Regenerating CNS white matter using induced pluripotent stem cells

 描述（由申请人提供）：使用诱导多能干细胞再生CNS白色物质-脑室周围白质软化症（PVL）是早产儿神经系统发病的主要原因，导致脑瘫和认知问题。PVL的主要神经病理标志是局灶性和弥漫性脑室周围白色物质损伤，其特征在于髓鞘形成前少突胶质细胞（OLs）的耗竭和髓鞘形成障碍。目前尚无有效的PVL治疗方法。最近，开发用于新生儿脑损伤的细胞疗法获得了越来越多的支持。我们的实验室已经确定PVL研究为我们研究计划的战略重点领域。我们的长期目标是确定潜在的基于干细胞的PVL治疗策略。累积研究表明，不同的干/祖细胞制剂移植治疗新生儿缺氧缺血性损伤的潜力。高纯度、高均一性的细胞是细胞发育的前提 治疗然而，目前在获得用于移植研究和未来临床使用的同质干/祖细胞方面存在共同的困难。此外，用于移植的最佳细胞类型仍不清楚。在人类组织和PVL动物模型中的研究表明，并不缺乏少突胶质祖细胞（OPC），因为它们的增殖在PVL损伤后增加，但它们的成熟在很大程度上延迟。细胞死亡是 主要见于髓鞘形成前的OLs，但不见于神经元。因此，神经元祖细胞和OPCs可能不是PVL损伤的最佳候选者。基于我们的初步数据，在这里，我们建议开发一种基于星形胶质细胞的细胞治疗新生儿脑损伤。我们最近的工作已经成功地从人胚胎干细胞（hESC）中产生了高同质性和纯度（> 95%）的未成熟星形胶质细胞。我们进一步证明了hESC衍生的星形胶质细胞的移植在体外和体内都表现出强的神经保护作用。星形胶质细胞越来越被认为是发育过程中髓鞘形成和损伤后髓鞘再生过程中的关键参与者。我们一直致力于从成纤维细胞中产生人诱导多能干细胞（hiPSC），并将其分化为用于髓鞘再生和修复的OPC。hiPSC相对于hESC的主要优点是它们是在移植后可能不经受免疫排斥的同基因细胞的无限来源。我们已经将我们的高效星形胶质细胞分化方案应用于hiPSC并产生hiPSC衍生的未成熟星形胶质细胞。我们的初步观察表明，hiPSC衍生的未成熟星形胶质细胞促进OPCs在体外成熟为髓鞘少突胶质细胞。基于这些先前的和初步的结果，我们建议在我们建立的小鼠PVL模型中检查hiPSC衍生的星形胶质细胞的移植是否促进新生儿脑损伤后的髓鞘再生，并且还将探索潜在的机制。这项新的研究可能会导致一种新的hiPSC衍生的基于星形胶质细胞的PVL细胞疗法，也将为OL和星形胶质细胞之间的相互作用提供新的见解，这是一个以前研究不足的研究领域。通过该项目获得的科学知识可能有利于开发基于干细胞的治疗策略，用于治疗人类神经系统疾病，如PVL。

 DESCRIPTION (provided by applicant): Regenerating CNS white matter using induced pluripotent stem cells - Periventricular leukomalacia (PVL) is the leading cause of neurologic morbidity in premature infants leading to cerebral palsy and cognitive problems. The major neuropathologic hallmark of PVL is focal and diffuse periventricular white matter injury, featured by depletion of premyelinating oligodendrocytes (OLs) and myelination disturbances. No effective treatment for PVL is available. Recently, developing cell therapies for neonatal brain injury has gained increasing support. Our lab has identified PVL research as a strategic area of focus for our research program. Our long-term goal is to determine potential stem cell based therapeutic strategies for PVL. Accumulative studies indicate the therapeutic potential for neonatal hypoxic-ischemic injury with transplantation of different stem/progenitor cell preparations. It is prerequisite to derive cells in high purity and homogeneity for developing cell therapies. However, there is currently a common difficulty in obtaining homogenous stem/progenitor cells for transplantation studies and future clinical use. Moreover, the optimal types of cells for transplantation remain unclear. Studies in human tissues and in animal models of PVL showed that there is no lack of oligodendroglia progenitor cells (OPCs), because their proliferation is increased after PVL injury, but their maturation is largely delayed. Cell death is mainly seen in pre- myelinating OLs, but not in neurons. Hence, neuronal progenitors and OPCs may not be the optimal candidates in the PVL injury. Based on our preliminary data, here we propose to develop an astroglia-based cell therapy for neonatal brain injury. Our recent work has led to successful generation of immature astroglia from human embryonic stem cells (hESCs) in high homogeneity and purity (> 95%). We further demonstrated that transplantation of the hESC-derived astrocytes exhibited strong neuroprotective effects both in vitro and in vivo. Astrocytes are increasingly recognized as a crucial player in the myelination process during development and remyelination process after injury. We have been working on generation of human induced pluripotent stem cells (hiPSCs) from fibroblasts and their differentiation into OPCs for myelin regeneration and repair. A main advantage of hiPSCs with respect to hESCs is that they are an unlimited source of isogenic cells that might not be subjected to immune-rejection after transplantation. We have applied our efficient astroglial differentiation protocol o hiPSCs and generated hiPSC-derived immature astroglia. Our preliminary observation indicated that hiPSC-derived immature astrocytes promoted the maturation of OPCs into myelinating oligodendrocytes in vitro. Building upon these previous and preliminary results, we propose to examine whether transplantation of hiPSC-derived astrocytes promotes remyelination after neonatal brain injury in our established mouse PVL model, and the underlying mechanisms will also be explored. This novel study may lead to a new hiPSC-derived astroglia-based cell therapy for PVL, and will also provide new insight into the interaction between OLs and astrocytes, a previously understudied area of investigation. The scientific knowledge to be acquired through this project is of likely benefit to the development of stem cell based therapeutic strategies for treating human neurological disorders such as PVL.