Cytotoxicity issues pertinent to lipoplex-mediated gene therapy in-vivo

Abstract

Cationic liposomes bind with nucleic acids such as plasmids and oligodeoxynucleotides to form complexes known as lipoplexes. Although these lipoplexes have several advantages over other forms of nucleic acid transfer methods in cell culture and in-vivo, toxicity remains a problem, especially in-vivo. Nevertheless, these carriers have been used in clinical trials against cystic brosis and cancer and their usage is attributed mainly to their versatility, especially when it comes to the range of routes available for administration of nucleic-acid-based drugs in-vivo.

Thiolated chitosan nanoparticles as a delivery system for antisense therapy: evaluation against EGFR in T47D breast cancer cells

“…Western blot and immunocytochemical results showed a significant downregulation of this protein in all treated groups except those treated with FBS-free RPMI, NAC-C, NAP-C, and chitosan ( Figure 7A and B). The results show that ASOND-loaded particles ( Figure 7A [5,8,11]) downregulated EGFR expression approximately twice as much as free ASOND ( Figure 7A [2]). DOXloaded nanoparticles ( Figure 7A [6,9,12]) showed a similar result to free DOX ( Figure 7A [3]).…”

“…The control cells and cells treated with empty particles showed expression of EGFR protein in cytoplasmic portion and the membrane of the cells ( Figure 7B [1, 4, 7, 10]). The intensity of the stain decreased through treatment with either free DOX or ASOND ( Figure 7B [2,5]) and the expression was very low when nanoparticles loaded with DOX and ASOND were incorporated ( Figure 7B [3,6,8,9,11]). Normally EGFR protein present on the cell membrane is internalized after activation of this protein which signifies the binding of this receptor to its substrate and activation of EGFR.…”

“…The toxicity of lipoplexes is closely associated with the administered dose and it may in part result from their large size and the high positive surface charge. 8,9 According to these limitations cationic polymers are interesting alternatives to cationic lipids. Furthermore the self-assembly of polymer nanoparticles does not involve interactions of the polycation molecules with each other, resulting in better control of their physical properties compared with lipoplexes.…”

“…It is clear that because of the high level of cytotoxicity observed with this compound and the mechanism of action, DOX is not the preferred drug in EGFR suppression studies causing high levels of cell death. ASOND ( Figure 6 [2]) decreased the expression of EGFR twice as much as control, while thiolated nanoparticles containing ASOND (Figure 6 [5,8,11]) were twice as effective than ASOND or ASOND + LMWC ( Figure 6 [11]) nanoparticles in EGFR knock down. From drug release, cell survival, and gene expression data it could be concluded that thiolated chitosan nanoparticles containing ASOND decreased the cytotoxic effects of this compound probably due to a slower rate of release, resulting in higher levels of EGFR gene suppression.…”

Branched polyethylenimine-grafted-carboxymethyl chitosan copolymer enhances the delivery of pDNA or siRNA in vitro and in vivo

“…6 Although lipoplexes often showed high transgene expression, their limited use resulted from their nonspecific membrane activity. [7][8][9] A number of cationic polymers have been developed because they can interact with the anionic phosphate groups of naked DNA or RNA, generating compact complexes. [7][8][9][10] Among these, polyethyleneimine (PEI) and chitosan have been widely studied, given their attractive properties for drug delivery.…”