Gene delivery cells affecting

Cell culture substrate can also the influence gene delivery by affecting the occurrence of endocytosis and, thereby, the uptake of DNA-bound NPs by the cells. Hsu et al. [139] observed that the culture of MSCs on chitosan or HA-modified chitosan membranes increased the intracellular uptake of iron oxide NPs ( 5 nm) as well as naked DNA (3.3 kb, 5 mn) by more than fivefold. The increased internalization of NPs was associated with an increase in clathrin-mediated endocytosis on chitosan ( 50%) and in caveolae-mediated endocytosis on chitosan-HA ( 30-40%). In the case of naked DNA, but not iron oxide NPs, macropinocytosis also occurred on both substrates. 

Three families of polymers have been used to study transfection mechanisms polyamines, polyamides, and polyvinyl type polymers. The transfection efficiencies achievable with these systems vary widely, so an in-depth analysis of each polymer family and subsequent comparison of what affects gene delivery will be discussed in this chapter. In addition to high transfection efficiency, it is important for the polymeric systems to be relatively nontoxic to cells in vitro and not to elicit an immune response in vivo. Thus, the effect of transfection parameters on cytotoxicity and immunogenicity will also be examined. 

Godbey, W.T., Wu, K.K. and Mikos, A.G. (2001) Poly(ethylenimine)-mediated gene delivery affects endothelial cell function and viability. Biomaterials, 22, 471 180. 

In in vitro gene delivery, it is very important to fix the location of it, in order to reduce the experimental error of each data. The efficiency of this gene delivery was not affected even in the presence of serum. Moreover, the gene expression was observed even under the condition of US exposure for 1 s. From these results, it was suggested that this system could immediately deliver plasmid DNA into cells. 

The presence of fetal calf serum (FCS) did not affect the transfection efficiency of the chitoplexes, whereas the transfection efficiency of DOTAP-DNA complexes was decreased. Cells remained 100% viable in the presence of chitosan oligomers whereas viability of DOTAP treated cells decreased to 50% in both cell lines. Both DOTAP-DNA lipoplexes and chitoplexes resulted in less transfection efficiency in Caco-2 cell cultures than in COS-1 cells however, quaternized chitosan oligomers proved to be superior to DOTAP. The effects on the viability of Caco-2 cells were similar to the effects observed in COS-1 cells. This report is also in line with the earlier one suggesting that chitosan-DNA complexes present suitable characteristics and less cytotoxic compared to lipid gene carriers and thus has the potential to be used as gene delivery vectors. 

Poly(beta-amino esters) are cationic, hydrolytically degradable polymers that can be produced as polymeric NPs for gene delivery. Green et al. [71] developed small ( 200 nm), positively charged ( 10 mV), polymeric NPs by the self assembly of poly(beta-amino esters) and DNA. These NPs had four times greater gene delivery efficacy than those observed for Lipofectamine 2000 in human embryonic stem (ES) cells. These materials exhibited minimal toxicity and did not adversely affect the colony morphology or cause nonspecific differentiation of the ES cells. 

Factors Affecting Gene Delivery Efficiency of NPs 6.1 Cell Type... 

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