Very interesting method for crossing the BBB:
Global non-viral gene transfer to the primate brain following intravenous administration
Yun Zhanga, Felix Schlachetzkia, , , a, * and William M. Pardridge
a Dept. of Medicine, UCLA School of Medicine, Los Angeles, CA, USA 90024
Received 12 September 2002; accepted 5 November 2002. ; Available online 16 January 2003.
Abstract
Expression plasmids encoding either luciferase or -galactosidase were encapsulated in the interior of an "artificial virus" comprised of an 85 nm pegylated immunoliposome, which was targeted to the rhesus monkey brain in vivo with a monoclonal antibody (MAb) to the human insulin receptor (HIR). The HIRMAb enables the liposome carrying the exogenous gene to undergo transcytosis across the blood-brain barrier and endocytosis across the neuronal plasma membrane following intravenous injection. The level of luciferase gene expression in the brain was 50-fold higher in the rhesus monkey as compared to the rat. Widespread neuronal expression of the -galactosidase gene in primate brain was demonstrated by both histochemistry and confocal microscopy. This approach makes feasible reversible adult transgenics in 24 hours...
Molecular Therapy
Volume 7, Issue 1 , January 2003, Pages 11-18
Copyright © 2003 The American Society of Gene Therapy.
...In summary, these studies show that it is possible to achieve widespread expression of exogenous genes throughout the primate brain following a single intravenous injection of a non-viral formulation of the gene. The PIL gene targeting technology enables adult transgenics of the brain within 24 hours. The only other way to achieve an experimental result such as that shown in Figure 3 is with the engineering and breeding of transgenic primates producing bacterial -galactosidase within the brain. The PIL acts as an artificial virus carrying exogenous genes across the biological barriers in brain ( Figure 1). The component of the PIL that is potentially immunogenic is the targeting antibody. However, the immunogenicity of the antibody can be reduced or eliminated with genetic engineering and the production of "humanized" monoclonal antibodies. The chimeric form of the murine 83-14 HIRMAb has been produced, and has equal affinity for the HIR as the original murine antibody [19]. Therefore, the technology is now available to deliver therapeutic genes to the human brain with an intravenous administration without the use of viral vectors. The plasmid DNA is episomally expressed in cells and must be given on repeat occasions depending on the persistence of the transgene. In rats, the gene expression in brain decreases approximately 50% at 6 days following a single intravenous administration of a PIL encapsulated plasmid expressing either -galactosidase [7] or tyrosine hydroxylase [20]. In mice with intra-cranial experimental brain cancer, therapeutic results were achieved with intravenous administrations of the gene medicine given once per week [10]. In rats with experimental Parkinson's disease, striatal tyrosine hydroxylase is normalized at 3–6 days following the single intravenous injection of the gene, whereas gene expression is minimal at 9 days after administration [20]. Therefore, the persistence of the plasmid expression in vivo in the brain is sufficient to allow for the intended pharmacological response, which is reversible owing to the episomal nature of plasmid gene expression [21]. The persistence of plasmid gene expression is enhanced with the administration of either linearized mini-genes [21] or genomic DNA [22]. Therefore, it is possible to prolong the duration of gene expression derived from non-viral, plasmid-based gene therapy... |
