The intracellular fate of an amphipathic pH-responsive polymer: Key characteristics towards drug delivery.
Biopolymers have become important drug delivery systems for therapeutic molecules by enhancing their accessibility and efficacy intracellularly. However, the transport of these drugs across the cell membrane and their release into the cytosol remain a challenge. The trafficking of poly (l-lysine iso-phthalamide) grafted with phenylalanine (PP-50) was investigated using an osteosarcoma cell line (SAOS-2). Colocalisation of this amphipathic biopolymer with endocytosis tracers, such as transferrin and lactosylceramide, suggested that PP-50 is partially internalised by both clathrin and caveolin-mediated endocytosis. Macropinocytosis was also investigated, but a smaller correlation was found between this mechanism and PP-50 transport. A significant decrease in polymer-mediated calcein uptake was found when cells were pre-incubated with endocytosis inhibitors, suggesting also the use of a combination of mechanisms for cell internalisation. In addition, PP-50 colocalisation with endosome and lysosome pathway markers showed that the polymer was able to escape the endolysosomal compartment before maturation. This is a critical characteristic of a biopolymer towards use as drug delivery systems and biomedical applications.
Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
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Mercado
Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
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Orellana-Tavra
Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
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Chen
Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom. Electronic address: nkhs2@cam.ac.uk.
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Slater
D045744:Cell Line, Tumor; D002966:Clathrin / Q000737:chemistry / Q000378:metabolism; D004337:Drug Carriers / Q000737:chemistry*; D004705:Endocytosis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence; D009761:Nystatin / Q000494:pharmacology; D010649:Phenylalanine / Q000737:chemistry; D011107:Polylysine / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
D002966:Clathrin; D004337:Drug Carriers; D011108:Polymers; D009761:Nystatin; D011107:Polylysine; D010649:Phenylalanine
Amphipathic polymer; Caveolin; Clathrin; Endocytosis mechanisms; Macropinocytosis; PP-50