title: Dynamic bio-adhesion of polymer nanoparticles on MDCK epithelial cells and its impact on bio-membranes, endocytosis and paracytosis.
abstract: Nowadays, concern about the use of nanotechnology for biomedical application is unprecedentedly increasing. In fact, nanosystems applied for various potential clinical uses always have to cross the primary biological barrier consisting of epithelial cells. However, little is really known currently in terms of the influence of the dynamic bio-adhesion of nanosystems on bio-membranes as well as on endocytosis and transcytosis. This was investigated here using polymer nanoparticles (PNs) and MDCK epithelial cells as the models. Firstly, the adhesion of PNs on cell membranes was found to be time-dependent with a shift of both location and dispersion pattern, from the lateral adhesion of mainly mono-dispersed PNs initially to the apical coverage of the PN aggregate later. Then, it was interesting to observe in this study that the dynamic bio-adhesion of PNs only affected their endocytosis but not their transcytosis. It was important to find that the endocytosis of PNs was not a constant process. A GM1 dependent CDE (caveolae dependent endocytosis) pathway was dominant in the preliminary stage, followed by the co-existence of a CME (clathrin-mediated endocytosis) pathway for the PN aggregate at a later stage, in accordance with the adhesion features of PNs, suggesting the modification of PN adhesion patterns on the endocytosis pathways. Next, the PN adhesion was noticed to affect the structure of cell junctions, via altering the extra- and intra-cellular calcium levels, leading to the enhanced paracellular transport of small molecules, but not favorably enough for the obviously increased passing of PNs themselves. Finally, FRAP and other techniques all demonstrated the obvious impact of PN adhesion on the membrane confirmation, independent of the adhesion location and time, which might lower the threshold for the internalization of PNs, even their aggregates. Generally, these findings confirm that the transport pathway mechanism of PNs through epithelial cells is rather dynamic, and is remarkably affected by the adhesion patterns of PNs on the cell membrane.
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Peking University, Beijing 100191, China. wgfang@bjmu.edu.cn and Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. zqdodo@bjmu.edu.cn.
authors.forename: Bing
authors.initials: B
authors.lastname: He
authors.affiliation: Medical and Healthy Analytical Center, Peking University, Beijing 100191, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. zqdodo@bjmu.edu.cn.
authors.forename: Wenbing
authors.initials: W
authors.lastname: Dai
authors.affiliation: Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics (Theranostics), School of Pharmacy, Tianjin Medical University, Tianjin 300070, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.affiliation: Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. zqdodo@bjmu.edu.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. zqdodo@bjmu.edu.cn.
authors.forename: Xueqing
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Peking University, Beijing 100191, China. wgfang@bjmu.edu.cn.
authors.forename: Weigang
authors.initials: W
authors.lastname: Fang
authors.affiliation: Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. zqdodo@bjmu.edu.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000378:metabolism; D002966:Clathrin / Q000737:chemistry; D004285:Dogs; D004705:Endocytosis; D004847:Epithelial Cells / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D005677:G(M1) Ganglioside / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D061985:Madin Darby Canine Kidney Cells; D008567:Membranes, Artificial; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002966:Clathrin; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010743:Phospholipids; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D005677:G(M1) Ganglioside; D002118:Calcium