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A. Jayagopal, P. K. Russ, F. R. Haselton; Quantum Dot-Mediated Multispectral in vivo Imaging of Endotoxin-Induced Uveitis in Retina. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4950.
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© ARVO (1962-2015); The Authors (2016-present)
In vivo molecular imaging techniques facilitate in-depth studies which elucidate biological processes and the key mechanisms and mediators of disease. Quantum dots are a class of nanoparticles which have high photostabilities and fluorescence intensities, are amenable to the bioconjugation of bioactive ligands, and have size-tunable emission profiles which enable the multiplexed detection of several biomolecules simultaneously. In this study, we applied our multispectral quantum dot-based retinal imaging system toward the study of leukocyte trafficking in a rat model of endotoxin-induced uveitis (EIU).
The retina was used to non-invasively probe inflammatory activity in the circulation using spectrally-distinct quantum dot-antibody bioconjugates targeted toward leukocyte subtypes. The probes featured site-specific antibody crosslinking steps to maintain native antibody affinity, Fc fragment blockade and polyethylene glycol surface engineering steps to reduce immune-mediated clearance and nonspecific binding. Specificity of probes toward leukocyte cell surface targets and their effect on cell viability were quantified using flow cytometry. EIU rats and untreated controls were systemically-injected with the bioconjugates, and observed for one hour intervals up to 24 hours post-injection to investigate leukocyte subtype recruitment, activation state, and motility parameters such as velocity and adhesions in capillaries and major vessels in retinal vasculature.
Quantum dot-antibody constructs were shown to be specific for leukocyte targets with negligible nonspecific binding. We report significantly-elevated fluorescent leukocyte accumulation in the retinal vasculature in EIU rats relative to controls. It was possible to measure leukocyte velocities, and activation state of leukocytes could be monitored by determination of relative fluorescence intensities of labeled cells. Furthermore, color-coded leukocyte subtypes could be differentiated.
Quantum dot probes are suitable for the multiplexed analysis of cells and/or biomolecules in the retinal vasculature. The retina provides an optically-accessbile, non-invasive imaging window to probe inflammation, and quantum dot probes are highly-specific for their cellular targets, enabling high-sensitivity, high-resolution imaging applications which harness their superior optical properties.
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