Development of Herpes Simplex Virus as a Gene Transfer Vector for the Central Nervous System. In: Gage FH, Christen Y, editors. Gene Transfer and Therapy in the Nervous System. Berlin: Springer Berlin Heidelberg; 1992. pp. 133-45. [DOI: 10.1007/978-3-642-84842-1_11]

Gene therapy for brain tumors

Gene therapy has opened new doors for treatment of neoplastic diseases. This new approach seems very attractive, especially for glioblastomas, since treatment of these brain tumors has failed using conventional therapy regimens. Many different modes of gene therapy for brain tumors have been tested in culture and in vivo. Many of these approaches are based on previously established anti-neoplastic principles, like prodrug activating enzymes, inhibition of tumor neovascularization, and enhancement of the normally weak anti-tumor immune response. Delivery of genes to tumor cells has been mediated by a number of viral and synthetic vectors. The most widely used paradigm is based on the activation of ganciclovir to a cytotoxic compound by a viral enzyme, thymidine kinase, which is expressed by tumor cells, after the gene has been introduced by a retroviral vector. This paradigm has proven to be a potent therapy with minimal side effects in several rodent brain tumor models, and has proceeded to phase 1 clinical trials. In this review, current gene therapy strategies and vector systems for treatment of brain tumors will be described and discussed in light of further developments needed to make this new treatment modality clinically efficacious.

Herpesvirus-mediated gene delivery into the rat brain: specificity and efficiency of the neuron-specific enolase promoter

1. Herpesvirus infection with genetically engineered vectors is a way to deliver foreign gene products to various cell populations in culture and in vivo. Selective neuronal gene expression can be achieved using the neuron-specific enolase (NSE) promoter regulating expression of a transgene placed in and delivered by a herpesvirus vector. 2. We sought to determine the anatomical specificity and efficiency of herpesvirus-mediated gene transfer into the rat brain following placement of virus particles carrying a transgene (lacZ) under control of the NSE promoter. The virus utilized was thymidine kinase (TK) deficient and therefore replication deficient in the brain. 3. Infusion of 10(6) plaque-forming units of virus into the striatum caused a limited number of striatal neurons to express the lacZ transgene mRNA and protein product 7 days postinfection. In addition, small numbers of neurons expressing the transgene mRNA and protein were found ipsilateral to the viral injection in the frontal cortex, substantia nigra pars compacta, and thalamus. Neurons at these anatomic loci project directly to the striatal injection site. No other cells within the brains of injected animals expressed the lacZ gene. 4. While this herpesvirus NSE vector was capable of introducing novel functional genetic information into postmitotic neurons within defined neuroanatomic constraints, the numbers of neurons expressing detectable levels of beta-galactosidase was minimal. The calculated efficiency of delivery and transgene expression at 7 days postinfection was 1 transgenic neuron per 10(4) virus particles infused. 5. We conclude that NSE probably is not an optimal promoter for use in gene delivery to CNS neurons in herpesvirus vectors and that the efficacy of gene delivery using other neuron-specific promoters placed at various sites in the herpes viral genome needs to be explored.