Pharmaceutical Manufacturing Handbook: Production and

502 LIPOSOMES AND DRUG DELIVERY
Percent of cells
120
100
80
60
40
20
0
Control ATRA Bare
DOTAP/
cholesterol
liposome
Viable cells
Apoptosis cells
Necrotic cells
ATRA/ H2O2 DOTAR/
cholesterol
liposome
FIGURE 16 Flow cytometric analysis of A549 cells treated with 1.0 μ M ATRA, bare
DOTAP/cholesterol liposomes, or ATRA incorporated in DOTAP/cholesterol liposomes for
48 h in A549 cells. As a control. Cells were incubated with 1% DMSO and 400 μ M H 2 O 2 .
Signifi cant differences: ( * ) P < 0.05 vs. control; (#) P < 0.05 vs. ATRA; ( ‡ ) P < 0.05 vs. DOTAP/
cholesterol liposomes. ( Reprinted from ref. 446 after permission of Elsevier .)
phodiester oligonucleotides (PO - ONs) in the cytoplasm, while the phosphothioate
ONs demonstrate unwanted side effects [447] . In order to design better delivery
systems for PO - ONs, the intracellular fate of the PO - ON and PS - ON lipoplexes
with DOTAP/DOPE was investigated after their application on A549 cells. After
endocytosis, endosomal localization, and endosomal escape of the lipoplexes, the
ONs were localized in the nuclei. However, PO - ONs were degraded in the nucleus
(degradation products diffuse out of the cells after 2 h) whereas PS - ONs were still
intact and remained in the nucleus for 8 h. It is worth mentioning that PS - ONs were
eliminated from the nucleus and were found in cytoplasmic granules, which indicated
that the cell has a mechanism of elimination of intact PS - ONs. Also, it seemed
that the amount of PO - ONs was quite important for the ONs ’ stability as the
degradation was reduced after injecting 22 μ M , in contrast to complete degradation
with injection of 2 μ M . From the study it was concluded that ON degradation
happened after their release from the lipoplexes. Thus, for the successful delivery
of ONs, they have to remain complexed with their carrier. Polyethylenimine (PEI)
was suggested as a possible carrier due to its proton sponge effect, leading to
endosomal rupture without releasing the ONs as well as graft - pDMAEMA – PEG
[poly(2 - dimethylamino)ethyl methacrylate - co - aminoethyl methacrylate – bearing
polyethylene glycol chains]. According to the authors, probably cationic polymers
are more effi cient than cationic lipids, but lots of work still needs to be done on the
matter.
Ovarian Cancer Ovarian cancers start at the ovaries [448] . They can be either
benign, and so never spread from the ovary, or malignant, in which case they can