Cells of the nervous system

Direct in vivo gene transfer to the central nervous system (CNS) using recombinant lentiviral vectors (rLV) has emerged as a powerful technique to overexpress various genes of interest in different neuronal populations. This interest is exemplified by the increasing number of studies using rLV vectors to evaluate therapeutic proteins to correct disorders of the nervous system (1–3) or to explore a protein’s involvement in normal function or pathological processes (4). Compared to conventional trangenic techniques for overexpression, rLVs have several attractive features. For example, the level of transgene expression in cells transduced with a rLV is typically higher than obtained with knock-in techniques and is present already at 3–4 d after injection in vivo (5). Second, the expression may be directed to specific regions or cell populations depending on the anatomical location of the rLV injections as well as the design of the vector system. This may be advantageous for the study design since it allows unilateral overexpression, thereby creating an internal control in functional and morphological studies. Finally, it is considerably less time consuming than creating transgenic mouse lines.