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Tun SBB, Barathi VA. Akimba Proliferative Diabetic Retinopathy Model: Understanding Molecular Mechanism and Drug Screening for the Progression of Diabetic Retinopathy. Methods Mol Biol 2023; 2678:13-26. [PMID: 37326702 DOI: 10.1007/978-1-0716-3255-0_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
As the prevalence of diabetes has reached epidemic proportions worldwide, diabetic retinopathy incidence is increasing rapidly. An advanced diabetic retinopathy (DR) stage can lead to a sight-threatening form. There is growing evidence showing diabetes causes a range of metabolic changes that subsequently lead to pathological modifications in the retina and retinal blood vessels. To understand the complex mechanism of the pathophysiology of DR, a precise model is not readily available. By crossbreeding the Akita and Kimba strains, a suitable proliferative DR model was acquired. This new Akimba strain manifests marked hyperglycemia and vascular changes, which resemble the early and advanced stage of DR.Here, we describe the breeding method, colony screening for experiments, and imaging techniques widely used to investigate the DR progression in this model. We elaborate step-by-step protocols to set up and perform fundus, fluorescein angiography, optical coherence tomography, and optical coherence tomography-angiogram to study retinal structural changes and vascular abnormalities. In addition, we show a method to label the leukocytes with fluorescence and laser speckle flowgraphy to examine the inflammation in the retina and retinal vessel blood flow speed, respectively. Lastly, we describe electroretinogram to evaluate the functional aspect of the DR transformations.
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Affiliation(s)
- Sai Bo Bo Tun
- Translational Pre-Clinical Model Platform, Singapore Eye Research Institute, Singapore, Singapore
- Karolinska Institutet, Stockholm, Sweden
| | - Veluchamy Amutha Barathi
- Translational Pre-Clinical Model Platform, Singapore Eye Research Institute, Singapore, Singapore.
- ACP in Ophthalmology & Visual Sciences, DUKE-NUS Graduate Medical School, Singapore, Singapore.
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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Le AV, Fenech M. Image-Based Experimental Measurement Techniques to Characterize Velocity Fields in Blood Microflows. Front Physiol 2022; 13:886675. [PMID: 35574441 PMCID: PMC9099138 DOI: 10.3389/fphys.2022.886675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Predicting blood microflow in both simple and complex geometries is challenging because of the composition and behavior of the blood at microscale. However, characterization of the velocity in microchannels is the key for gaining insights into cellular interactions at the microscale, mechanisms of diseases, and efficacy of therapeutic solutions. Image-based measurement techniques are a subset of methods for measuring the local flow velocity that typically utilize tracer particles for flow visualization. In the most basic form, a high-speed camera and microscope setup are the only requirements for data acquisition; however, the development of image processing algorithms and equipment has made current image-based techniques more sophisticated. This mini review aims to provide a succinct and accessible overview of image-based experimental measurement techniques to characterize the velocity field of blood microflow. The following techniques are introduced: cell tracking velocimetry, kymographs, micro-particle velocimetry, and dual-slit photometry as entry techniques for measuring various velocity fields either in vivo or in vitro.
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Affiliation(s)
- Andy Vinh Le
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON, Canada
- Centre de Biochimie Structurale, CNRS UMR 5048—INSERM UMR 1054, University of Montpellier, Montpellier, France
| | - Marianne Fenech
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON, Canada
- *Correspondence: Marianne Fenech,
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Dybala MP, Hara M. In Vivo and In Situ Approach to Study Islet Microcirculation: A Mini-Review. Front Endocrinol (Lausanne) 2021; 12:602620. [PMID: 34040578 PMCID: PMC8142941 DOI: 10.3389/fendo.2021.602620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 04/26/2021] [Indexed: 11/28/2022] Open
Abstract
The pancreas is regarded as consisting of two separate organ systems, the endocrine and exocrine pancreas. While treatment of a disease with either an endocrine or exocrine pathogenesis may affect the function of the entire pancreas, the pancreatic diseases have been treated by clinicians in different medical disciplines, including endocrinologists and gastroenterologists. Islet microcirculation has long been considered to be regulated independently from that of the exocrine pancreas. A new model proposes that pancreatic islet blood flow is integrated with the surrounding exocrine capillary network. This recent model may provide revived or contrasting hypotheses to test, since the pancreatic microcirculation has critical implications for the regulation of islet hormones as well as acinar pancreas functions. In this mini-review, practical applications of in vivo and in situ studies of islet microcirculation are described with a specific emphasis on large-scale data analysis to ensure sufficient sample size accounting for known islet heterogeneity. For in vivo small animal studies, intravital microscopy based on two-photon excitation microscopes is a powerful tool that enables capturing the flow direction and speed of individual fluorescent-labeled red blood cells. Complementarily, for structural analysis of blood vessels, the recent technical advancements of confocal microscopy and tissue clearing have enabled us to image the three-dimensional network structure in thick tissue slices.
