Patterned Synthetic Spinal Cords from Human Pluripotent Stem Cells

在神经系统的发育过程中，大量的神经元将在离散的位置发育，获得不同的形状，并与特定的靶细胞群建立联系。神经细胞命运和分化的这种空间组织被普遍认为是由可溶的化学信号指导的，称为形态原。然而，胚胎细胞如何在神经系统发育过程中将形态信息转化为神经细胞分化的空间模式仍然是一个重要的生物学问题。这个项目的目标是通过利用研究人员实验室中建立的基于干细胞的开发模型来具体解决这一重大的知识差距。这一人工合成的人类发育模型将被用作一个可控的实验系统，以确定不同的形态信号如何控制关键信号通路的细胞内活动，从而调节神经细胞的命运。该项目如果成功，将在促进对神经系统发育的基本了解方面取得重大进展，这对诊断、预防和治疗神经系统发育受损所致的神经系统疾病非常重要。在该项目下开发的技术将用于加强K-12外联活动，优先考虑女性和少数族裔学生，并为本科生和研究生提供教育机会。为Ann Arbor和Ypsilanti学区的学生计划的外展活动包括为高中生制定暑期实习生计划，以及为K-12学生的NanoCamps和科技日活动开发教育模块。密歇根大学现有的本科生研究计划将被用来招收本科生参与实验室的研究，并将开发一门新的课程，名为“干细胞生物工程和生物技术”，为研究生为再生医学和疾病建模等新兴领域做准备。胚胎细胞如何以可靠而稳健的方式将发育信号的动态变化转化为基因表达和细胞分化的空间模式仍然是一个谜。因此，该项目的一个基本目标是利用基于人类干细胞的发育模型的最新进展来研究形态原梯度介导的胚胎模式。具体地说，由人类多能干细胞开发的合成微流控图案人类脊髓模型将被用作拟议的定量机制研究的可操作性实验平台。将进行详细的机制研究，以阐明人类脊髓模型中的神经上皮细胞如何整合形态原信号的持续时间和水平，以调节不同数量和持续时间的关键转录效应器活动。此外，还将进行详细的机制研究，以了解关键转录效应器的动态细胞内活动如何与人类脊髓模型中神经元亚型的逐渐出现和命运规范相关。由于其跨学科的性质，拟议的研究将无缝地整合不同领域的知识，包括干细胞生物学、发育生物学、信号转导、上皮生物学和微流体学。这项研究中提出的机械性调查将提供新的基本知识和新的发现，即新兴的自组织原理和模式机制，为胚胎模式提供健壮性和可靠性，这是生物学中的一个长期问题，该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

During development of the nervous system, a vast array of neurons will develop in discrete positions, acquire varied shapes, and establish connections with specific populations of target cells. Such spatial organization of neuronal cell fates and differentiation are generally accepted as being directed by soluble chemical signals, termed morphogens. However, it remains a significant question in biology about how embryonic cells transform morphogen information into spatial patterns of neuronal cell differentiation during the nervous system development. This goal of this project is to specifically address this significant knowledge gap by leveraging a stem cell-based development model that has been established in the investigator's laboratory. This synthetic human development model will be used as a controllable experimental system to determine how different morphogen signals control intracellular activities of key signaling pathways to regulate neuronal cell fates. The project, if successful, will foster significant progress in advancing fundamental understanding of the nervous system development, which is important for diagnosis, prevention and treatment of neurological disorders that are the result of impaired development and growth of the nervous system. The technologies developed under this project will be used to enhance K-12 outreach activities, with priority given to females and minority students, and educational opportunities for undergraduate and graduate students. Outreach activities planned for students in the Ann Arbor and Ypsilanti school districts include developing a summer intern program for high school students and developing educational modules for NanoCamps and TECH DAY events for K-12 students. Established University of Michigan undergraduate research programs will be leveraged to recruit undergraduate students to participate in the lab's research and a new course on "Stem Cell Bioengineering and Biotechnology" will be developed to prepare graduate students for emerging areas such as regenerative medicine and disease modeling.It remains mysterious how embryonic cells transform dynamic changes in developmental signaling into spatial patterns of gene expression and cellular differentiation in a reliable and robust fashion. A fundamental goal of this project is thus to leverage recent progresses in human stem cell-based development models to study morphogen gradient-mediated embryonic patterning. Specifically, a synthetic microfluidic patterned human spinal cord model developed from human pluripotent stem cells will be leveraged as a maneuverable experimental platform for the proposed quantitative mechanistic investigations. Detailed mechanistic investigations will be conducted to elucidate how neuroepithelial cells in the human spinal cord model integrate the duration and level of morphogen signals to mediate distinct quantities and durations of key transcriptional effector activities. Furthermore, detailed mechanistic investigations will be conducted to understand how dynamic intracellular activities of key transcriptional effectors correlate with progressive emergence and fate specifications of neuronal subtypes in the human spinal cord model. Owing to its interdisciplinary nature, the proposed research will seamlessly integrate knowledge from distinct fields including stem cell biology, developmental biology, signal transduction, epithelial biology and microfluidics. The mechanistic investigations proposed in this research will provide new fundamental knowledge and novel discoveries of emergent self-organizing principles and pattering mechanisms that provide robustness and reliability to embryonic patterning, a long-standing question in biology,This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.