Complex Formation with Plasmid DNA Increases the Cytotoxicity of Cationic Liposomes

Abstract

Cationic liposomes (CL) are one of the most widely studied non-viral vectors for gene delivery. It is wellknown that CL induces cytotoxicity following lipofection. However, little is known regarding the mechanism involved in the cytotoxicity. In this study, the in vitro cytotoxicity of CL and its complex with pDNA (lipoplex) was investigated, and a part of the mechanism of induction as well. While free pDNA did not show any cytotoxicity, pDNA increased the cytotoxicity of CL via the formation of lipoplex. In addition, the lipoplex-induced cytotoxicity increased in a lipoplex dose-dependent manner, irrespective of the type of pDNA, cell line and the absence or presence of serum. An assay showed that apoptosis was largely induced by treatment with the lipoplex (lipofection), but not with CL alone, in the tested range of concentration of CL and pDNA. Furthermore, following treatment with lipoplexes, the cells exhibited the morphological features of apoptosis and DNA fragmentation. A cDNA microarray study showed that the lipofection up-regulated 45 genes related to apoptosis, transcription regulation and immune response. These results clearly indicate that pDNA in the lipoplex increases the cytotoxicity of CL as a result of inducing apoptosis. The fundamental principle for gene therapy is to deliver gene-based therapeutics to target cells for specific gene targeting with minimal cytotoxicity. Our results suggest the possibility that cytotoxicity induced by lipofection, accompanied by gene changes, could intrinsically exacerbate, attenuate or even mask the desired effects of gene-based therapy.

γ-Polyglutamic acid-coated vectors for effective and safe gene therapy

“…The strong positive charges of polyplexes and lipoplexes are known to cause severe cytotoxicity by interaction with the negative surface of the cellular membrane [27]. In this experiment, polyplexes and lipoplexes also showed strong cytotoxicity (Fig.…”

Engineering a waste management enzyme to overcome cancer resistance to apoptosis: adding DNase1 to the anti-cancer toolbox

“…Background apoptosis can reflect spontaneous apoptosis that occurs in untreated neoplasms or apoptosis induced by DNA-liposome complexes. 32,33 DNA fragmentation assay for apoptosis assessment. DNA fragmentation was most extensive after treating melanoma cells with the actin-resistant DNase1 gene constructs (C11 and C13), reduced after treatment with either C19 or C07, and minute or absent after treatment with C18, C07 or WT DNase1 (Figure 7).…”

Transfection of myeloid leukaemia cell lines is distinctively regulated by fibronectin substratum

“…The liposome-mediated transfection interferes with the cell viability. The toxicity arisen from the cationic lipid-DNA complex may vary according to chemical composition of the liposome, the amount of DNA, and the type of the host cell (Uchida et al 2002;Pelisek et al 2002;Nguyen et al 2007). Therefore, the efficiency of gene delivery is generally inversely proportional to the cell viability.…”