Biomedical Engineering Reference
In-Depth Information
has been enhanced by various molecular targeting, such as IL-13 expres-
sion, transferring receptor and LDL surface receptor pathways. Glioma cells
show an up-regulation of expression of IL-13 receptor a2 on their surface
cells. In a recent study, the improvement of internalization of doxorubicin-
loaded nanoliposomes, targeted with conjugated IL-13, and cytotoxicity in
U251 glioma cells has been shown. In an in vivo animal model the authors
demonstrated the inhibition of the growth of subcutaneously implanted
gliomas [187]. In anticancer gene therapy, the efficiency of liposomes has
been increased through surface ligand targeting, via monoclonal antibodies
to specific receptors up-regulated in glioma cells surface such as transfer-
ring receptors, LDL receptors, IL-13 receptors. A biopolymeric gene deliv-
ery nanoparticle has recently been shown to be effective in vivo in delaying
tumor growth. This polymeric nanoparticle-based non-viral gene delivery
vector is cationic albumin-conjugated pegylated nanoparticle, in which is
incorporated a plasmid encoding proapoptotic Apo2 ligand/tumor necrosis
factor-related apoptosis-inducing ligand (Apo2L/TRAIL). After intrave-
nous injection of plasmid-loaded nanoparticles, and subsequent accumu-
lation in a C6 murine glioma model, incorporation of plasmid DNA into
the host cell genome and inhibition of tumor growth, lead to a prolonged
survival in mice bearing implanted C6 gliomas [188]. An alternative thera-
peutic strategy is the photodynamic therapy (PDT) with targeted delivery
systems. PDT involves the intratumoral release of photosensitizers com-
bined with local excitation by an appropriate wavelength of light, resulting
in the production of oxygen and other reactive oxygen species which initiate
apoptosis and cytotoxicity
and microvascular injury, within treated neoplas-
tic tissues. The recent molecularly-targeting approach leads to the selective
detection of cancer cells, through molecular recognition processes, such as
ligand-receptor or antibody-antigen interaction. PDT is an interesting ap-
proach for the treatment of cerebral gliomas, resulting in a very selective
loco-regional therapeutic approach with an important improvement in lo-
cal control of tumors and a significantly improved survival [44]. A recent
in vitro and in vivo study has shown the efficacy of indomethacin-loaded
nanocapsules in significantly reducing the tumor size of implanted glioma
in rats. Moreover pathological analysis demonstrated the lack of some im-
portant malignant characteristics typical of GBM, such as mitotic index and
microvascular proliferation [189].
Gold nanostructures demonstrate great potential in imaging in diagnos-
tics serving as molecular contrast agents. Because of high extinction coef-
ficient gold nanoparticles can be utilized as contrast agents for dark field,
light scattering, and two-photon luminescence imaging. Moreover, gold
nanomaterials were used for signal amplification in photoacoustic tomogra-
phy (PAT). PAT is an advanced diagnostic hybrid technique based on laser-
induced thermoelastic expansion through biological tissue which allows
combining benefits of optical and ultrasound imaging [190]. PAT allowed
