Enhancing microparticle internalization by nonphagocytic cells through the use of noncovalently conjugated polyethyleneimine

Abstract

Development of micro-and nanotechnology for the study of living cells, especially in the field of drug delivery, has gained interest in recent years. Although several studies have reported successful results in the internalization of micro-and nanoparticles in phagocytic cells, when nonphagocytic cells are used, the low internalization efficiency represents a limitation that needs to be overcome. It has been reported that covalent surface modification of micro-and nanoparticles increases their internalization rate. However, this surface modification represents an obstacle for their use as drug-delivery carriers. For this reason, the aim of the present study was to increase the capability for microparticle internalization of HeLa cells through the use of noncovalently bound transfection reagents: polyethyleneimine (PEI) Lipofectamine™ 2000 and FuGENE 6 ® . Both confocal microscopy and flow cytometry techniques allowed us to precisely quantify the efficiency of microparticle internalization by HeLa cells, yielding similar results. In addition, intracellular location of microparticles was analyzed through transmission electron microscopy and confocal microscopy procedures. Our results showed that free PEI at a concentration of 0.05 mM significantly increased microparticle uptake by cells, with a low cytotoxic effect. As determined by transmission electron and confocal microscopy analyses, microparticles were engulfed by plasma-membrane projections during internalization, and 24 hours later they were trapped in a lysosomal compartment. These results show the potential use of noncovalently conjugated PEI in microparticle internalization assays.

Lasing in Live Mitotic and Non-Phagocytic Cells by Efficient Delivery of Microresonators

“…The experiments described here demonstrate the practical feasability of WGM microlaser-based cell tracking by revealing broad compatibility with cells of different type and origin. For Hela and astrocytes, uptake of small microspheres with sizes ranging from 1 to 3 μm was reported previously21233233. However, here we have shown that with proper surface functionalization these cells can readily internalize WGM resonators with volumes 300-fold larger than this, thus revealing a surprising ability of cells to internalize large polymer spheres.…”

“…In the literature, different liposome coatings have been reported to assist with the uptake of much smaller polymer microspheres (about 2 μm in size) by non-phagocytic cells212324. Liposomes consist of a formulation of neutral and positively charged lipid molecules that can facilitate contact and fusion with negatively charged cell membranes.…”

Hepatocyte-targeting gene transfer mediated by galactosylated poly(ethylene glycol)- graft-polyethylenimine derivative

“…In addition, gene carriers with diameters larger than 200 nm are readily scavenged nonspecifically by monocytes and the reticuloendothelial system 36. A positive surface charge of GPE, which comes from the protonated amino groups on PEI, may be an advantage for cellular uptake, due to the electrostatic interaction between the negatively charged cellular membrane and the positively charged complexes 37,38. As shown in Figure 4, at a w/w ratio of 1, the particle size of GPE/pDNA complexes was 108 nm and the zeta potential was −8.9 mV, indicating that the complexation between GPE and pDNA was incomplete.…”

Surface modification of microparticles causes differential uptake responses in normal and tumoral human breast epithelial cells

“…Thus, with the aim to obtain cationic particles, several approaches have been performed, including their coating with cationic lipids or polymers. Specifically, particle coating with Polyethyleneimine (PEI) has been of particular relevance212223 due to the widely known protonsponge effect, which involves the protonation of PEI amine groups that leads to endo/lysosomal pH buffering, membrane disruption, and ultimate liberation of the content to the cytosol24. Moreover, the proton sponge effect has been shown to be more efficiently achieved when a high molecular weight of PEI is used25.…”