Cationic Polymers with Cells

This review aims to summarize various biological interactions of cationic polymers in the bloodstream and at a cell level. We attempt to relate the biological aspects of the uptake of these macromolecules to the pharmaceutical facets of polymer design in drug and gene delivery. The present 

G PEL Homopolymer of the amino acid t-lysine Drug delivery 60-62 

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The method by which a DNA vector is trafficked intracellularly may have important implications on the efficiency of gene delivery. If DNA vectors are trafficked to sites far from the nucleus, gene delivery will be hindered by the diffusion-limited cytoplasm. PEI and polylysine are both cationic polymers with the ability to condense DNA however, they have been shown to traffic to different intracellular destinations [198] and result in different transfection efficiencies [199]. In addition, particles of different chemistries were routed differently by the same cell type [200]. Understanding the intracytoplasmic transport of DNA vectors will be critical if higher-efficiency vectors are to be engineered. 

Various biodegradable polycarbonate(s) (PC) polymers have been fabricated via the organocatalytic ring-opening polymerisation of functional cyclic carbonate monomers, which were quarternised to create cationic polymers with various pendent structures such as alkyl, aromatic and imidazolinium (Figure 8.4). These polymers have shown excellent antimicrobial properties and haemolytic characteristics when assayed using rat red blood cells [98]. 

Different biomaterials have been tested in combination with MSCs for developing engineered tissues and delivering cells and/or drugs for in vivo applications. Here we briefly review the main materials used to construct biocompatible scaffolds and their combination with cationic polymers, with particular emphasis on chitosan. 

The plasma membrane presents cationic polymers with a substantial barrier to successfully gaining entry to the cell, as it is a dynamic and a relatively lipophilic structure that restricts the admittance of large, hydrophilic or charged molecules. The contribution of certain pathways in the uptake of cationic polymer-mediated gene delivery is not well understood it is generally believed that the uptake of polyplexes predominantly oecurs through endocytosis, although multiple mechanisms for endocytosis have been described to date and the current question is which pathway of endocytosis is responsible for cationic polymer uptake. 

In summary, various strategies have been introduced to refine non-viral vectors, including the development of composite carrier materials or biodegradable polymers with reduced toxicity, incorporation of cell targeting and additional transport domains for effective and specific delivery, a combination of cationic polymers with lipids to facilitate endocytosis, etc. With respect to the transfection approaches, there is a tendency to mimic the microenvironment of tissues by transferring the conventional 2D substrate... 

Plasmid DNA can be complexed electrostatically with cationic polymers. These complexes can be used for gene transfer [241]. Like the complexes of DNA with cationic lipids these complexes adhere to the cell surface with their cationic surface charges. Thereafter, they are internalized, presumably by adsorptive endocytosis. 

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