Moloney murine leukemia retroviral vectors are more suitable as tools for gene delivery in vivo in comparison to other vectors due to their stable expression and absence of cytotoxicity. However, because of their low titers and poor proliferation rate in the adult nervous system, the application of retroviral vectors to the nervous system has been limited. To overcome this disadvantage, we have attempted to achieve higher viral titers and apply them to the embryonic mouse brain. By utilizing our improved packaging cell line and concentrating the viral supernatant by the low-speed centrifugation method, we have successfully increased the retroviral titer up to 10(12) cfu/ml. This titer is over 10(6)-fold greater than routinely achieved retroviral titers, and is comparable to, or even higher than, those of adenoviral vectors. We investigated the efficacy of gene transfer into the nervous system, which has thus far proven quite recalcitrant to genetic transfer by characteristically low retroviral titers. Using our retroviral preparation, we have demonstrated the highly efficient delivery and long-term expression of a foreign gene into neural cells both in vitro and in vivo. Moreover, we demonstrated that predominant gene delivery into the neurons of one cortical layer can be achieved by choosing an appropriate date of retroviral infection.
Copyright 2003 S. Karger AG, Basel