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Abstract: The poor survival of dopamine grafts in Parkinson''s disease is one of the main obstacles to the widespread application of this therapy. One hypothesis is that implanted neurons, once removed from the embryonic environment, lack the differentiation factors needed to develop the dopaminergic phenotype. In an effort to improve the numbers of dopamine neurons surviving in the grafts, we have investigated the potential of adenoviral vectors to deliver the differentiation factor sonic hedgehog or the glial cell line-derived neurotrophic factor GDNF to dopamine-rich grafts in a rat model of Parkinson''s disease. Adenoviral vectors containing sonic hedgehog, GDNF, or the marker gene LacZ were injected into the dopamine depleted striatum of hemiparkinsonian rats. Two weeks later, ventral mesencephalic cell suspensions were prepared from embryos of donor ages E12, E13, E14 or E15 and implanted into the vector-transduced striatum. Pre-treatment with the sonic hedgehog vector produced a three-fold increase in the numbers of tyrosine hydroxylase-positive (presumed dopaminergic) cells in grafts derived from E12 donors, but had no effect on E13–E15 grafts. By contrast, pre-treatment with the GDNF vector increased yields of dopamine cells in grafts derived from E14 and E15 donors but had no effect on grafts from younger donors. The results indicate that provision of both trophic and differentiation factors can enhance the yields of dopamine neurons in ventral mesencephalic grafts, but that the two factors differ in the age and stage of embryonic development at which they have maximal effects. [Copyright &y& Elsevier]

Abstract: We have investigated the in vivo dynamics of an adenovirus-based, LacZ expressing vector, RAd36, at different doses, when injected unilaterally into the corpus striatum of normal rats. We have further investigated the characteristics of this vector in the presence of a 6-OHDA lesion of the nigrostriatal pathway. The dopamine-depleting lesion had an effect on both the number and the distribution of cells transduced by the adenoviral vector. The lesioned side of the brain contained significantly greater numbers of β-galactosidase positive cells than the unlesioned side at 3 days, 1 week and 4 weeks post-injection and the distribution of transduced cells was altered by the presence of a dopamine lesion. We conclude that the increased levels of transgene expression seen in the lesioned hemisphere are due to a change in the diffusion characteristics of the injected vector in the lesioned hemisphere. These results indicate that, when investigating the use of virus-based vectors, ultimately for use in gene therapies in the CNS, the in vivo dynamics of the vector need to be assessed not only in the normal brain, but also in the pathological brain state such as animal models of target diseases. [Copyright &y& Elsevier]