Intracellular Delivery: A Multifunctional and Modular Approach - Intracellular Delivery: Fundamentals and Applications - page 205

Table 1 (continued)

Particle and CPP used Result References

PEG-PEI conjugates, TATp Increased transfection in mice. Kleemann et al. ( 2005 )

Boron carbide nanoparticles,
TATp

Increased translocation in murine
EL4 lymphoma cells, B16F10
melanoma cells. For boron
neutron capture therapy.

Mortensen et al. ( 2006 )

TATp liposomes DNA
complexes

Increased transfection in vitro and
in vivo.

Gupta et al. ( 2007 )

TATp liposomes DNA
complexes.

Increased transfection in vitro
of the antigen presenting cells.

Pappalardo et al. ( 2009 )

Low cationic liposomes-
plasmid DNA complexes
(lipoplexes) modified
with TATp and/or with
anti-myosin monoclonal
antibody 2G4 (mAb 2G4)
specific toward cardiac
myosin

Increased transfection of hypoxic
cardiomyocytes in vitro by
the mAb 2G4-modified TATp
lipoplexes.

Ko et al. ( 2009 )

Increased accumulation of
mAb 2G4-modified TATp
lipoplexes in the ischemic rat
myocardium and significantly
enhanced transfection of
cardiomyocytes in the
ischemic zone in vivo.

3.1 TATp-Modified Liposomes and Lipid-Core Micelles

for Drug Delivery and Imaging

We have successfully modified liposomes and micelles with TATp using ( p -nitrop-
henyl) carbonyl-PEG-PE (pNP-PEG-PE) (Torchilin et al. 2001a, 2003b ). pNP-
PEG-PE can be readily incorporated into liposomes and micelles via its phospholipid
moiety, and it reacts easily with any amino group-containing substrate compound
via its water-exposed pNP group to form a stable and non-toxic carbamate bond
(Fig. 2 ). The reaction between the pNP group and the amino group of the ligand
proceeds easily and quantitatively at pH 8.0, while excessive wfree pNP groups are
readily eliminated by spontaneous hydrolysis. Some possible ways to attach CPPs
to the micellar and liposomal surface are shown in Fig. 3 .
An early study of liposomal delivery with a TATp showed that modification
with TATp (47-57), enhanced delivery liposomes intracellularly to different cells,
such as murine Lewis lung carcinoma (LLC) cells, human breast tumor (BT20)
cells and rat cardiac myocytes (H9C2) (Torchilin et al. 2001b ). The liposomes
were tagged with TATp via the spacer, pNP-PEG-PE, at a density of a few hun-
dreds of TATp per 200 nm liposome vesicle. These preparations of TATp-
liposomes, which allowed for the direct contact of TATp residues with cells,
displayed an enhanced liposome uptake by the cells. This suggested that the
translocation of TATp-liposomes into cells requires direct, free interaction of
TATp with the cell surface. Further studies on the intracellular trafficking of
rhodamine-labeled TATp-liposomes loaded with FITC-dextran revealed that