Prospects and implications of using chromatin insulators in gene therapy and transgenesis

Gene therapy has emerged from the idea of inserting a wild‐type copy of a gene in order to restore the proper expression and function of a damaged gene. Initial efforts have focused on finding the proper vector and delivery method to introduce a corrected gene to the affected tissue or cell type. Even though these first attempts are clearly promising, seveal problems remain unsolved. A major problem is the influence of chromatin structure on transgene expression. To overcome chromatin‐dependent repressive transgenic states, researchers have begun to use chromatin regulatory elements to drive transgene expression. Insulators or chromatin boundaries are able to protect a transgene against chromatin position effects at their genomic integration sites, and they are able to maintain transgene expression for long periods of time. Therefore, these elements may be very useful tools in gene therapy applications for ensuring high‐level and stable expression of transgenes. BioEssays 26:796–807, 2004. © 2004 Wiley Periodicals, Inc.