Chitosan–DNA NPs (~20–500 nm) can be readily formed by coacervation
between the positively charged amine groups on the chitosan and negatively
charged phosphate groups on the DNA. The size of the NP and the degree of
DNA condensation depends upon the nitrogen:phosphate (amine group on chitosan:
phosphate groups on DNA) ratio, molecular weight of chitosan and the degree of
deacetylation [75, 76]. Generally a low molecular weight, highly deacetylated
chitosan at high N:P ratio results in small sized NPs with highly condensed DNA.
Chitosan–DNA NPs have been used for gene delivery in a variety of cell types
including human MSCs and were shown to have lower cytotoxicity than lipoplexes
[77, 78]. Unfortunately, results so far have only been modest. Furthermore, gene
delivery efficiency is dependent on cell type [77, 78].
Several researchers have attempted to improve the gene delivery efficiency of
chitosan–DNA NPs by attaching endosome-disrupting molecules or targeting
ligands such as transferrin [78], KNOB (C-terminal globular domain of the fibre
protein) [75], lactose and lactobionic acid [79, 80], galactose and PEG [79, 81], PEI
[82], trimethyl groups [83], deoxycholic acid [84], pH-sensitive polymer poly
(propyl acrylic acid) (PPAA) [76, 85], etc. to the reactive amine groups on chitosan.
These modifications were successful in improving the gene delivery efficiency
and/or cell-type-specific gene delivery. However, improvement in gene delivery
efficiency was only modest and was generally lower than achieved with standard
gene delivery agents such as Lipofectamine.
Hyaluronan
HA has been used to modify the surface charge, dispersing stability and buffering
capacity of polymers such as PEI and chitosan to form NPs for non-viral gene
delivery [86]. NPs made of HA and chitosan showed lower cytotoxicity and
induced a higher rate of gene integration in neural stem cells and spinal cord slice
tissue compare to those obtained with PEI [86]. Similar results were also obtained
with PEI-introduced chitosan NPs for rat MSCs [55].
Gelatin
Gelatin has also been used as a nanocarrier of DNA for transfecting HeLa cells,
chicken cells and chicken embryos. Tseng et al. [87] encapsulated the DNA into
gelatin to produce NPs by a water–ethanol solvent displacement method. The
DNA–gelatin NPs (~300 nm) were nontoxic to cells and effectively induced
transgene expression 24 h after cell transfection. Direct injection of the
DNA–gelatin NPs in the area opaca of the chicken egg resulted in transgenic
embryos without affecting their embryonic development and hatching.
Nanoparticles for Gene Delivery into Stem Cells and Embryos
63
between the positively charged amine groups on the chitosan and negatively
charged phosphate groups on the DNA. The size of the NP and the degree of
DNA condensation depends upon the nitrogen:phosphate (amine group on chitosan:
phosphate groups on DNA) ratio, molecular weight of chitosan and the degree of
deacetylation [75, 76]. Generally a low molecular weight, highly deacetylated
chitosan at high N:P ratio results in small sized NPs with highly condensed DNA.
Chitosan–DNA NPs have been used for gene delivery in a variety of cell types
including human MSCs and were shown to have lower cytotoxicity than lipoplexes
[77, 78]. Unfortunately, results so far have only been modest. Furthermore, gene
delivery efficiency is dependent on cell type [77, 78].
Several researchers have attempted to improve the gene delivery efficiency of
chitosan–DNA NPs by attaching endosome-disrupting molecules or targeting
ligands such as transferrin [78], KNOB (C-terminal globular domain of the fibre
protein) [75], lactose and lactobionic acid [79, 80], galactose and PEG [79, 81], PEI
[82], trimethyl groups [83], deoxycholic acid [84], pH-sensitive polymer poly
(propyl acrylic acid) (PPAA) [76, 85], etc. to the reactive amine groups on chitosan.
These modifications were successful in improving the gene delivery efficiency
and/or cell-type-specific gene delivery. However, improvement in gene delivery
efficiency was only modest and was generally lower than achieved with standard
gene delivery agents such as Lipofectamine.
Hyaluronan
HA has been used to modify the surface charge, dispersing stability and buffering
capacity of polymers such as PEI and chitosan to form NPs for non-viral gene
delivery [86]. NPs made of HA and chitosan showed lower cytotoxicity and
induced a higher rate of gene integration in neural stem cells and spinal cord slice
tissue compare to those obtained with PEI [86]. Similar results were also obtained
with PEI-introduced chitosan NPs for rat MSCs [55].
Gelatin
Gelatin has also been used as a nanocarrier of DNA for transfecting HeLa cells,
chicken cells and chicken embryos. Tseng et al. [87] encapsulated the DNA into
gelatin to produce NPs by a water–ethanol solvent displacement method. The
DNA–gelatin NPs (~300 nm) were nontoxic to cells and effectively induced
transgene expression 24 h after cell transfection. Direct injection of the
DNA–gelatin NPs in the area opaca of the chicken egg resulted in transgenic
embryos without affecting their embryonic development and hatching.
Nanoparticles for Gene Delivery into Stem Cells and Embryos
63