Table 2.
Nanoscale contrast agents used for imaging engineered vasculature.
| Imaging modality | Contrast agent | Outcome | Reference |
|---|---|---|---|
| In situ labeling and vascular imaging | |||
| Magnetic resonance imaging | Gadolinium immobilized liposomes (75.9nm) | Increased contrast and larger field of view for imaging small blood vessels | Howles et al. [47] |
| Photoacoustic imaging | Hollow gold nanospheres (40 nm) | Enhanced vascular contrast and visualization of vessels as small as ~100nm in diameter | Lu et al. [48] |
| Intravital imaging | RGD-QDs (6–8 nm) | QDs specifically targeted newly formed vessels expressing αvβ3 integrins | Smith et al. [50] |
| Magnetic resonance imaging | Perfluorocarbon NPs (<300 nm) | NPs targeted αvβ3 integrins and enhanced angiogenesis for L-arginine treated animals | Winter et al. [49] |
| Cell pre-labeling and imaging | |||
| Fluorescent microscopy | QDs | QDs detectable up to 2 days or 14 days in vivo | Lin et al. [2] |
| CdSe/ZnS QDs (10–15 nm) | Dose-dependent cytotoxicity effects on MSCs | Muller-Borer et al. [53] | |
| Photoacoustic imaging | Gold NPs (20–60 nm) | Gold NPs of various sizes and surface coatings did not compromise MSC function | Ricles et al. [3] |
| Gold NPs (20 nm) | In vivo imaging of MSCs up to day 10 | Nam et al. [4] | |
| Multi-photon photoluminescence imaging | Gold NPs (10 nm) | ESC function not compromised and cells were imaged in vitro | Nagesha et al. [63] |
| Magnetic resonance imaging | SPIO | NP labeling had no effect on cell function, and the cells could be tracked in vivo up to 18 weeks | Guzman et al. [66] |
| Carboxy-dextran-coated iron oxide NPs | MSCs were in the renal cortex up to three days and renal function was significantly improved | Lange et al. [5] | |
| Poly-L-lysine coated magnetic NPs | MSCs were visible in MI model up to 1 week, but there was significant decrease in signal after 3 weeks | Kraitchman et al. [67] | |
| Magnetic resonance and fluorescence imaging | SPIO@SiO2(FITC) | In vivo imaging of MSCs labeled with FITC-incorporated silica-coated core-shell SPIO NPs | Lu et al. [68] |
| Magnetic resonance imaging and X-ray | Fe3O4/gold nanohybrids (35 nm) | Nanohybrids did not alter cell function and could be imaged with MRI and CT with enhanced contrast | Narayanan et al. [69] |
| Positron emission tomography and magnetic resonance imaging | SPIO@SiO2 | High uptake efficiency of SPIO core NPs in MSCs and no cytotoxic effects | Patel et al. [70] |