Biomedical Engineering Reference
In-Depth Information
Fig. 15.8
Design of 30-helix DNA origami tube and endocytotic pathway.
Left
: three different
types of CpG-H0s with (
I
) unmodified phosphate backbone, (
II
) phosphorothioate (PTO)-modified
backbone, and (
III
) partly PTO-modified backbone.
Middle
: computer model of front (
bottom
)
and side (
top
) view of 30-helix tube.
Blue cylinders
indicate double helices;
black lines
indicate
possible connection sites for CpG sequences.
Right
:(
1
) DNA origami tube internalized by
endocytosis; (
2
) vesicle segregated by the Golgi apparatus containing the transmembrane Toll-like
receptor 9 (TLR9); (
3
) fusion of endosome with DNA origami tube and TLR9 containing vesicle;
(
4
) recognition of CpG sequence by TLR9 and starting signaling cascade; (
5
) expression of surface
molecules and release of cytokines that stimulate the further immune response (Reprinted with
permission from Ref. [
17
]. Copyright 2011 American Chemical Society) (Color figure online)
fluorescein isothiocyanate (FITC) to the DNA origami nanotube. Their results
showed that, just as the DNA tetrahedron structure, the functionalized hollow DNA
origami tube exhibited excellent cell permeating capabilities and is important for
the internalization of the functional CpG; they also demonstrated that once inside
the cells, the DNA nanostructure locates at the endosome of the cell.
The immunostimulatory effects test experiments also showed that much efficient
delivery rates by DNA origami tube structures enabled more CpGs transfected
into cells, correspondently binding and activating Toll-like receptor 9 (TLR9), and
then the downstream pathway produced much high levels of secretion of various
cytokines like interleukin (IL)-6; they also confirmed the results by flow cytometry
measurements of the early activation marker CD69 on the surface of dendritic cells.
Their control experiments also showed that the efficacy of the DNA origami
tubes for delivery of CpG oligonucleotides is superior to the lipid transfection
reagent Lipofectamine, which mediates intracellular delivery of oligonucleotides.
And while Lipofectamine displayed some level of toxicity to the cells, the DNA
origami nanotubes did not affect the growth of the cells.
Their results showed that the hollow DNA origami nanotube structure might be
another candidate for the drug delivery nanocarrier systems, due to its size, structure
compactness, and programmability. However, they did find that no significant
differences in cytokine secretion as well as cell activation for DNA tubes carrying
the CpG-H's on the inner surface or on the outer surface of the DNA nanotubes,
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