ABSTRACT
The application of nanotechnology and nanoparticulate systems to gene delivery is predicated on the understanding that delivery of DNA alone is, at best, ineffective and, at worst, cytotoxic, and that therefore complexing nucleic acids with an additional agent is highly desirable. In theory, delivery of genetic material would be the
17.1 Gene-Based Medicine................................................................................... 328 17.1.1 What Constitutes Gene-Based Medicine? ........................................ 328 17.1.2 Ideal Gene Delivery Construct ......................................................... 329
17.2 Gene Delivery Process.................................................................................. 330 17.2.1 Binding and Uptake into the Cell ..................................................... 330
17.2.1.1 Receptor-Mediated Uptake ................................................ 330 17.2.1.2 Nonreceptor-Mediated Uptake .......................................... 332
17.2.2 Intracellular Traf›cking.................................................................... 333 17.2.2.1 Traf›cking of AAVs after Clathrin-Mediated Endocytosis ...333 17.2.2.2 Traf›cking after Nucleolin-Mediated Uptake ................... 334 17.2.2.3 Intracellular Traf›cking of Liposomes .............................. 334
17.2.3 Nuclear Import .................................................................................. 335 17.2.3.1 Nuclear Import of Viruses ................................................. 335 17.2.3.2 Nuclear Import of Nucleolin-Bound NPs .......................... 336 17.2.3.3 Nuclear Import of Lipid-Bound or Naked Plasmid DNA .. 336
17.2.4 Gene Expression ............................................................................... 337 17.2.4.1 Genome Conversion, Virus Uncoating, and Expression .... 337 17.2.4.2 Expression of Nonviral Vectors ......................................... 337
17.3 Successful Ocular Gene Delivery ................................................................. 341 17.3.1 Gene Replacement Therapy .............................................................. 341
17.3.1.1 Gene Replacement Using AAV .......................................... 341 17.3.1.2 Gene Replacement Using CK30PEG NPs ......................... 342
17.4 Concluding Remarks ....................................................................................346 References .............................................................................................................. 347
ideal drug solution; a single dose or treatment leading to persistent, elevated gene expression would cause prolonged exposure of the cell/tissue to the therapeutic agent. This could be a replacement gene to combat a loss-of-function or recessive mutation, a knockdown therapy to target a gain-of-function allele, or a protective gene to retard or prevent degeneration for nonmonogenic disorders. In practice, however, achieving this ideal result has been challenging. In this chapter, we discuss the problems that have plagued attempts to develop therapeutically effective ocular gene delivery, the recent work that has been undertaken to combat those problems, and the application of gene-based medicine to the treatment of ocular diseases.
