[17] - In Vitro Studies of Liposome-Mediated Gene Transfection
Introduction
Liposome-mediated gene transfection in the central nervous system (CNS) is a relatively recent addition to the repertoire of DNA transfection methodologies. Carriers currently used to introduce genes into localized regions of the nervous system through stereotaxic injection include retroviral vectors 3., 28., 37., herpes simplex virus vectors 2., 11., 15., 21., adenoviral vectors 19., 10., and grafted cells 6., 17., 30.. Each of these approaches to gene transfection has its advantages. However, each is also compromised by limitations. DNA transfection using lipid vesicles is an attractive method for introducing genetic information into CNS cells because of the simplicity and safety of this approach. Previously, cationic liposomes have been used to deliver various agents, including plasmid DNA 13., 25., 26., 33., 40.. Furthermore, studies report liposome-mediated β-galactosidase (β-gal) gene transfection and expression in adult murine brain (29). The transient expression produced by liposome-mediated gene transfection may limit its application in diseases caused by genetic defects. However, liposomal transfection of trophic proteins may prove useful for treatment of CNS injury by blunting transient pathological processes and/or facilitating recovery. In addition, liposomes are free of the DNA length constraints that are typical of viral-based delivery systems. Furthermore, several studies suggest that the use of liposomes is not associated with autoimmune responses, toxicity, or gonadal localization after systemic delivery 26., 40..
Section snippets
Optimizing of Liposome-Mediated Gene Transfer in Rat Septohippocampal Cell Cultures
As previous studies have suggested (for review, see Ref. 5), two important aspects of liposome-mediated gene transfection must be considered. First, the ratios of DNA to liposomes play an important role in the efficiency of gene transfection. Second, high levels of liposomes can potentially produce cell lysis. Because different cell lines respond differently to liposome-mediated gene transfer (5), investigators must optimize transfection efficiency in each cell line. Importantly, little is
Sustained Expression of Nerve Growth Factor by Liposome-Mediated Gene Transfer
Exogenous supplementation of nerve growth factor (NGF) has been reported to spare neurons from death and degeneration following injury 9., 18., 24., 36. and to increase choline acetyl transferase (ChAT) activity 31., 35.. Furthermore, long-term NGF administration also increases the activity of protective antioxidant enzymes in rat brain (27). The rodent hippocampus is preferentially vulnerable to a variety of central nervous system insults, including traumatic brain injury and ischemia (8).
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