Microencapsulation and the grafting of genetically transformed cells as therapeutic strategies to rescue degenerating neurons of the CNS.

Abstract

A number of approaches have been developed to deliver growth factors within the central nervous system of adult mammals. Initially a variety of neurotrophic factors were administered either by single intracerebroventricular or local injections directly into brain tissues or via permanently installed cannulae for chronic administrations. More recently delivery systems including conjugates, biodegradable and non-biodegradable implants and microspheres as well as genetically engineered cells have been introduced in order to provide a prolonged supply of neurotrophic factors and to prevent their enzymatic degradation. In this review we examine a variety of means of delivering neurotrophic factors (mainly nerve growth factor) with the primary focus upon the use of microencapsulated neurotrophins and cells genetically modified to produce them. In addition, this review highlights some difficulties and future trends in the development of novel delivery systems hopefully more suitable for investigations in different areas of neuroscience.