PurposeThe aim of this study was to develop and characterize a novel peptide imaging agent for noninvasive near-infrared fluorescence imaging of protein transport by the lymphatics. An imaging agent consisting of a cyclic albumin-binding domain (cABD) peptide, with sequence, Arg-Leu-Ile-Glu-Asp-Ile-Cys-Leu-Pro-Arg-Trp-Gly-Cys-Leu-Trp-Glu-Asp-Asp-Lys, was conjugated to a near-infrared fluorophore, IRDye800CW, allowing for enhanced vascular uptake, retention, and fluorescence imaging.ProcedureCharacterization of the cABD-IRDye800 peptide conjugate was performed using fluorescence spectroscopy to assess optical properties and SDS-PAGE and Biacore binding assays to determine binding affinity and specificity. Fluorescence imaging of normal C57BL/6 mice was conducted to monitor lymphatic uptake and retention.ResultscABD-IRDye800 exhibited approximately six times greater fluorescent yield and greater stability than indocyanine green, an agent previously used in humans to image lymphatic vasculature. The agent exhibited affinity for albumin with IC50 and Kd in the nanomolar range and demonstrated superior retention characteristics within mouse lymphatics when compared with IRDye800CW.ConclusionscABD-IRDye800 has utility for assessing lymphatic function in mouse models of human lymphatic disease and the potential for use in clinical diagnostic imaging of the lymphatic vasculature.Electronic supplementary materialThe online version of this article (doi:10.1007/s11307-011-0499-x) contains supplementary material, which is available to authorized users.
Background: Absorbance of near-infrared (600-800 nm) light by the tissue components water, melanin, and hemoglobin is minimal. This property allows the use of near-infrared-emitting fluorophores for noninvasive, in vivo, real-time imaging of tissue, without the interference of autofluorescence experienced with imaging in other wavelength ranges. Near-infrared (NIR) fluorescence imaging has been used to noninvasively image lymphatic architecture and pumping function in animals, as well as in humans. The effects of different doses of a NIR dye, indocyanine green (ICG), on lymphatic function have been questioned. This study aims to address these concerns in the context of a mouse inguinal-to-axillary lymphatic imaging model. Methods and Results: We measured lymph propulsive velocity and frequency using an imaging system composed of a laser diode for excitation of the dye, an image intensifier, and an intensified charge-coupled device (ICCD) camera to capture real-time images. At 0.32, 0.645, and 1.3 mM ICG, no significant differences in lymphatic propulsive velocity or frequency were observed. Additionally, the use of other NIR imaging agents did not result in significant differences. Conclusions: The use of different concentrations of ICG and the use of other near-infrared fluorophores for optical imaging of lymphatics does not significantly affect lymphatic propulsive velocity or frequency.
The effects of inflammation on the lymphatic system are largely unknown, with conflicting reports of enhanced or decreased activity. We imaged murine lymphatic vessels and function using a custom-designed ICCD camera/low-level laser system and an intradermally injected fluorescent dye, indocyanine green, which is rapidly taken up by the lymphatic vasculature. Mice injected with LPS exhibited a drastic, systemic decrease in collecting vessel lymphatic propulsive flow velocity and frequency at 4-24 hours after the inflammatory insult, gradually increasing to normal values by 7 days post-inflammation. IL-6, TNF-alpha, MCP-1, MCP-5, RANTES, and IL-10 levels were increased in plasma at 4-24 hours. Draining lymph nodes retained ICG at 6-7 days post-inflammation, perhaps indicating restriction of afferent and/or efferent lymphatic vessels. This system for non-invasive imaging of the lymphatic system under inflammatory conditions may allow insights into mechanisms of inflammation and its resolution.
Lymphedema (LE) is a disabling condition resulting from genetic predisposition, cancer treatments involving lymph nodes, or nematode infection. Obtaining in vivo images of healthy and diseased lymphatic vessels and lymph nodes, until now, has required using radionucleotide imaging agents, and has resulted in grainy, nondistinct images. We used a custom-designed ICCD camera system and low-level laser excitation of intradermally injected fluorescent dye to obtain live, non-invasive images of lymphatic vessel architecture and function in humans with and without lymphedema. This technique has provided exquisite images and movies of lymphatic abnormalities such as tortuous vessels and patchy “starry night” areas, as well as the ability to measure lymph propulsive velocity and frequency. This non-invasive, live, in vivo imaging of the human lymphatic system in health and disease may provide opportunities to diagnose lymphatic disorders, direct cancer resections, and evaluate therapies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.