Herpes simplex virus-1 (HSV-1) as a gene delivery vector for neural precursor cells
The thesis work presented evaluated the potential for use of disabled herpes simplex virus-1 (HSV-1) as gene delivery vectors for neural precursor cells and studied the effects of delivered recombinant factors on the de novo development of dopaminergic neurons from neural precursor cells. Highly and less disabled HSV-1 has been studied with respect to gene delivery efficiency and effects on cellular integrity in primary neural progenitor cells, neural stem cells grown as neurospheres, and in endogenous neural stem cell niches in the adult rat. Data from autografts of virally transduced neurospheres into the striatum of rats were also presented. The characteristics of virally transduced neural precursor cells were compared to other viral vector systems reported in literature. With respect to the study of differentiation factors, work has concentrated on fibroblast growth factor 8b (FGF8b). This has demonstrated that FGF8b is a mitogen for neural precursor cells in vitro. The study showed that neural stem cells isolated from different regions of the developing brain can be expanded in FGF8b alone and retain their stem cell characteristics, e.g. the capacity of self-renewal and multipotentiality. Growth curves and dose responses of neural precursor cells expanded in FGF8b further confirmed these findings. The study also showed survival effects of FGF8b on dopaminergic neurons derived from mesencephalic precursor cells. Further the effects of FGF8b on proliferation and differentiation of endogenous stem cells were also investigated. Finally, the thesis work involved the construction and generation of highly and less disabled viruses expressing FGF8b, sonic hedgehog, basic fibroblast growth factor, and the transcription factor nurr1. Expression and bioactivity of the various constructs was confirmed. The effects of these factors on dopamine neuron development were then studied in vitro using neural progenitors and neural precursor cells for which gene delivery had been optimized in the first part of this thesis.