Designing cell-instructive hydrogels to understand and exploit mechanobiology

摘要 依赖于锚定的细胞通过拉和推它们周围的细胞来感知周围的力学 细胞外基质(ECM)，并作为响应，在一个称为 机械转导。基质的机械性能调节一系列细胞行为，如牵引力 世代、细胞骨架组织、增殖、迁移和分化，需要 开发体外模型系统来研究和理解这些细胞现象。我的实验室在 将水凝胶设计为体外模型的前沿，它摆脱了静态的、整体的结构和 向动态、交互和响应性强的材料发展，这些材料捕捉到了本地蜂窝环境的复杂性。 拟议的研究方案将解决理解和开发领域的一个关键瓶颈。 细胞机械转导的机械知识有助于解决疾病和疾病中的健康挑战 组织再生。主题1：依赖时间的力学如何影响细胞 机械转导？虽然几乎所有的合成生物材料都呈现出弹性的机械环境 细胞，大多数天然的ECM材料是粘弹性的，并表现出复杂的随时间变化的力学行为。 对允许合成材料设计灵活性的细胞培养平台的需求仍然没有得到满足 (例如，配体呈现和刚性的时空调谐)，同时还显示粘弹性力学 属性。这一研究主题将建立在我的团队开发粘弹性的蓬勃发展的努力之上 水凝胶，以测试在3D培养中粘弹性，而不是基于硬度的信号，是 成纤维细胞活化和间充质基质细胞中主动机械转导所需的主导因子 (MSC)分化。主题2：机械学如何调节生长因子信号转导？而当 最近的整体研究探索了刚性、配体呈递和降解对茎的影响。 细胞的增殖和分化，对这些特性如何促进转化生长知之甚少 转化生长因子-β(Fel-β)的信号转导。通过考察底物生物物理和微生物的联合影响 生化特性，这个主题将阐明细胞微环境如何影响细胞的设计规则 生长因子信号转导的机制生物学，从而为生物材料的设计提供了框架 这使得能够更有效地展示增长因素。主题3：我们能设计温度响应型计算机吗 干细胞维持和扩增的生物材料？高效地生成大量数字的能力 特定的、明确的细胞类型对于治疗许多疾病和障碍至关重要。这个主题 将专注于创造热敏可调生物材料，以优化扩展、维护、 以及对MSCs进行机械启动，同时还可以方便地获取和验证细胞。多层次的 刺激响应性将被设计(例如，通过包括液晶域)以允许 在培养和随后的细胞释放过程中的机械驱动，用于下游应用。

ABSTRACT Anchorage-dependent cells sense the mechanics of their surroundings by pulling and pushing on the extracellular matrix (ECM), and in response, generate intracellular signals in a process known as mechanotransduction. Matrix mechanical properties regulate a range of cell behaviors such as traction force generation, cytoskeletal organization, proliferation, migration, and differentiation, necessitating the development of in vitro model systems to investigate and understand these cellular phenomena. My lab is at the forefront of designing hydrogels as in vitro models that move away from static, monolithic constructs and toward dynamic, interactive, and responsive materials that capture the complexity of native cellular milieus. The proposed research program will address a critical bottleneck in the field of understanding and exploiting mechanistic knowledge of cellular mechanotransduction toward addressing health challenges in disease and tissue regeneration. Theme 1: How Do Time-Dependent Mechanics Affect Cellular Mechanotransduction? While nearly all synthetic biomaterials present an elastic mechanical environment to cells, most natural ECM materials are viscoelastic and exhibit complex time-dependent mechanical behavior. There is still an unmet need for cell culture platforms that permit the design flexibility of synthetic materials (e.g., spatiotemporal tuning of ligand presentation and stiffness) while also displaying viscoelastic mechanical properties. This research theme will build on burgeoning efforts from my group to develop viscoelastic hydrogels in order to test the hypothesis that in 3D cultures viscoelasticity, not stiffness-based signaling, is the overriding factor required for active mechanotransduction in fibroblast activation and mesenchymal stromal cell (MSC) differentiation. Theme 2: How Do Mechanics Regulate Growth Factor Signal Transduction? While recent integral studies have explored the influence of stiffness, ligand presentation, and degradation on stem cell proliferation and differentiation, little is known about how these properties contribute to transforming growth factor-β (TGF-β) signal transduction. By investigating the combined influence of substrate biophysical and biochemical properties, this theme will elucidate design rules for how cellular microenvironments influence the mechanobiology of growth factor signal transduction, thus providing a framework for the design of biomaterials that permit more efficient presentation of growth factors. Theme 3: Can We Engineer Thermoresponsive Biomaterials for Stem Cell Maintenance and Expansion? The ability to efficiently generate large numbers of specific, well-defined cell types is critical to the treatment of numerous diseases and disorders. This theme will focus on the creation of thermoresponsive tunable biomaterials to optimize the expansion, maintenance, and mechanical priming of MSCs, while also enabling facile cell harvesting and validation. Multiple levels of stimuli-responsiveness will be engineered (e.g., through inclusion of liquid crystalline domains) to permit both mechanical actuation during culture and subsequent cell release for use in downstream applications.