705, USA
| |
Collapse
|
9
|
Ma Y, Huang L, Sen C, Burri S, Bruschini C, Yang X, Cameron RB, Fishbein GA, Gomperts BN, Ozcan A, Charbon E, Gao L. Light-field tomographic fluorescence lifetime imaging microscopy. RESEARCH SQUARE 2023:rs.3.rs-2883279. [PMID: 37214842 PMCID: PMC10197779 DOI: 10.21203/rs.3.rs-2883279/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fluorescence lifetime imaging microscopy (FLIM) is a powerful imaging technique that enables the visualization of biological samples at the molecular level by measuring the fluorescence decay rate of fluorescent probes. This provides critical information about molecular interactions, environmental changes, and localization within biological systems. However, creating high-resolution lifetime maps using conventional FLIM systems can be challenging, as it often requires extensive scanning that can significantly lengthen acquisition times. This issue is further compounded in three-dimensional (3D) imaging because it demands additional scanning along the depth axis. To tackle this challenge, we developed a novel computational imaging technique called light field tomographic FLIM (LIFT-FLIM). Our approach allows for the acquisition of volumetric fluorescence lifetime images in a highly data-efficient manner, significantly reducing the number of scanning steps required compared to conventional point-scanning or line-scanning FLIM imagers. Moreover, LIFT-FLIM enables the measurement of high-dimensional data using low-dimensional detectors, which are typically low-cost and feature a higher temporal bandwidth. We demonstrated LIFT-FLIM using a linear single-photon avalanche diode array on various biological systems, showcasing unparalleled single-photon detection sensitivity. Additionally, we expanded the functionality of our method to spectral FLIM and demonstrated its application in high-content multiplexed imaging of lung organoids. LIFT-FLIM has the potential to open up new avenues in both basic and translational biomedical research.
Collapse
Affiliation(s)
- Yayao Ma
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Luzhe Huang
- Department of Bioengineering, University of California, Los Angeles, CA, USA
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- California Nano Systems Institute, University of California, Los Angeles, CA, USA
| | - Chandani Sen
- UCLA Children’s Discovery and Innovation Institute, Mattel Children’s Hospital UCLA, Department of Pediatrics, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Samuel Burri
- Advanced Quantum Architecture Laboratory, Ecole Polytechnique Federale de Lausanne, Neuchatel, Switzerland
| | - Claudio Bruschini
- Advanced Quantum Architecture Laboratory, Ecole Polytechnique Federale de Lausanne, Neuchatel, Switzerland
| | - Xilin Yang
- Department of Bioengineering, University of California, Los Angeles, CA, USA
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- California Nano Systems Institute, University of California, Los Angeles, CA, USA
| | - Robert B. Cameron
- Department of Thoracic Surgery, University of California, Los Angeles, CA, USA
| | - Gregory A. Fishbein
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Brigitte N. Gomperts
- UCLA Children’s Discovery and Innovation Institute, Mattel Children’s Hospital UCLA, Department of Pediatrics, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Aydogan Ozcan
- Department of Bioengineering, University of California, Los Angeles, CA, USA
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- California Nano Systems Institute, University of California, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Edoardo Charbon
- Advanced Quantum Architecture Laboratory, Ecole Polytechnique Federale de Lausanne, Neuchatel, Switzerland
| | - Liang Gao
- Department of Bioengineering, University of California, Los Angeles, CA, USA
- California Nano Systems Institute, University of California, Los Angeles, CA, USA
| |
Collapse
|
10
|
Schweitzer D, Haueisen J, Klemm M. Suppression of natural lens fluorescence in fundus autofluorescence measurements: review of hardware solutions. BIOMEDICAL OPTICS EXPRESS 2022; 13:5151-5170. [PMID: 36425615 PMCID: PMC9664869 DOI: 10.1364/boe.462559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/25/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO), a technique for investigating metabolic changes in the eye ground, can reveal the first signs of diseases related to metabolism. The fluorescence of the natural lens overlies the fundus fluorescence. Although the influence of natural lens fluorescence can be somewhat decreased with mathematical models, excluding this influence during the measurement by using hardware enables more exact estimation of the fundus fluorescence. Here, we analyze four 1-photon excitation hardware solutions to suppress the influence of natural lens fluorescence: aperture stop separation, confocal scanning laser ophthalmoscopy, combined confocal scanning laser ophthalmoscopy and aperture stop separation, and dual point confocal scanning laser ophthalmoscopy. The effect of each principle is demonstrated in examples. The best suppression is provided by the dual point principle, realized with a confocal scanning laser ophthalmoscope. In this case, in addition to the fluorescence of the whole eye, the fluorescence of the anterior part of the eye is detected from a non-excited spot of the fundus. The intensity and time-resolved fluorescence spectral data of the fundus are derived through the subtraction of the simultaneously measured fluorescence of the excited and non-excited spots. Advantages of future 2-photon fluorescence excitation are also discussed. This study provides the first quantitative evaluation of hardware principles to suppress the fluorescence of the natural lens during measurements of fundus autofluorescence.
