Patterned Synthetic Spinal Cords from Human Pluripotent Stem Cells

在神经系统的发育过程中，大量的神经元会在离散的位置发育，获得不同的形状，并与特定的目标细胞群建立联系。神经细胞命运和分化的这种空间组织通常被认为是由称为形态因子的可溶性化学信号指导的。然而，在神经系统发育过程中，胚胎细胞如何将形态信息转化为神经元细胞分化的空间模式，仍然是生物学中一个重要的问题。该项目的目标是通过利用研究者实验室建立的基于干细胞的发展模型来专门解决这一重要的知识差距。这个合成的人类发育模型将作为一个可控的实验系统来确定不同的形态素信号如何控制关键信号通路的胞内活动，从而调节神经元细胞的命运。该项目如果成功，将在推进对神经系统发育的基本理解方面取得重大进展，这对于神经系统发育和生长受损导致的神经系统疾病的诊断、预防和治疗非常重要。在这个项目下开发的技术将用于加强K-12的外联活动，优先考虑女性和少数民族学生，并为本科生和研究生提供教育机会。为安娜堡和伊普斯兰蒂学区的学生计划的外展活动包括为高中生开发暑期实习项目，为K-12学生开发纳米夏令营和TECH DAY活动的教育模块。现有的密歇根大学本科生研究项目将被利用来招募本科生参与实验室的研究，并将开发一门名为“干细胞生物工程和生物技术”的新课程，为研究生在再生医学和疾病建模等新兴领域做好准备。胚胎细胞如何以可靠和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梯度介导的胚胎模式。具体来说，由人类多能干细胞开发的合成微流体模式人类脊髓模型将被用作拟议定量机制研究的可操作实验平台。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素信号的持续时间和水平，以介导关键转录效应物活性的不同数量和持续时间。此外，将进行详细的机制研究，以了解关键转录效应物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。由于其跨学科性质，拟议的研究将无缝整合来自不同领域的知识，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。本研究提出的机制研究将为新兴的自组织原理和模式机制提供新的基础知识和新发现，为胚胎模式提供鲁棒性和可靠性，这是生物学中一个长期存在的问题。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力价值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.