Understanding Multi-stage Neural Stem Cell Function via 4D Bioprinting Reprogrammable System

神经损伤是全世界最常见和最具破坏性的临床挑战之一。目前，基于干细胞的技术在治疗神经损伤方面显示出巨大的前景。然而，成功地将干细胞用于临床应用的主要挑战之一是难以提供适当的环境线索来调节它们的行为。目前大多数可用于指导干细胞行为的技术利用简单的2D或3D微环境，这些微环境在本质上基本上是静态的，因此无法反映干细胞在其中发育的自然神经组织环境的动态性质。因此，本研究的目的是开发一种新型的4D(时间是第4维)打印智能系统，该系统可以随着时间的推移改变其形状，以改善神经干细胞(NSC)的功能和神经再生。本研究将阐明神经干细胞在动态环境中发育和分化的基本机制。此外，4D生物打印系统将在组织/器官再生、体外药物筛选和疾病建模等许多潜在应用中具有广阔的应用前景。综合研究、教育和外联活动将特别重视不同层次的代表性不足的少数民族和女学生，并将为不同的受众提供高素质的科学和工程教育。本项目的目标是打印一种新型的可重编程的智能系统，该系统具有随时间变化的动态转换，可以提供一种有效的手段来迎合神经干细胞经历的不同神经发育阶段，并将促进神经组织的再生。4D生物打印系统可以提供完美的自我变形功能，当暴露在预定的刺激下时，可以控制NSC的命运。为此，将进行两个具体的研究目标：目标1将主要专注于合成可重新编程的4D墨水材料，这种材料可以在生理温度下执行两周的形状变化。4D油墨将通过改变不同油墨成分的比例来配制，以获得所需的、可打印的流变性。目标2将涉及智能神经结构的生物打印，并将探索神经干细胞在4D转化过程中的功能和生物力学。将对生物打印构建物的微观结构和机械性能进行表征。此外，在4D动态环境的背景下，神经干细胞的分化、轴突延伸和基因表达将在体外进行彻底的评估。该项目的成功完成将提供一个革命性的智能系统，用于提高神经再生用途的NSC的性能。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。

Neural injuries represent one of the most common and devastating clinical challenges worldwide. Currently, stem cell-based technologies have shown great promise in treating nerve damage. However, one of the major challenges in successfully utilizing stem cells for clinical applications is the difficulty in providing proper environmental cues to regulate their behaviors. Most of the currently available techniques to guide stem cell behavior utilize simple 2D or 3D microenvironments, which are largely static in nature, and therefore fail to reflect the dynamic nature of the native neural tissue environment in which stem cells develop. Thus, the objective of this study is to develop a novel 4D (time being the 4th dimension) printed smart system, which can change its shape over time in order to improve neural stem cell (NSC) function and neural regeneration. This study will elucidate the fundamental mechanisms of NSC development and differentiation in a dynamic environment. Furthermore, the 4D bioprinting system will be promising for many potential applications ranging from tissue/organ regeneration to in vitro drug screening and disease modeling. Integrated research, educational, and outreach activities will place special emphasis on underrepresented minorities and female students at different levels, and will provide a diverse audience with a high-caliber science and engineering education. The goal of this project is to 4D print a novel reprogrammable smart system with a time-dependent dynamic transformation, which can provide an efficient means to cater to the different neurodevelopmental stages undergone by NSCs and will improve neural tissue regeneration. The 4D bioprinting system can provide a perfect self-morphing feature when exposed to a predetermined stimulus for controlling NSC fate. For this purpose, two specific study aims will be performed: Aim 1 will primarily focus on synthesizing reprogrammable 4D ink materials, which can execute a two-week shape change at physiological temperature. The 4D inks will be formulated by varying the ratios of different ink components in order to achieve desirable, printable rheological properties. Aim 2 will involve the bioprinting of smart neural constructs and will explore NSC functions and biomechanics during the 4D transformation process. The microstructure and mechanical properties of the bioprinted constructs will be characterized. Furthermore, NSC differentiation, axonal extension, and gene expression within the context of the 4D dynamic environment will be thoroughly evaluated in vitro. The successful completion of the project will provide a revolutionary smart system for enhancing the performance of NSCs for neural regeneration purposes.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.