Vector-mediated drug delivery to the brain

As a consequence of the growing ageing population, many neurodegenerative d iseases, cancer and infections of the brain will become more prevalent. Des pite major advances in neuroscience, many potential therapeutic agents are denied access to the central nervous system (CNS) because of the existence of the blood-brain barrier (BBB). This barrier is formed by the endothelial cells of the brain capillaries and its primary characteristic is the imper meability of the capillary wall due to the presence of complex tight juncti ons and a low endocytic activity. The EBB behaves as a continuous lipid bil ayer and prevents the passage of polar and lipid-insoluble substances. The BBB is, therefore, the major obstacle to drugs that are potentially useful for combating diseases affecting the CNS. Extensive efforts have been made to develop CNS drug delivery strategies in order to enhance delivery of the rapeutic molecules across the BBB. The current challenge is to develop drug -delivery strategies that will allow the passage of therapeutic drugs throu gh the BBB in a safe and effective manner. This review focuses specifically on the strategies developed to enhance drug delivery across the EBB with a n emphasis on the vector-mediated strategy.