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Affiliation(s)
| | - Manami Hara
- Department of Medicine, The University of Chicago, Chicago, IL, United States
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Kumar S, Jiang D, Sun B, Seeley KV, Engle JW, Sia Z, He X, Neelamegham S, Cai W, Lovell JF. Labeling of Erythrocytes by Porphyrin-Phospholipid. ADVANCED NANOBIOMED RESEARCH 2020; 1. [PMID: 34212160 DOI: 10.1002/anbr.202000013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
A method is developed for membrane labeling of erythrocytes with porphyrin-phospholipid (PoP). To generate a concentrated PoP solution for labeling human red blood cells (RBCs), various surfactants and solvents are screened to identify conditions that avoid hemolysis, while minimizing non-specific PoP co-precipitation with RBCs in the pellet during centrifugation washes. Cholate, Tween 80 and Tween 40 are identified as useful surfactants for this purpose. When labeled RBCs are mixed with unlabeled ones, substantial non-specific PoP exchange is observed. Egg-yolk lecithin is included in a washing buffer to remove loosely bound PoP and reduce PoP exchange with unlabeled erythrocytes, based on flow cytometry and photodynamic hemolysis assays. Murine RBCs that are labeled with 64Cu-chelated PoP displayed altered biodistribution with longer blood circulation relative to directly administered 64Cu-chelated PoP.
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Affiliation(s)
- Sunanda Kumar
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Dawei Jiang
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Boyang Sun
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Kaelyn V Seeley
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Jonathan W Engle
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Zachary Sia
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Xuedan He
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Sriram Neelamegham
- Department of Chemical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Weibo Cai
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Jonathan F Lovell
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
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Tang JC, Partono A, Anvari B. Near-Infrared-Fluorescent Erythrocyte-Mimicking Particles: Physical and Optical Characteristics. IEEE Trans Biomed Eng 2019; 66:1034-1044. [PMID: 30130175 PMCID: PMC6382600 DOI: 10.1109/tbme.2018.2866368] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Exogenous fluorescent materials activated by near-infrared (NIR) light can offer deep optical imaging with subcellular resolution, and enhanced image contrast. We have engineered NIR particles by doping hemoglobin-depleted erythrocyte ghosts (EGs) with indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micrometer to nanometer scale, thereby, providing a capability for broad NIR biomedical imaging applications. Herein, we investigate the effects of ICG concentration on key material properties of micrometer-sized NETs, and nanometer-sized NETs fabricated by either sonication or mechanical extrusion of EGs. The zeta potentials of NETs do not vary significantly with ICG concentration, suggesting that ICG is encapsulated within NETs regardless of particle size or ICG concentration. Loading efficiency of ICG into the NETs monotonically decreases with increasing values of ICG concentration. Based on quantitative analyses of the fluorescence emission spectra of the NETs, we determine that 20 μM ICG utilized during fabrication of NETs presents an optimal concentration that maximizes the integrated fluorescence emission for micrometer- and nanometer-sized NETs. Encapsulation of the ICG in these constructs also enhances the fluorescence stability and quantum yield of ICG. These results guide the engineering of NETs with maximal NIR emission for imaging applications such as fluorescence-guided tumor resection and real-time angiography.
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Agrawal R, Tun SBB, Balne PK, Zhu HY, Khandelwal N, Barathi VA. Fluorescein Labeled Leukocytes for in vivo Imaging of Retinal Vascular Inflammation and Infiltrating Leukocytes in Laser-Induced Choroidal Neovascularization Model. Ocul Immunol Inflamm 2018; 28:7-13. [PMID: 29470933 DOI: 10.1080/09273948.2018.1429637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Purpose: To study the effect of anti-VEGF treatment on retinal inflammation in a laser-induced CNV rodent model.Methods: Leukocytes labeled with 1% sodium fluorescein were injected into the laser-induced CNV (wild type C57BL/6) mice at days 4 (baseline), 7, 14, and 19. At baseline intravitreally 3 mice received 1× PBS, and 3 mice received anti-VEGF. FFA, OCT, and SLO were performed at each time point to assess the CNV pathophysiology and inflammatory response.Results: Fluorescein leakage, SRF, and leukocyte infiltration were observed at baseline in both the groups before injection. From days 7 to 19, leukocyte infiltration and SRF were noted in the 1× PBS group, but limited or no SRF and leukocyte infiltration was observed in the anti-VEGF group.Conclusions: Leukocyte infiltration was established as an in vivo imaging inflammatory marker and along with FFA and OCT showed response to anti-VEGF therapy in laser-induced CNV model.
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Affiliation(s)
- Rupesh Agrawal
- Translational Preclinical Model Platform, Singapore Eye Research Institute, Singapore.,National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Sai Bo Bo Tun
- Translational Preclinical Model Platform, Singapore Eye Research Institute, Singapore
| | - Praveen Kumar Balne
- Translational Preclinical Model Platform, Singapore Eye Research Institute, Singapore
| | - Hong-Yuan Zhu
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore
| | - Neha Khandelwal
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore
| | - Veluchamy A Barathi
- Translational Preclinical Model Platform, Singapore Eye Research Institute, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Ophthalmology Academic Clinical Research Program, DUKE-NUS Graduate Medical School, Singapore
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