Designing cell-instructive hydrogels to understand and exploit mechanobiology

摘要 锚定依赖性细胞通过对周围环境的推拉来感知周围环境的力学。 细胞外基质（ECM），并作为响应，产生细胞内信号的过程称为 机械传导基质的力学性质调节着细胞的一系列行为，如牵引力 生成，细胞骨架组织，增殖，迁移和分化，需要 开发体外模型系统以研究和理解这些细胞现象。我的实验室在 设计水凝胶作为体外模型的最前沿，远离静态的整体结构， 朝着动态的，互动的，和响应材料，捕捉天然细胞环境的复杂性。 拟议的研究计划将解决一个关键的瓶颈领域的理解和利用 细胞机械转导的机械知识，以应对疾病和 组织再生主题1：时间依赖机制如何影响细胞 机械传导？尽管几乎所有合成生物材料都呈现弹性力学环境， 细胞，大多数天然ECM材料是粘弹性的，并表现出复杂的时间依赖性机械行为。 仍然存在对允许合成材料的设计灵活性的细胞培养平台的未满足的需求 (e.g.,配体呈递和刚度的时空调节），同时还显示粘弹性机械 特性.这个研究主题将建立在我的小组迅速发展的努力， 水凝胶，以测试假设，在3D文化的粘弹性，而不是基于刚度的信号，是 成纤维细胞活化和间充质基质细胞中主动机械传导所需的主导因子 (MSC)分化主题2：力学如何调节生长因子信号转导？而 最近的综合研究已经探索了刚度、配体呈递和降解对茎的影响， 细胞增殖和分化，很少有人知道这些属性如何有助于转化生长 TGF-β信号转导。通过研究底物生物物理和 生物化学特性，这个主题将阐明细胞微环境如何影响生物化学特性的设计规则。 生长因子信号转导的机械生物学，从而为生物材料的设计提供了框架 其允许更有效地呈递生长因子。主题3：我们可以设计热响应吗？ 用于干细胞维持和扩增的生物材料？有效生成大量数据的能力 特定的、明确定义的细胞类型对许多疾病和病症的治疗至关重要。这个主题 将专注于创造热响应可调生物材料，以优化扩张，维护， 和MSC的机械引发，同时还能够容易地进行细胞收获和验证。多个级别的 将设计刺激响应性（例如，通过包含液晶域）， 在培养过程中的机械驱动和随后的细胞释放用于下游应用。

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.