[In vitro models of intestinal and alveolar epithelium cultures in pharmaceutical research]

The progress of modern bio- and information-technology has made an enormous impact on the development of new drugs: At the one hand, computer-aided drug design and automated high-throughput screening has enormously facilitated the chemical synthesis of new drug candidates. At the other hand, the number of macromolecular biopharmaceuticals, such as peptides, proteins, antisense agents or gene vectors is continuously increasing. Whether or not such new entities can indeed be developed to safe and efficient medicines, is largely determined by the question, if these molecules are able to reach their actual target (receptor) within the patient"s body. Often, biological barriers, such as the mucosal epithelium of the gastrointestinal tract cannot be passed. In vitro test systems based on human epithelial cells may help to determine those candidate drugs which are well absorbed after oral application. Moreover, such cell culture models are helpful tools for the discovery for new delivery routes for those molecules, which cannot be administered by oral application. In this context, there is an increasing interest in the pulmonary delivery of drugs, as well as in the development of cell culture systems to model the blood-air barrier represented by the alveolar epithelium.