I'm preparing cationic liposomes in order to perform in vitro cell assays, so we need to test cytotoxicity first. But I'm not sure if the problem is stearylamine as itself or a high zeta potential. Do you know if cationic liposomes are always cytotoxic to macrophages? Or it depends on the zeta potential? Thanks a lot.
Dear David,
Please read the following text which was taken from the link depicted at the end of this answer:
Cationic liposomes are associated with efficient cellular delivery of drug cargoes and routinely applied for in vitro gene delivery. Electrostatic interactions between positively charged liposomes and the negatively charged cell membranes and cell surface proteoglycans facilitate cell uptake. Unfortunately, cationic liposomes can cause cytotoxicity limiting their safety for clinical use. In RAW264.7 macrophages cationic liposomes containing stearylamine (SA) have previously been shown to induce apoptosis through mitochondrial pathways generating reactive oxygen species (ROS), releasing cytochrome c, caspase-3 and -8 and more recently activating protein kinase C (PKC) δ possibly by cell surface proteoglycan interaction. Consequently interest for drug delivery has turned to neutral and anionic liposomes.
Zuhorn IS, Engberts JBFN, Hoekstra D. Gene delivery by cationic lipid vectors: overcoming cellular barriers. European Biophysics Journal. 2007;36(4-5):349–362. [PubMed]
Wiethoff CM, Smith JG, Koe GS, Middaugh CR. The potential role of proteoglycans in cationic lipid-mediated gene delivery: studies of the interaction of cationic lipid-DNA complexes with model glycosaminoglycans. The Journal of Biological Chemistry. 2001;276(35):32806–32813. [PubMed]
Lv H, Zhang S, Wang B, Cui S, Yan J. Toxicity of cationic lipids and cationic polymers in gene delivery. Journal of Controlled Release. 2006;114(1):100–109. [PubMed]
Iwaoka S, Nakamura T, Takano S, Tsuchiya S, Aramaki Y. Cationic liposomes induce apoptosis through p38 MAP kinase-caspase-8-Bid pathway in macrophage-like RAW264.7 cells. Journal of Leukocyte Biology. 2006;79(1):184–191. [PubMed]
Aramaki Y, Takano S, Tsuchiya S. Cationic liposomes induce macrophage apoptosis through mitochondrial pathway. Archives of Biochemistry and Biophysics. 2001;392(2):245–250. [PubMed]
Arisaka M, et al. Involvement of protein kinase Cdelta in induction of apoptosis by cationic liposomes in macrophage-like RAW264.7 cells. FEBS Letters. 2010;584(5):1016–1020.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065850/
Hoping this will be helpful,
Rafik
Thanks a lot, I'm aware of the studies by the Arisaka and Aramaki group. They have characterized the cytotoxicity of cationic liposomes (and the ones with stearylamine). It depends on the %mol of SA and the lipid concentration rather than on the zeta potential because they tested another cationic liposome (with a higher zeta potential) but with less cytotoxicity. Thanks a lot. I'm gonna check out the rest of the papers.
Dear Rafik Karaman, i am sorry for interrupting, but is that affect can also happen with other cationic liposome like which has DDAB or DOPA?
They seem to be toxic somehow but the toxicity is related to the molecule itself not at all related to the zeta potential. Other cationic lipids are cytotoxic but stearylmine is the most cytotoxic I've found.
Negatively charged lipids are absolutely vital for multitude of cellular processes from membrane signalling (PIP2, PIP3, PA), to peripheral membrane association to membranes (mostly PS and PIPs) to intracellular vesicle trafficking (mostly PIPs) to mitochondrial oxidative phosphorylation (CL, PG). Negatively and positively charged lipids tend to form strong complexes when in the same membrane. I suspect that cationic lipids will also inactive lysosomal lipid degradation in the endosomal pahtway. I imagine that in sufficient concentrations almost any cationic lipid that the cells are unable to metabolize will be toxic to cells. As far as I know, the only natural cationic lipid in humans is sphingosine.
Dear David E. Bautista-Erazo, is there any published paper has studded that and approve it? moreover is any body tried to solve that compound problem?
I am not sure Asim, but if I read something I will send it to you. For now, cationic liposomes and their toxicity is assesed in gene delivery studies.
Dear Asim,
Sorry for the delay in my answer. Yes, all cationic liposomes are expected to behave similarly via the same mechanism which involves interactions between the positive charge and the negatively charged cell membranes. The cytotoxicity will be largely dependent on the strength of those interactions.
Rafik
But also different cationic lipids have different mechanisms of toxicity.
Hi,
The fact is despite the enormous research and development works on liposomes, only a small number of liposomal products have been approved for human use so far. A major drawback in the clinical utilisation of liposomes is the toxicity associated with some of these lipid vesicles. For instance there are many reports on the toxicity of cationic liposomes (Panzner and Jansons 1979; Chawla et al 1979; Campbell 1983; Filion and Phillips 1997, 1998; Dokka et al 2000; Nagahiro et al 2000) with the exact mechanism of toxicity remaining unclear. One reason for the cationic liposome toxicity is believed to be the interaction of the cationic lipids with cell organelle membranes, specifically the anionic lipids making up these membranes (Xu and Szoka 1996). For example, in mitochondrial membranes, cardiolipin is the major anionic lipid, and interaction of this lipid with cationic species would be detrimental to the basic energy reactions of the cell (for a review see Dass et al 1997).
Another postulated mechanism, for cationic lipid-mediated toxicity in the lung, is the involvement of reactive oxygen intermediates (Dokka et al 2000). On the other hand, volatile organic solvents employed in the manufacture of liposomes, including chloroform and methanol, may remain in the final liposome preparation and contribute to potential toxicity and influence the stability of the vesicles (Vemuri and Rhodes 1995; Cortesi et al 1999). Residual solvents in pharmaceuticals, generally known as organic volatile impurities (OVIs), not only have no therapeutic benefits but may also be hazardous to the environment and human health (Dwivedi 2002).
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ALSO SEE ATTACHED PAPER REGARDING CYTOTOXICTY EVALUATION OF ANIONIC LIPOSOMES.
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