Lipid-Based Pharmaceutical Nanocarriers for Imaging Applications - Nanotechnology for Biomedical Imaging and Diagnostics - page 65

significant images. Therefore, immunoliposomes were used for targeted delivery of
drugs and imaging agents [123].
The first visualization of experimental myocardial infarction with nanocarriers
was achieved in dogs using 111 inCl 3 -loaded immunoliposomes modified with infarct-
specific, antimyosin antibody [124]. The further attempts to use nanocarriers as
imaging agents for myocardial infarction involved long-circulating immunolipo-
somes (including those modified with antimyosin antibody). 111 in-labeled pEg-
modified antimyosin nanocarriers have been shown to accumulate successfully in the
areas of experimental myocardial infarction in rabbits and dogs (via both specific and
nonspecific mechanisms) and provide good gamma-immunoscintigraphic images of
the infarct within several hours upon iV administration [125].
myocardial infarct was also visualized by sonography, when gas-filled nanocarri-
ers were used for infarct imaging in rabbits [126]. still, infarct imaging with nanocar-
riers remains at the level of animal experimentation.
gd-containing phosphatidylserine (ps) liposomes have been used for molecular
imaging of atherosclerosis, since ps residues trigger rapid phagocytosis by macro-
phages know to be present in atherosclerotic lesions [127].
four-dimensional mr microscopy of the mouse heart using gd-liposomes was
used for spatial and temporal resolution as well as for high-resolution fast isotropic
imaging [128].
Liposomes loaded with pET/mr contrast agents were used to follow the ther-
apeutic action of anti-inflammation drugs in atherosclerosis model in rabbits [129].

3.4.4 other organ and tissue imaging with contrast-Loaded Liposomes

The use of microparticulate imaging agents for the visualization of infection and
inflammation sites is based on the ability of microparticulates to extravasate from
the circulation and accumulate in those sites similar to what we already described
for tumors and infarcted tissues. 99m Tc nanocarriers were shown to accumulate
within 30 min in experimental staphylococcal abscess in rats [29]. The same approach
was successfully used in preliminary clinical studies, where deep-seated infections
were visualized with labeled nanocarriers in several patients [130]. Later on, more
advanced 99m Tc nanocarriers labeled using lipophilic chelator and reduced gsH were
shown to accumulate in rats in sites injected with Staphylococcus aureus [131].
Abscesses were visualized within 2 h after the injection of 99m Tc nanocarriers.
despite the fact that tumors also accumulate nanocarriers via the impaired filtra-
tion mechanism, there exists a possibility to discriminate between infection and
tumor using positively charged 67 ga nanocarriers, which do accumulate in tumors
and do not accumulate in infection sites [104].
inflammation sites have also been shown to accumulate contrast-loaded lipid nano-
carrier. Thus, gamma-imaging demonstrated specific accumulation of 99m Tc-loaded
negatively charged liposomes in the inflamed paws of rats with adjuvant-induced
arthritis [132]. Liposomes labeled with 67 ga well enough detected experimentally
induced inflammations in rat, the inflammation-to-muscle accumulation ratio reaching
maximum (32:1) in the case of neutral nanocarriers [104].