Collapse
Affiliation(s)
- D. Schweitzer
- Department of Ophthalmology, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - J. Haueisen
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
| | - M. Klemm
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
| |
Collapse
|
11
|
Mattana S, Dal Fovo A, Lagarto JL, Bossuto MC, Shcheslavskiy V, Fontana R, Cicchi R. Automated Phasor Segmentation of Fluorescence Lifetime Imaging Data for Discriminating Pigments and Binders Used in Artworks. Molecules 2022; 27:molecules27051475. [PMID: 35268575 PMCID: PMC8911548 DOI: 10.3390/molecules27051475] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 02/04/2023] Open
Abstract
The non-invasive analysis of fluorescence from binders and pigments employed in mixtures in artworks is a major challenge in cultural heritage science due to the broad overlapping emission of different fluorescent species causing difficulties in the data interpretation. To improve the specificity of fluorescence measurements, we went beyond steady-state fluorescence measurements by resolving the fluorescence decay dynamics of the emitting species through time-resolved fluorescence imaging (TRFI). In particular, we acquired the fluorescence decay features of different pigments and binders using a portable and compact fibre-based imaging setup. Fluorescence time-resolved data were analysed using the phasor method followed by a Gaussian mixture model (GMM) to automatically identify the populations of fluorescent species within the fluorescence decay maps. Our results demonstrate that this approach allows distinguishing different binders when mixed with the same pigment as well as discriminating different pigments dispersed in a common binder. The results obtained could establish a framework for the analysis of a broader range of pigments and binders to be then extended to several other materials used in art production. The obtained results, together with the compactness and portability of the instrument, pave the way for future in situ applications of the technology on paintings.
Collapse
Affiliation(s)
- Sara Mattana
- National Institute of Optics—National Research Council (CNR-INO), Largo E. Fermi 6, 50125 Florence, Italy; (S.M.); (A.D.F.); (R.F.); (R.C.)
| | - Alice Dal Fovo
- National Institute of Optics—National Research Council (CNR-INO), Largo E. Fermi 6, 50125 Florence, Italy; (S.M.); (A.D.F.); (R.F.); (R.C.)
| | - João Luís Lagarto
- Biophotonics Platform, Champalimaud Clinical Centre, Champalimaud Foundation, Av. Brasilia, 1400-038 Lisbon, Portugal
- Correspondence:
| | - Maria Chiara Bossuto
- Department of Physics, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Italy;
| | - Vladislav Shcheslavskiy
- Becker & Hickl GmbH, Nunsdorfer Ring 7-9, 12277 Berlin, Germany;
- Privolzhskiy Research Medical University, 603005 Nizhny Novgorod, Russia
| | - Raffaella Fontana
- National Institute of Optics—National Research Council (CNR-INO), Largo E. Fermi 6, 50125 Florence, Italy; (S.M.); (A.D.F.); (R.F.); (R.C.)
| | - Riccardo Cicchi
- National Institute of Optics—National Research Council (CNR-INO), Largo E. Fermi 6, 50125 Florence, Italy; (S.M.); (A.D.F.); (R.F.); (R.C.)
