Donaldson Angela E, Cai Jingli, Yang Ming, Iacovitti Lorraine
Department of Neurology, Farber Institute for the Neurosciences, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Stem Cells Dev. 2009 Sep;18(7):1003-12. doi: 10.1089/scd.2008.0300.
Although embryonic stem (ES) cells can generate dopamine (DA) neurons that are potentially useful as a cell replacement therapy in Parkinson's disease (PD), associated ethical and practical concerns remain major stumbling blocks to their eventual use in humans. In this study, we examined human amniotic fluid stem (hAFS) cells derived from routine amniocenteses for their potential to give rise to DA neurons in vitro and following transplantation into the 6-hydroxydopamine-lesioned rat brain. We show that undifferentiated hAFS cells constitutively expressed mRNAs and proteins typical of stem cells but also cell derivatives of all three germ layers, including neural progenitors/neurons (nestin, beta-tubulin III, neurofilament). Additionally, these cells expressed mRNAs of an immature DA phenotype (Lmx1a, Pitx-3, Nurr1, Aldh1a1) but not the corresponding proteins. Importantly, treatment with DA differentiation factors using a variety of protocols did not further promote the development of fully differentiated DA neurons from hAFS cells. Thus, Lmx1a, Aldh1a1, AADC, TH, and DAT proteins were not detected in hAFS cells in culture or after transplantation into the PD rat brain. Moreover, by 3 weeks after implantation, there were no surviving AFS cells in the graft, likely as a result of an acute immunorejection response, as evidenced by the abundant presence of CD11+ macrophage/microglia and reactive GFAP+ astrocytes in the host brain. Taken together, these results suggest that further studies will be needed to improve differentiation procedures in culture and to prolong cell survival in vivo if hAFS cells are to be useful as replacement cells in PD.
尽管胚胎干细胞（ES细胞）能够生成多巴胺（DA）神经元，这在帕金森病（PD）的细胞替代治疗中可能具有潜在用途，但相关的伦理和实际问题仍然是其最终应用于人类的主要障碍。在本研究中，我们检测了从常规羊膜穿刺术中获取的人羊水干细胞（hAFS细胞），观察其在体外以及移植到6-羟基多巴胺损伤的大鼠脑内后生成DA神经元的潜力。我们发现，未分化的hAFS细胞组成性地表达典型干细胞的mRNA和蛋白质，同时也表达所有三个胚层的细胞衍生物，包括神经祖细胞/神经元（巢蛋白、β-微管蛋白III、神经丝）。此外，这些细胞表达未成熟DA表型的mRNA（Lmx1a、Pitx-3、Nurr1、Aldh1a1），但不表达相应的蛋白质。重要的是，使用多种方案用DA分化因子处理并未进一步促进hAFS细胞发育为完全分化的DA神经元。因此，在培养的hAFS细胞中或移植到PD大鼠脑内后，未检测到Lmx1a、Aldh1a1、芳香族氨基酸脱羧酶（AADC）、酪氨酸羟化酶（TH）和多巴胺转运体（DAT）蛋白。此外，植入后3周，移植物中没有存活的AFS细胞，这可能是急性免疫排斥反应的结果，宿主脑中大量存在的CD11+巨噬细胞/小胶质细胞和反应性GFAP+星形胶质细胞证明了这一点。综上所述，如果hAFS细胞要作为PD的替代细胞发挥作用，需要进一步研究以改进培养中的分化程序并延长体内细胞存活时间。
