Our previous studies demonstrated that when neural stem cells (NSCs) of the C17.2 clonal line are transplanted into the intact or 6-hydroxydopamine (6-OHDA) lesioned rat striatum, in most, but not all grafts, cells spontaneously express the dopamine (DA) biosynthetic enzymes, tyrosine hydroxylase (TH), and aromatic L-amino acid decarboxylase (Yang, M., Stull, N. D., Snyder. E. Y., Berk, M. A., and Iacovitti, L. (2002). Exp. Neurol.). 2. These results suggested that there were certain conditions which were more conducive to the development of DA traits in NSCs and possibly other neurotransmitter phenotypes. 3. In the present study, we modified a number of variables in vitro (i.e. passage number, confluence) and/or in vivo (degree, type, and site of injury) before assessing the survival, migration. and differentiation of engrafted NSCs. 4. We found that low confluence cultures were comprised exclusively of flattened polygonal cells, which when transplanted, migrated widely in the brain but did not express TH. 5. In contrast, high confluence cultures contained both polygonal cells and an overlying bed of fusiform cells. 6. When these NSCs were maintained for 12-20 passages and then transplanted, virtually all engrafted cells in 65% of the grafts expressed TH but not markers of other neurotransmitter systems. 7. Importantly, all TH+ grafts were accompanied by significant physical damage to the brain while TH- grafts were not, suggesting that local injury-related factors were also important. 8. Of no apparent influence on TH expression, regardless of how cells were grown prior to implantation, was the site of transplantation (cortex or striatum) or the degree of chemical lesion (intact, partial or full). 9. We conclude that transplanted NSCs can express traits specifically associated with DA neurons but only when cells are grown under certain conditions in vitro and then transplanted in proximity to injury-induced factors present in vivo.
摘要
我们之前的研究表明，当将C17.2克隆系的神经干细胞（NSCs）移植到完整或6-羟基多巴胺（6-OHDA）损伤的大鼠纹状体中时，在大多数（但并非所有）移植体中，细胞会自发表达多巴胺（DA）生物合成酶、酪氨酸羟化酶（TH）和芳香族L-氨基酸脱羧酶（Yang, M., Stull, N. D., Snyder. E. Y., Berk, M. A., and Iacovitti, L. (2002). Exp. Neurol.）。2. 这些结果表明，存在某些条件更有利于神经干细胞中DA特性以及可能的其他神经递质表型的发育。3. 在本研究中，我们在评估移植的神经干细胞的存活、迁移和分化之前，在体外（即传代次数、汇合度）和/或体内（损伤程度、类型和部位）改变了一些变量。4. 我们发现，低汇合度培养物仅由扁平多边形细胞组成，这些细胞移植后在脑中广泛迁移，但不表达TH。5. 相比之下，高汇合度培养物包含多边形细胞和上层的梭形细胞层。6. 当这些神经干细胞维持传代12 - 20次然后移植时，65%的移植体中几乎所有移植细胞都表达TH，但不表达其他神经递质系统的标志物。7. 重要的是，所有TH +移植体都伴有对脑的明显物理损伤，而TH -移植体则没有，这表明局部损伤相关因素也很重要。8. 移植部位（皮层或纹状体）或化学损伤程度（完整、部分或完全）对TH表达没有明显影响，无论植入前细胞如何培养。9. 我们得出结论，移植的神经干细胞可以表达与DA神经元特异性相关的特性，但前提是细胞在体外特定条件下培养，然后移植到体内存在的损伤诱导因子附近。
