Using Stem Cells in Animal Models of Parkinson's Disease

帕金森病（PD）的一种有前途的新疗法是用移植的胎儿中脑组织替代变性的黑质纹状体神经元。虽然这种方法通常在大鼠和猴子中产生显著的功能恢复，但在PD患者的临床试验中的结果不太一致。 争论的焦点是，相对无法标准化人类胎儿移植中的一些关键因素，包括移植细胞的年龄、类型、数量和完整性。 因此，寻找更可靠的多巴胺能（DA）组织来源用于移植变得越来越重要。 一个方向是寻找一系列容易获得的、特征良好的持续自我更新的干细胞或前体细胞，这些干细胞或前体细胞具有分化的能力，理想情况下是自发地并且几乎不需要操作，从而提供了一种取之不尽、用之不竭的统一的替代组织来源。 为此，我们的初步研究结果表明，移植的胚胎小鼠神经干细胞（NSC）的C17.2细胞可以专门分化成神经元，在大多数情况下，可以表达DA性状时，细胞移植到大脑中的帕金森病大鼠。 此外，在使用来自成年人骨髓（MSC）的干细胞的初步研究中，我们已经发现，在与特异性分化因子孵育仅1-2小时后，近100%的MSC将转化为具有突起的β-微管蛋白III+神经元样细胞。 如果这些细胞也表现出与神经干细胞相同的能力，以响应适当的DA分化线索在体内，患者可以提供自己的干细胞来源的自体移植在PD。使用NSC和MSC干细胞模型和多学科方法，我们的具体目标有三个方面：1）确定促进培养中生长的干细胞中有丝分裂后分化的DA表型稳定出现的条件; 2）鉴定促进移植干细胞中DA表型分化的那些因子，和确定移植干细胞中的DA表型是否稳定和持久，以及是否可以在PD大鼠模型中产生运动缺陷的功能恢复。 该研究计划的最终目标是更全面地了解调节干细胞中DA性状分化的细胞和分子过程，并将这些知识应用于治疗帕金森病的移植策略。

One promising new therapy for Parkinson's Disease (PD) involves the replacement of degenerated nigrostriatal neurons with those derived from transplanted fetal mesencephalic tissue. Although this approach has often yielded remarkable recovery of function in rats and monkeys, results in clinical trials with PD patients have been less consistent. At issue, is the relative inability to standardize a number of critical factors in human fetal transplants, including the age, type, number and integrity of cells being grafted. Consequently, finding more reliable sources of dopaminergic (DA) tissue for transplantation has become increasingly important. One direction has been to search for a line of readily available, well-characterized continually self-renewing stem or precursor cells that possess the capacity to differentiate, ideally spontaneously and with the need for little manipulation, into DA neurons, thus providing an inexhaustible and uniform source of replacement tissue. Towards this end, our preliminary findings demonstrate that grafts of embryonic mouse neural stem cells (NSCs) of the C17.2 cell can differentiate exclusively into neurons, which in a majority of cases, can express DA traits when cells are transplanted into the brain of a Parkinsonian rat. In addition, in preliminary studies using stem cells from adult human bone marrow (MSCs), we have found that nearly 100 percent of MSCs will convert into process- bearing, beta-tubulin III+ neuronal-like cells after only 1-2 hours of incubation with specific differentiation factors. If these cells also exhibit the same capacity as NSCs to respond to appropriate DA differentiation cues in vivo, patients could provide their own source of stem cells for autologous grafts in PD. Using NSC and MSC stem cell models and a multidisciplinary approach, our specific goals for this proposal are threefold: 1) Identify the conditions that promote the stable appearance of a postmitotic differentiated DA phenotype in stem cells grown in culture; 2) Identify those factors which promote the differentiation of a DA phenotype in transplanted stem cells and 3) Determine whether the DA phenotype in transplanted stem cells is stable and long lasting, and whether, it can produce functional recovery of motor deficits in a rat model of PD. The ultimate goal of this research program is a fuller understanding of the cellular and molecular processes regulating the differentiation of DA traits in stem cells and apply that knowledge to transplantation strategies for the treatment of Parkinson's Disease.