Transplantation site influences the phenotypic differentiation of dopamine neurons in ventral mesencephalic grafts in Parkinsonian rats.
Transplantation site influences the phenotypic differentiation of dopamine neurons in ventral mesencephalic grafts in Parkinsonian rats.
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DOI：
10.1016/j.expneurol.2017.01.010
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发表时间：
2017-05
影响因子：
5.3
通讯作者：
Dunnett SB
中科院分区：
文献类型：
--
作者：
Fjodorova M;Torres EM;Dunnett SB
胎儿中脑祖细胞已被证明能够存活，产生不同种类的多巴胺神经元，并整合到宿主脑中，从而在移植到患者和帕金森病动物模型中后缓解帕金森病症状。中脑中的多巴胺神经元亚群，即A9和A10，可以基于细胞形态和上行轴突投射在解剖学上鉴定。G蛋白门控内向整流钾通道Girk 2和钙结合蛋白钙结合蛋白是目前用于标记（有一些重叠）A9和A10样多巴胺神经元亚型的两种最好的组织化学标记物，分别在中脑和移植物中表达酪氨酸羟化酶的神经元中。这两类多巴胺神经元存活在纹状体的移植物中，并根据表型将轴突投射延伸到其正常的背侧和腹侧纹状体靶。然而，移植到背侧纹状体（A9输入核）的移植物富含表达Girk 2的多巴胺神经元。不同的移植部位是否有利于移植物内一致的多巴胺神经元亚型的差异存活和/或发育仍有待阐明。在这里，我们使用了处于两个发育阶段的大鼠胚胎中脑祖细胞，对应于A9或A10神经发生的峰值，并通过将细胞移植到含有黑质A9多巴胺神经支配靶点的不同前脑区域来检查它们对各自多巴胺能表型的承诺（背侧纹状体），腹侧被盖区A10多巴胺神经支配（脑桥核和前额叶皮质），或只有稀疏的多巴胺但丰富的去甲肾上腺素神经支配（海马）。我们证明，年轻（胚胎日，E12），但不是老年人（E14），中脑组织和移植环境的影响生存和功能整合的特定亚型的多巴胺神经元到宿主大脑。我们还表明，无论供体年龄A9样，Girk 2表达神经元在移植后分化过程中采用多巴胺能表型对环境线索更敏感。这些新的发现表明，多巴胺祖细胞在移植部位使用A9/A10神经支配的靶点来完成成熟，并且通过在比当前实践更早的发育阶段获得中脑组织，可以改善患者中胎儿细胞替代疗法的疗效。年轻的VM供体移植物更大，并且具有增强的A9样多巴胺神经元产量。A9：VM移植物中A10样多巴胺神经元的比例在移植部位之间不同。背侧纹状体促进VM移植物中A9样多巴胺神经元的分化。中脑背侧核略微富集具有A10样多巴胺神经元的移植物。移植部位影响A9和A10样神经元在移植物中的分布。
Foetal midbrain progenitors have been shown to survive, give rise to different classes of dopamine neurons and integrate into the host brain alleviating Parkinsonian symptoms following transplantation in patients and animal models of the disease. Dopamine neuron subpopulations in the midbrain, namely A9 and A10, can be identified anatomically based on cell morphology and ascending axonal projections. G protein-gated inwardly rectifying potassium channel Girk2 and the calcium binding protein Calbindin are the two best available histochemical markers currently used to label (with some overlap) A9- and A10-like dopamine neuron subtypes, respectively, in tyrosine hydroxylase expressing neurons both in the midbrain and grafts. Both classes of dopamine neurons survive in grafts in the striatum and extend axonal projections to their normal dorsal and ventral striatal targets depending on phenotype. Nevertheless, grafts transplanted into the dorsal striatum, which is an A9 input nucleus, are enriched for dopamine neurons that express Girk2. It remains to be elucidated whether different transplantation sites favour the differential survival and/or development of concordant dopamine neuron subtypes within the grafts. Here we used rat foetal midbrain progenitors at two developmental stages corresponding to a peak in either A9 or A10 neurogenesis and examined their commitment to respective dopaminergic phenotypes by grafting cells into different forebrain regions that contain targets of either nigral A9 dopamine innervation (dorsal striatum), ventral tegmental area A10 dopamine innervation (nucleus accumbens and prefrontal cortex), or only sparse dopamine but rich noradrenaline innervation (hippocampus). We demonstrate that young (embryonic day, E12), but not older (E14), mesencephalic tissue and the transplant environment influence survival and functional integration of specific subtypes of dopamine neurons into the host brain. We also show that irrespective of donor age A9-like, Girk2-expressing neurons are more responsive to environmental cues in adopting a dopaminergic phenotype during differentiation post-grafting. These novel findings suggest that dopamine progenitors use targets of A9/A10 innervation in the transplantation site to complete maturation and the efficacy of foetal cell replacement therapy in patients may be improved by deriving midbrain tissue at earlier developmental stages than in current practice. Younger VM donor grafts are bigger and with enhanced A9-like dopamine neuron yield. A9:A10-like dopamine neuron ratios in VM grafts vary between transplantation sites. Dorsal striatum promotes A9-like dopamine neuron differentiation in VM grafts. Nucleus accumbens slightly enriches grafts with A10-like dopamine neurons. Transplantation site influences distribution of A9- and A10-like neurons in grafts.