The most used
class of MRI probes for cellular imaging is represented by iron oxide
nanoparticles (IONPs). Even if they succeeded at both preclinical and clinical
levels in many cases, the negative constrast they produce as T2 or T2*
contrast agents may be a drawback, making an unambiguous detection of the
labelled cells very challenging especially in organs with an intrinsically low
MRI signal (e.g. lung, bones) or in the presence of haemorrhages. In addition,
the contrast generated by IONP-labelled cells is linearly correlated to the
cells number only at low iron concentrations.
A new emerging
approach for cellular MRI is based on agents containing fluorine (19F,
100% natural abundance). 19F-based MRI has gained huge attention in
the last 20 years, owing to the possibility to obtain quantitative information
in a diagnostic MR protocol because of the absence of background signal allows
specific and selective detection of the administrated 19F-containing
probes in vivo. Moreover, the
chemical shift of 19F is spread out over a wide range, thus allowing
the selective observation of different agents present in the same anatomical
district. The 19F-containing contrast agents studied so far are
mostly nanosized.
Because of their
high payload of 19F atoms, perfluorocarbons (PFCs), under the form of
nanoemulsions, are the most frequently used 19F-MRI contrast agents for
biological applications. Recent studies have demonstrated the potential of PFCs
to label and image cells (mostly phagocytic) either in vitro or in vivo
and have demonstratedthe the potential
of cellular 19F-MRI, especially for quantifying the number of labelled cells.
Menchise,
V., Digilio, G., Gianolio,
E., Catanzaro, V., Carrera, C.,
Aime, S. In Vivo Labeling of B16 Melanoma Tumor Xenograft with a Thiol-Reactive
Gadolinium Based MRI Contrast Agent Molecular Pharmaceutics (2011)
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Catanzaro, C., Gringeri, C. V.,
Menchise, V., Padovan, S., Boffa, C., Dastrù, W., Chaabane, L., Digilio, G.,
Aime, S. A R2p/R1p ratiometric procedure to assess Matrix Metalloproteinase-2 activity
by Magnetic Resonance Imaging. Angew. Chem. Int. (2013), 52, 3926–3930. (DOI:
10.1002/anie.201209286).
Figueiredo, S., Cutrin, J.C., Rizzitelli, S., De
Luca, E., Moreira, J.N., Geraldes, C.F., Aime, S., Terreno, E. MRI tracking of macrophages labeled with glucan particles entrapping a
water insoluble paramagnetic Gd-based agent. Mol Imaging Biol. 2013;15:307-15.
Rizzitelli, S., Giustetto, P.,
Cutrin, J.C., Delli Castelli, D., Boffa, C., Ruzza, M., Menchise, V., Molinari,
F., Aime, S., Terreno, E. Sonosensitive theranostic liposomes for preclinical
in vivo MRI-guided visualization of doxorubicin release stimulated by pulsed
low intensity non-focused ultrasound J Control Release 2015 Jan; 202C: 21-30 |
PMID: 25626083.
▼ Imaging Tumor Acidosis |