4.2 NP-Based Gene Delivery for Inducing Differentiation
of Stem Cells
Prior to their transplantation into patients, stem cells need to be differentiated into
the desired cell type (e.g. cardiomyocyte). Targeted differentiation of stem cells can
be achieved by culturing them in the presence of specific growth factors, providing
specific cell culture substrate, modifying cell surface properties and through up- or
downregulation of specific genes. In recent years, genetic engineering has become
an important strategy for the induction and regulation of the targeted differentiation
of stem cells into a specific cell type. At least two strategies (described below) have
been applied to use NPs in inducing and controlling the differentiation of stem cells.
4.2.1 Delivery of DNA- or siRNA-Loaded NPs
Introduction of genes and/or introduction of siRNA to up- and downregulate
specific genes involved in signalling pathways controlling the cell phenotype can
induce specific differentiation of stem cells into specific cell types. For example,
Kim et al. [72] showed that PLGA NPs loaded with SOX9 genes induced
chondrogenesis in human MSCs both in vitro and in vivo. Park et al. [56] further
showed that introduction of the SOX trio (SOX5, SOX6, and SOX9) complexed
with PEI-modified PLGA NPs led to a dramatic increase in the chondrogenesis of
human MSCs in in vitro culture systems. NPs containing siRNAs for silencing
Bcl2l2 and Trib2 were shown to enhance osteogenic and adipogenic differentiation,
respectively, of MSCs [120]. Use of NPs also allows simultaneous introduction of
DNA vector and siRNA and, thereby, enhanced and efficient differentiation [54].
4.2.2 Incorporation of Oligonucleotide- or DNA-Loaded NPs
and Differentiating Agent into Scaffolds
DNA- or siRNA-loaded NPs can be combined with 3D tissue-engineered scaffold
impregnated with or without bioactive molecules. Such systems can provide a
combination of differentiation-inducing gene delivery (by NPs), physical support
and surface properties (by scaffold) and differentiation stimulants (by bioactive
molecules) and, hence, might be a better alternative for target differentiation of
stem cells into a specific cell types and production of specific tissue constructs
for tissue engineering. Cao et al. [121] developed a 3D NP gene delivery system
(3D-NGDS) based on collagen/chitosan scaffolds, in which pTGFb1/calcium phosphate NPs mixed with fibronectin were used to transfect MSCs. They observed that
3D-NGDS could successfully transfect the MSCs and induce chondrogenic differentiation in vitro without dexamethasone. The transfection efficiency was higher
than obtained with the Lipofectamine 2000 method.
Nanoparticles for Gene Delivery into Stem Cells and Embryos
67
of Stem Cells
Prior to their transplantation into patients, stem cells need to be differentiated into
the desired cell type (e.g. cardiomyocyte). Targeted differentiation of stem cells can
be achieved by culturing them in the presence of specific growth factors, providing
specific cell culture substrate, modifying cell surface properties and through up- or
downregulation of specific genes. In recent years, genetic engineering has become
an important strategy for the induction and regulation of the targeted differentiation
of stem cells into a specific cell type. At least two strategies (described below) have
been applied to use NPs in inducing and controlling the differentiation of stem cells.
4.2.1 Delivery of DNA- or siRNA-Loaded NPs
Introduction of genes and/or introduction of siRNA to up- and downregulate
specific genes involved in signalling pathways controlling the cell phenotype can
induce specific differentiation of stem cells into specific cell types. For example,
Kim et al. [72] showed that PLGA NPs loaded with SOX9 genes induced
chondrogenesis in human MSCs both in vitro and in vivo. Park et al. [56] further
showed that introduction of the SOX trio (SOX5, SOX6, and SOX9) complexed
with PEI-modified PLGA NPs led to a dramatic increase in the chondrogenesis of
human MSCs in in vitro culture systems. NPs containing siRNAs for silencing
Bcl2l2 and Trib2 were shown to enhance osteogenic and adipogenic differentiation,
respectively, of MSCs [120]. Use of NPs also allows simultaneous introduction of
DNA vector and siRNA and, thereby, enhanced and efficient differentiation [54].
4.2.2 Incorporation of Oligonucleotide- or DNA-Loaded NPs
and Differentiating Agent into Scaffolds
DNA- or siRNA-loaded NPs can be combined with 3D tissue-engineered scaffold
impregnated with or without bioactive molecules. Such systems can provide a
combination of differentiation-inducing gene delivery (by NPs), physical support
and surface properties (by scaffold) and differentiation stimulants (by bioactive
molecules) and, hence, might be a better alternative for target differentiation of
stem cells into a specific cell types and production of specific tissue constructs
for tissue engineering. Cao et al. [121] developed a 3D NP gene delivery system
(3D-NGDS) based on collagen/chitosan scaffolds, in which pTGFb1/calcium phosphate NPs mixed with fibronectin were used to transfect MSCs. They observed that
3D-NGDS could successfully transfect the MSCs and induce chondrogenic differentiation in vitro without dexamethasone. The transfection efficiency was higher
than obtained with the Lipofectamine 2000 method.
Nanoparticles for Gene Delivery into Stem Cells and Embryos
67