Parkinson’s disease (PD) is a neurodegenerative condition characterized by the progressive and selective loss of dopaminergic (DAergic) neurons in the midbrain. The replacement of neuromelanin (NM)–containing DAergic neurons in the substantia nigra and the enhancement of NM concentration could offer a promising and safe approach to treating PD symptoms. The objective of this study was to investigate and compare the potential of human periapical-cysts mesenchymal stem cells (hPCy-MSCs) and dental pulp stem cells (DPSCs) to differentiate into DAergic NM-producing neurons and to generate functional 3-dimensional (3D) midbrain-like organoids in vitro. We assessed the changes in morphology and behavior of neuron-like cells (NLCs) as well as the expression of molecular markers characterizing the DAergic neurons. Furthermore, we observed electrically active and functionally mature DAergic neurons by means of electrophysiological assays, NM dosage assays, and the quantification of dopamine release by high-performance liquid chromatography. Our results demonstrate for the first time that both hPCy-MSCs and DPSCs are capable of differentiating into NLCs, further confirmed by the increase in lactate levels in the medium of cells exposed to neurogenic conditions. Importantly, we have induced such NLCs to further differentiate into functional DAergic NM-producing neurons. Finally, 3D midbrain-like organoids have been produced from oral stem cells: they appear as neurosphere-like structures diffusely expressing the neural marker β-III tubulin and containing NM-like granules. Our findings open up a novel and fascinating opportunity to rethink oral stem cells, and the derived 3D disease models, as a strategic and reliable tool for unveiling the neurodegenerative alterations.

中文翻译：

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通过口腔干细胞揭示神经退行性改变


帕金森病 （PD） 是一种神经退行性疾病，其特征是中脑中多巴胺能 （DAergic） 神经元进行性和选择性丢失。在黑质中替换含有神经黑色素 （NM） 的 DAergic 神经元并增强 NM 浓度可能为治疗 PD 症状提供一种有前途且安全的方法。本研究的目的是调查和比较人根尖周围囊肿间充质干细胞 （hPCy-MSCs） 和牙髓干细胞 （DPSC） 分化为产生 DA能 NM 的神经元并在体外产生功能性 3 维 （3D） 中脑样类器官的潜力。我们评估了神经元样细胞 （NLC） 形态和行为的变化以及表征 DAergic 神经元的分子标志物的表达。此外，我们通过电生理测定、NM 剂量测定和高效液相色谱法对多巴胺释放的定量观察了电活性和功能成熟的 DAergic 神经元。我们的结果首次证明 hPCy-MSCs 和 DPSCs 都能够分化为 NLC，暴露于神经源性条件的细胞培养基中乳酸水平的增加进一步证实了这一点。重要的是，我们已经诱导此类 NLC 进一步分化为功能性 DAergic NM 产生神经元。最后，口腔干细胞产生了 3D 中脑样类器官：它们表现为神经球样结构，弥漫性表达神经标志物 β-III 微管蛋白并含有 NM 样颗粒。我们的发现为重新思考口腔干细胞和衍生的 3D 疾病模型开辟了一个新颖而迷人的机会，作为揭示神经退行性改变的战略性和可靠工具。