High-resolution contrast-enhanced optical coherence tomography in mice retinae.
Optical coherence tomography (OCT) is a noninvasive interferometric imaging modality providing anatomical information at depths of millimeters and a resolution of micrometers. Conventional OCT images limit our knowledge to anatomical structures alone, without any contrast enhancement. Therefore, here we have, for the first time, optimized an OCT-based contrast-enhanced imaging system for imaging single cells and blood vessels in vivo inside the living mouse retina at subnanomolar sensitivity. We used bioconjugated gold nanorods (GNRs) as exogenous OCT contrast agents. Specifically, we used anti-mouse CD45 coated GNRs to label mouse leukocytes and mPEG-coated GNRs to determine sensitivity of GNR detection in vivo inside mice retinae. We corroborated OCT observations with hyperspectral dark-field microscopy of formalin-fixed histological sections. Our results show that mouse leukocytes that otherwise do not produce OCT contrast can be labeled with GNRs leading to significant OCT intensity equivalent to a 0.5 nM GNR solution. Furthermore, GNRs injected intravenously can be detected inside retinal blood vessels at a sensitivity of ∼0.5  nM, and GNR-labeled cells injected intravenously can be detected inside retinal capillaries by enhanced OCT contrast. We envision the unprecedented resolution and sensitivity of functionalized GNRs coupled with OCT to be adopted for longitudinal studies of retinal disorders.
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United StatesbStanford University, Molecular Imaging Program at Stanford, 299 Campus Drive, Stanford, California 94305, United States.
Debasish
D
Sen
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United StatescStanford University, Biophysics Program, 299 Campus Drive, Stanford, California 94305, United StatesdStanford University, Department of Elec.
Elliott D
ED
SoRelle
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United StatesbStanford University, Molecular Imaging Program at Stanford, 299 Campus Drive, Stanford, California 94305, United StatesdStanford University.
Orly
O
Liba
Stanford University, Department of Ophthalmology, 300 Pasteur Drive, Palo Alto, California 94304, United States.
Roopa
R
Dalal
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United States.
Yannis M
YM
Paulus
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United States.
Tae-Wan
TW
Kim
Stanford University, Bio-X Program, 299 Campus Drive, Stanford, California, 94305, United StatesgStanford University, Department of Ophthalmology, Stanford Byers Eye Institute, 2452 Watson Court, Palo Alto, California 94303, United States.
Darius M
DM
Moshfeghi
Stanford University, Department of Structural Biology, 299 Campus Drive, Stanford, California 94305, United StatesbStanford University, Molecular Imaging Program at Stanford, 299 Campus Drive, Stanford, California 94305, United StatescStanford University.
Adam
A
de la Zerda
D000818:Animals; D003287:Contrast Media / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007368:Interferometry; D051379:Mice; D043942:Nanotubes / Q000737:chemistry*; D012160:Retina / Q000000981:diagnostic imaging*; D041623:Tomography, Optical Coherence
D003287:Contrast Media; D006046:Gold