Biomedical Engineering Reference
In-Depth Information
genes that differentiate NSCs to oligodendrocytes and neurons, respectively, a significant
increase in the expression of markers for oligodendrocytes and neurons was measured [123].
Nanoparticles are also used for controlled delivery of TGF-β pDNA in cartilage regener-
ation. Polysaccharides can be extracted from the body of
Pleurotus eryngii
fruit by sonica-
tion and then cationized by grafting spermine to its backbone [237, 238]. Deng
et al
.
synthesized NPs encapsulating TGF-β DNA by complex coacervation of the cationized
polysaccharide (CPEPS) with TGF-β pDNA, and used the NPs for differentiation of MSCs
to the chondrogenic lineage [238]. The TGF-β pDNA encapsulated CPEPS NPs showed
lower cytotoxicity, higher transfection efficiency, and higher expression of TGF-β mRNA
compared to polyethyleneimine or Lipofectamine transfection, and 92% of the MSCs were
arrested in the G1 phase after transfection with TGF-β pDNA in CPEPS NPs [238].
Nanoparticles have also been used in the delivery of VEGF antisense oligonucleotides
(ODN) to inhibit expression and secretion of VEGF in human retinal pigment epithelial
cells [239]. Aukunuru
et al
. showed that VEGF ODN encapsulated in poly(lactide-co-gly-
colide) NPs inhibited VEGF expression in the epithelial cells but not its free form. However,
the cellular uptake of the ODN-NPs was lower than that of ODN delivered with Lipofectin
[239]. In summary, NPs are very attractive as a gene carrier to reduce cell toxicity, increase
transfection efficiency, localize the gene delivery system to the targeted cells, and to image
and monitor the distribution of transfected cells
in vivo
.
Nanoparticles for Patterning Stem Cells
Nanoscale topography and pattern of growth factors on the substrate regulate differentiation
and lineage commitment of stem cells [240]. In that regard, NPs and micelles have been used
to fabricate nanopatterned surfaces and matrices to regulate stem-cell fate. In one approach,
a monolayer of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) and HAuCl4 micelles
is formed on a substrate by dip-coating [241]. Next, the micellar array is treated with oxygen
plasma to remove the PS-b-P2VP copolymer, leaving the ordered array of gold NPs on
the substrate (Figure 9.5A). The patterned array of gold NPs is moved to a nonadhesive
fluorosiloxane layer by transfer-molding, followed by transfer to a hydrogel substrate
(Figure 9.5B-E). In another variation of the above approach, an array of gold NPs on a
glass substrate is coated with a photoresist layer and micropatterned by photolithography
[242]. After etching the resist layer and the uncovered NPs, the microstructured nanopattern
is transferred to a hydrogel surface by transfer molding. The patterned hydrogel substrates
(B)
(A)
Fluoropolymer
AU NP pattern
Tr ansfer
molding
(C)
Detach
Substrate
Substrate
Fluoropolymer mold
(D)
Tr ansfer
molding
Hydrogel
(E)
Detach
Fluoropolymer mold
Nanopatterned gel
Figure 9.5
Schematic diagram for fabrication of a nanopatterned hydrogel by micelle nanolithography.
