Engineering the design of self-assembling, shear-thinning pentapeptide hydrogels to promote neural cell growth and differentiation

大脑是人类经验的中心，但社会对影响脑细胞生存和生长的许多因素知之甚少。水凝胶生物材料可以帮助解决这个问题，因为它们的行为像人体组织，使研究人员能够在简化的实验室环境中模拟健康、患病或受伤的组织，更好地了解人类健康。虽然水凝胶可以模拟各种各样的组织，但模拟脑组织的水凝胶对于培养来自大脑的细胞是有用的。这项提议旨在制造类似于人体组织的新型水凝胶，因为它们是由相同的原材料组成的，由天然氨基酸串在一起构成，制作简单且成本低廉。由这些氨基酸构建块制备的水凝胶看起来和行为都像脑组织，其行为由块和块模式的选择控制。正确的氨基酸序列可能会产生相互发现并自动组装成三维结构的块，就像设计师建造自己的微观城市一样。这些可互换的块可以以不同的形状聚集在一起，这决定了水凝胶的行为更像液体还是固体，以及它是否适合生长细胞。水凝胶的性质将在实验室和计算机模拟中进行研究，以创建和测试最佳的块组合。考虑到块的多功能性和它们组装的方式，这种策略有望产生一种新的水凝胶材料家族，这种材料可以在损坏后自动重建。最能模拟脑组织的水凝胶将用于指导脑源性细胞的行为和控制细胞生长。这项研究将通过实验室和课程活动培养学生在生物学、材料科学、计算机科学、工程和神经科学方面的能力，从而影响教育。针对贫困青年的有偿高中和大学实习项目将培养对工程的兴趣，提供研究技能，并通过研究和科学交流在不同的学生群体中积累经验。第2部分：技术概述实现功能肽生物材料的关键是理解控制组装、形态和生物相互作用的分子和宏观特征。本研究的重点是合理设计和研究一个新的多肽家族，这些多肽在细胞相容条件下组装成一个强大的细胞外基质（ECM）水凝胶，其结构和生物活性驱动细胞命运。该项目旨在开发一种新的短的、快速凝胶化的、自我修复的肽，以模拟各种各样的组织。使用短的5-氨基酸序列作为凝胶简化了合成并最大限度地提高了适应性。这些新多肽将解决现有的多肽水凝胶缺陷，即1)凝胶机制导致敏感细胞（如神经元和神经干细胞）存活率低，2)机械刚度低。提出的方法将涉及神经细胞的细胞兼容封装作为测试平台。为了改进设计和发现过程，计算框架将与实验方法相结合。这种设计策略可以改变生物材料的发展，并解决表征生物基质中发生的动态过程的挑战。计算模拟将提供对肽组装的理解，并更有效地识别和预测候选肽，这些候选肽将与细胞相容地组装成3D物理水凝胶。主要目标是创建、建模和表征在生理条件下凝胶化并驱动神经干细胞分化的肽。该研究项目的成果将包括有利于生理凝胶化的氨基酸序列，肽组装的原子分子动力学模型，以及适合神经细胞培养的顺应性动态基质。生理相关的水凝胶，按需凝胶将大大提高细胞培养和研究的便利性和有效性。该项目将为社会经济困难的学生创建一个全面的高中研究实习计划，并拓宽他们的职业和大学机会。作为该项目的一部分，PI将在生物材料合成、分子模拟、干细胞生物学和神经组织工程方面交叉培训博士生、勤工俭学的大学生和高中实习生。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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYThe brain is central to the human experience, but society poorly understands many of the factors that impact brain cell survival and growth. Hydrogel biomaterials can help address this problem because they behave like human tissues, allowing researchers to model healthy and diseased or injured tissue in a simplified lab setting and better understand human health. While hydrogels can emulate a wide variety of tissues, hydrogels that emulate brain tissue are useful to grow cells derived from the brain. This proposal aims to make new hydrogels similar to human tissue because they are composed of the same raw materials, built from natural amino acids strung together in blocks that are simple and cheap to make. Hydrogels prepared from these amino acid building blocks look and act like brain tissue with behavior controlled by the choice of block and block pattern. The right amino acid sequence may result in blocks that find each other and automatically assemble into a 3-dimensional structure, like a designer microscopic city which builds itself. These interchangeable blocks can come together in different shapes, determining whether the hydrogel behaves more like a liquid or a solid, as well as its suitability for growing cells. Hydrogel properties will be studied in the lab as well as in computer simulations to create and test the best possible block combinations. Given the versatility of blocks and ways in which they assemble, this strategy is expected to result in a new family of hydrogel materials that can automatically rebuild themselves after damage. The hydrogels that best mimic brain tissue will be used to guide the behavior of brain-derived cells and control cell growth. This research will impact education by training students in biology, materials science, computer science, engineering, and neuroscience through laboratory and curricular activities. An outreach program centered on paid high school and college internships for underprivileged youth will nurture interests in engineering, provide research skills, and build experience in diverse student groups through research and science communication.PART 2: TECHNICAL SUMMARYIntegral to realizing functional peptide biomaterials is an understanding of the molecular and macroscopic features that govern assembly, morphology, and biological interactions. This research centers on the rational design and investigation of a new family of peptides that assemble under cytocompatible conditions into a robust extracellular matrix (ECM) hydrogel with structure and bioactivity that drive cell fate. This project seeks to develop a new family of short, rapidly gelling, self-healing peptides that emulate a wide variety of tissues. Using short, 5-amino-acid sequences as gelators simplifies synthesis and maximizes adaptability. These new peptides will address existing peptide hydrogel deficiencies, namely 1) gelation mechanisms that lead to poor survival of sensitive cells, like neurons and neural stem cells, and 2) low mechanical stiffnesses. The proposed approach will involve cytocompatible encapsulation of neural cells as a test bed. To improve the design and discovery process, a computational framework will be integrated with the experimental approach. This design strategy could transform biomaterials development and address the challenges of characterizing the dynamic processes that occur in biological matrices. Computational simulations will provide understanding of peptide assembly and more efficiently identify and predict peptide candidates that will cytocompatably assemble into 3D physical hydrogels. The primary goal is to create, model, and characterize peptides that gel under physiological conditions and drive neural stem cell differentiation. Outcomes of this research project will include amino acid sequences conducive to physiological gelation, an atomistic molecular dynamic model of peptide assembly, and a compliant, dynamic matrix appropriate for neural cell culture. Physiologically relevant hydrogels that gel on-demand will dramatically improve the ease and efficacy of cell culture and study. This project will create a comprehensive high school research internship program for socioeconomically challenged students, and broaden their career and college opportunities. As part of this project the PI will cross train PhD students, work-study college students, and high school interns in biomaterials synthesis, molecular simulations, stem cell biology, and neural tissue engineering.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.