Endocytotic uptake of small unilamellar liposomes by human trophoblast cells in culture

Abstract

We evaluated the mechanism of uptake of carboxyfluorescein-containing small unilamellar liposomes of different surface charge by trophoblast cells in culture. Carboxyfluorescein-encapsulated neutral liposomes were prepared by using equimolar concentrations of lecithin and cholesterol. Anionic and cationic liposomes were prepared by adding dicetylphosphate and stearylamine. Trophoblast cells from human term placenta were cultured and incubated on the first day at 37 degrees C with liposome-encapsulated carboxyfluorescein or 500 nM of free carboxyfluorescein. The mechanism of uptake was determined by pre-treating the cells with metabolic inhibitors: 2 mM of sodium azide and 25 mM of deoxyglucose for 30 min. The uptake of liposomes was also evaluated both qualitatively under fluorescent microscope and quantitatively by measuring carboxyfluorescein fluorometrically. The uptake of free carboxyfluorescein and cationic liposomes was comparable. The anionic liposomes were taken up by the trophoblast cells more avidly than the neutral (13.2 +/- 1.6 versus 9.5 +/- 1.4%; P <0.01), cationic (2.9 +/- 0.4%; P <0.001) and the free carboxyfluorescein (2.1 +/- 0.9%; P <0.01). When cells were pre-treated with metabolic inhibitors, the uptake of anionic (5.9 +/- 1.8%; P <0.001) and neutral liposomes (4.0 +/- 0.8%; P <0.01) was significantly reduced, whereas uptake of cationic and free carboxyfluorescein remained unaltered. This study indicates that small unilamellar liposomes are internalized by the trophoblast cells in culture by an energy-dependent pathway; most probably by endocytosis. The neutral and anionic liposomes are internalized more avidly than cationic liposomes.

Glutathione disulfide liposomes – A research tool for the study of glutathione disulfide associated functions and dysfunctions

“…Cationic liposomes have been extensively used in gene delivery due to the electrostatic interaction with the negatively charged DNA [15], [16], [17], [20]. Cationic liposomes help increase the uptake of the entrapped materials through electrostatic interaction between positively charged liposomes and negatively charged cell membrane [15], [16], [17], [21]. In general, the cellular uptake of liposomes occurs through membrane fusion and receptor-mediated endocytosis [15], [16], [17], [22], [23].…”

Therapeutic and Safety Considerations of Nanoparticle-Mediated Drug Delivery in Pregnancy

“…However, published research on the topic of nanoparticle passage across the placenta is relatively sparse, and several recent reviews [34,37] and Government reports [38] have highlighted this as an area in need of more research. We do not yet have a complete understanding of transplacental uptake and transport mechanisms for all nanomaterials [34], although there is evidence that for some nanoparticles it occurs via an energy-dependent process [7]. However, in preliminary studies, we have shown that uptake of positively charged polymeric nanoparticles by trophoblasts takes place via dynamin-mediated (clathrin-caveolin-dependent) endocytosis [39], supporting other studies indicating Arterial fetal blood (delivered via the umbilical cord) perfuses the placenta through villous capillaries, where gas and nutrient exchange occurs.…”

“…Placental uptake and transfer is regulated primarily by maternal blood flow and the properties and characteristics of the syncytiotrophoblast membrane. Part of this diagram was adapted from North Carolina State University, WolfWikis [ that nanoparticles enter the placenta via endocytotic uptake [7,34]. It should be noted here that endocytotic uptake into trophoblasts and transplacental transport to the fetus are two distinct processes.…”

“…testing of new drug delivery modalities in pregnancy that offer the possibility of administering effective maternal, placental and fetal therapeutics with excellent selectivity and safety. Although widely investigated in the context of diseases such as cancer [6], the nanotherapeutic revolution has yet to be embraced by maternal-fetal medicine, despite the fact that it has been around for decades and its potential applications in pregnancy were highlighted last century [7]. Nevertheless, this technology has a number of exciting pharmacological properties and advantages (Box 1), which could be exploited to particular effect in the treatment of maternal, placental and fetal conditions where concerns regarding off-target effects and fetotoxicity are particularly prominent and comprise a barrier to therapeutic drug development and evaluation.…”

Preparation and optimisation of anionic liposomes for delivery of small peptides and cDNA to human corneal epithelial cells

“…Anionic liposomes demonstrate greater stability in solution (Zhigaltsev et al, 2002, Phillips and Heydari, 1996), lead to lower aggregation when compared with neutrally charged liposomes, and have increased endocytosis when compared with cationic (Bajoria et al, 1997) and neutral liposomes. Furthermore, two FDA-approved ophthalmic drugs utilize negatively charged, non-liposomal delivery modalities – Restasis (Allergan, for the treatment of chronic dry eye) and Durezol (Alcon, for ocular inflammation) (Lallemand et al, 2012, de la Fuente et al, 2010).…”