- European Laboratory for Non-Linear Spectroscopy (LENS), Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
| |
Collapse
|
12
|
Linear Combination Properties of the Phasor Space in Fluorescence Imaging. SENSORS 2022; 22:s22030999. [PMID: 35161742 PMCID: PMC8840623 DOI: 10.3390/s22030999] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/15/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022]
Abstract
The phasor approach to fluorescence lifetime imaging, and more recently hyperspectral fluorescence imaging, has increased the use of these techniques, and improved the ease and intuitiveness of the data analysis. The fit-free nature of the phasor plots increases the speed of the analysis and reduces the dimensionality, optimization of data handling and storage. The reciprocity principle between the real and imaginary space-where the phasor and the pixel that the phasor originated from are linked and can be converted from one another-has helped the expansion of this method. The phasor coordinates calculated from a pixel, where multiple fluorescent species are present, depends on the phasor positions of those components. The relative positions are governed by the linear combination properties of the phasor space. According to this principle, the phasor position of a pixel with multiple components lies inside the polygon whose vertices are occupied by the phasor positions of these individual components and the distance between the image phasor to any of the vertices is inversely proportional to the fractional intensity contribution of that component to the total fluorescence from that image pixel. The higher the fractional intensity contribution of a vertex, the closer is the resultant phasor. The linear additivity in the phasor space can be exploited to obtain the fractional intensity contribution from multiple species and quantify their contribution. This review details the various mathematical models that can be used to obtain two/three/four components from phasor space with known phasor signatures and then how to obtain both the fractional intensities and phasor positions without any prior knowledge of either, assuming they are mono-exponential in nature. We note that other than for blind components, there are no restrictions on the type of the decay or their phasor positions for linear combinations to be valid-and they are applicable to complicated fluorescence lifetime decays from components with intensity decays described by multi-exponentials.
Collapse
|
13
|
Vu T, Vallmitjana A, Gu J, La K, Xu Q, Flores J, Zimak J, Shiu J, Hosohama L, Wu J, Douglas C, Waterman ML, Ganesan A, Hedde PN, Gratton E, Zhao W. Spatial transcriptomics using combinatorial fluorescence spectral and lifetime encoding, imaging and analysis. Nat Commun 2022; 13:169. [PMID: 35013281 PMCID: PMC8748653 DOI: 10.1038/s41467-021-27798-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 12/15/2021] [Indexed: 12/14/2022] Open
Abstract
Multiplexed mRNA profiling in the spatial context provides new information enabling basic research and clinical applications. Unfortunately, existing spatial transcriptomics methods are limited due to either low multiplexing or complexity. Here, we introduce a spatialomics technology, termed Multi Omic Single-scan Assay with Integrated Combinatorial Analysis (MOSAICA), that integrates in situ labeling of mRNA and protein markers in cells or tissues with combinatorial fluorescence spectral and lifetime encoded probes, spectral and time-resolved fluorescence imaging, and machine learning-based decoding. We demonstrate MOSAICA's multiplexing scalability in detecting 10-plex targets in fixed colorectal cancer cells using combinatorial labeling of five fluorophores with facile error-detection and removal of autofluorescence. MOSAICA's analysis is strongly correlated with sequencing data (Pearson's r = 0.96) and was further benchmarked using RNAscopeTM and LGC StellarisTM. We further apply MOSAICA for multiplexed analysis of clinical melanoma Formalin-Fixed Paraffin-Embedded (FFPE) tissues. We finally demonstrate simultaneous co-detection of protein and mRNA in cancer cells.
Collapse
Affiliation(s)
- Tam Vu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, 92697, USA
| | - Alexander Vallmitjana
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, CA, 92697, USA
| | - Joshua Gu
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, 92697, USA
| | - Kieu La
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA
| | - Qi Xu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA
| | - Jesus Flores
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, 92697, USA
- CIRM Stem Cell Research Biotechnology Training Program at California State University, Long Beach, Long Beach, CA, 90840, USA
| | - Jan Zimak
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, 92697, USA
| | - Jessica Shiu
- Department of Dermatology, University of California, Irvine, Irvine, CA, 92697, USA
| | - Linzi Hosohama
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, 92697, USA
| | - Jie Wu
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, 92697, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA, 92697, USA
| | - Christopher Douglas
- Department of Pathology & Laboratory Medicine, University of California, Irvine, Irvine, CA, 92617, USA
| | - Marian L Waterman
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, 92697, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA, 92697, USA
| | - Anand Ganesan
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Dermatology, University of California, Irvine, Irvine, CA, 92697, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA, 92697, USA
| | - Per Niklas Hedde
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, 92697, USA
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, Irvine, CA, 92697, USA
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA.
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, CA, 92697, USA.
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, Irvine, CA, 92697, USA.
| | - Weian Zhao
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697, USA.
- Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, 92697, USA.
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, 92697, USA.
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, 92697, USA.
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA, 92697, USA.
| |
Collapse
|