ASTROCYTE DELIVERY OF GDNF IN PARKINSONS DISEASE

描述：胶质细胞源性神经营养因子(GDNF)是最近发现的一种在帕金森氏病的啮齿动物和灵长类动物模型中都能产生显著的恢复/保护作用的多肽。虽然治疗效果牵涉到它的临床应用，但由于GDNF不能穿过血脑屏障，体内给药的问题仍然是一个问题。使用体外基因治疗方法，申请人已经证明，用复制缺陷逆转录病毒载体转导的星形胶质细胞在培养和脑内移植后表达重组GDNF。该提案中描述的初步研究表明，在小鼠6-OHDA损伤前几天，当移植到黑质附近时，产生GDNF的星形胶质细胞几乎完全保护黑质多巴胺能周围区及其相关的纹状体纤维。本研究旨在进一步研究移植星形胶质细胞表达重组GDNF的特性，并探讨持续暴露于低剂量GDNF降低成年黑质纹状体神经元对6-OHDA毒性敏感性的可能机制。此外，还建议进行实验，以确定通过转基因星形胶质细胞传递的GDNF是否能恢复先前被6-OHDA损伤的萎缩神经元的功能。利用帕金森病小鼠模型，拟进行的研究旨在探讨下列特定目标：1)鉴定转基因星形胶质细胞脑内移植后GDNF的长期表达；2)研究谷胱甘肽系统和磷脂酰肌醇3激酶(PI3K)调控的信号通路在转基因星形胶质细胞体内介导的神经保护中的潜在作用；3)确定产生GDNF的星形胶质细胞是否能恢复6-OHDA诱导的黑质纹状体受损神经元的多巴胺能功能。这些目标将在帕金森氏病的小鼠6-OHDA模型中使用分子、组织培养、行为和神经化学方法的组合来解决。

DESCRIPTION: (Verbatim from the Applicant's Abstract) Glial cell line derived neurotrophic factor (GDNF) is a recently identified peptide shown to elicit marked restorative/protective effects in both rodent and primate models of Parkinson's disease. Although the therapeutic effects implicate its clinical use, since GDNF does not cross the BBB the problem of in vivo delivery still remains an issue. Using an ex vivo gene therapy approach, the applicant has shown that astrocytes transduced with a replication defective retroviral vector express recombinant GDNF in culture and following intracerebral transplantation. Preliminary studies described in the proposal demonstrate that GDNF producing astrocytes provide nearly complete protection of both nigral dopaminergic perikarya and their associated striatal fibers, when implanted near the substantia nigra several days prior to a 6-OHDA lesion in the mouse. The proposed studies are designed to further characterize the expression of recombinant GDNF by grafted astrocytes and to investigate potential in vivo mechanisms by which continuous exposure to low amounts of GDNF confers decreased susceptibility of adult nigrostriatal neurons to 6-OHDA induced toxicity. In addition, experiments are proposed to determine whether GDNF delivered via transgenic astrocytes restores function to atrophic neurons previously damaged by 6-OHDA. Using a murine model of PD, the proposed studies are designed to address the following Specific aims 1) to characterize the long-term expression of GDNF by transgenic astrocytes following intracerebral transplantation 2) to investigate the potential role of the glutathione system and phosphatidylinositol 3 kinase (PI3K) regulated signaling events in GDNF mediated neuroprotection in vivo using transgenic astrocytes and 3) to determine whether GDNF producing astrocytes restore dopaminergic function to damaged nigrostriatal neurons following the onset of degeneration induced by 6-OHDA. These aims will be addressed using a combination of molecular, tissue culture, behavioral and neurochemical methods, in a mouse 6-OHDA model of Parkinson's disease.