Gene delivery systems microspheres

DNA delivery has been described in situ from polymer coatings, microspheres and synthetic matiices. DNA-material hybrid systems promise to enable forms of gene therapy not possible with other gene delivery systems, e.g., polymeric microspheres facilitate the expression of orally administered genes. 

For targeted and controlled delivery, a number of carrier systems and homing devices are under development glass-like matrices, monoclonal antibodies, resealed erythrocytes, microspheres, and liposomes. There are more sophisticated systems based on molecular mechanisms, nanotechnology, and gene delivery. These will be discussed in the following pages. 

The study of bacterial adhesins and inva-sins for the application in drug delivery strat- es has recently become the focus of much attention. Paul and colleagues used an invasin fiasion protein system for gene delivery strat- es (59) and Easson and coworkers (60,61) j used a similar approach for intestinal delivery P of nanoparticles. The latter group found that latex microspheres up to 1 jam coupled to mal-I tose-binding protein, which was fused with invasin, can be internalized by MECK cell monolayers (60,61). 

DDS systems may be ascribed to more than one type, e.g. nanoparticles or microspheres coated with multilayer films. Cationic polymers are extensively used in nucleic acid delivety and the respective delivery systems may also be considered as DDSs. However, since non-viral nucleic acid delivery with a great potential in gene therapy has become such an intensively studied area, it is out of the scope of the present chapter. 

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