Alpha-helical peptide hydrogels as instructive scaffolds for 3D cell culture and tissue engineering

我们的研究关注的是了解生物学如何使用分子构建块来构建功能结构。我们将这一理解应用于使从分子中获得的新结构在实验室中可用。特别是，对于这项建议，我们感兴趣的是制造十亿分之一到百万分之一米的纤维结构。有了这样的“纳米纤维”，我们希望构建“水凝胶”--即99%为水的缠绕纤维网络。这些可以用来捕获有用的分子(如生长因子和营养物质)，然后在实验室中支持细胞和组织的生长。这些新的生物材料将在组织工程领域有长期的用途。我们的灵感来自生物学，它使用纤维材料在细胞内外制造具有各种功能的结构；例如，赋予细胞形状和稳定性；提供细胞内的分子高速公路；充当将细胞连接在一起的粘合剂，形成组织，即所谓的细胞外基质(ECM)。在我们提出的研究中，我们的目标是制造更简单的、或简化的和易于理解的材料，以捕捉ECM的关键特性和生物功能。我们对构建生物成分--蛋白质、细胞、组织等--的原理的理解还处于早期阶段；我们才刚刚开始挖掘这一知识的潜力。将生物的复杂性降低到原理和可管理的构件，然后将它们拼凑在一起形成新的材料和系统的努力被称为“合成生物学”。这是一门非常新的、令人兴奋的科学。然而，有一个问题：我们目前在这方面做得不是很好。自然的一个关键特征是，它使用“自组装”将其组件组装在一起--即，生物分子以某种方式被编程，以精确的方式相互作用和合作--这与我们目前构建日常技术的方式截然不同。我们感兴趣的是一种蛋白质，它能引导和粘合蛋白质链之间的相互作用。这被称为盘绕线圈。在其他方面，它负责制造像豪猪刺这样的结构。我们的利益下降了几个数量级，从十亿分之一米到百万分之一米的规模。我们已经在实验室里成功地制造了纤维结构，就像羽毛一样，达到了这种规模。最近，我们学会了如何使这些纤维更具弹性，结果是，它们相互作用并缠绕在一起，形成凝胶。我们的下一步，按照这里的建议，是：使纤维和凝胶更可靠、更便宜；改变它们的物理性质；用其他功能分子装饰它们；最终，测试细胞如何生长并对它们做出反应。这项提议的目的是汇集必要的专业知识，并创造工具来采取这些步骤。为什么要这么做？著名物理学家理查德·费曼曾经说过，他不能建造的东西，他就不懂。这是我们在研究中采用的原则：我们计划观察自然生物系统，从中学习，然后通过设计和尝试构建新的简化系统来测试我们的理解。这并不容易，而且存在失败的风险。然而，潜在的回报是高的：我们至少可以了解生物学的一些组成部分是如何组装的；然后我们和其他人可以利用这种理解来创造新的生物材料，这些材料最终可能会在其他基础科学和医学中得到应用。

Our research is concerned with understanding how biology builds functional structures using molecular building blocks. We apply this understanding to make new structures from molecules accessible in the lab. In particular, for this proposal, we are interested in making fibrous structures at the scale of billionths to millionths of a metre. With such 'nanofibres' in hand, we wish to construct 'hydrogels'-that is, entangled networks of fibres that are >99% water. These could be used to capture useful molecules (such as growth factors and nutrients), and then to support cell and tissue growth in the laboratory. These new biomaterials would have long-term uses in the area of tissue engineering. Our inspiration comes from biology, which uses fibrous materials to make structures with a wide variety of functions both within and outside cells; for instance, to give shape and stability to cells; to provide molecular highways within cells; and to act as the glue that hold cells together o form tissues, the so-called extracellular matrix (ECM). In our proposed research, we aim to make simpler, or stripped-down and well-understood materials that capture the key properties and biological functions of the ECM. It is early in the development of our understanding of the principles upon which biological components--proteins, cells, tissues etc--are built; and we are only just beginning to tap the potential of this knowledge. Endeavours to reduce biological complexity to principles and manageable building blocks, and then piece these together to form new materials and systems are known as 'synthetic biology'. This is a very new and exciting science. There's a catch, however: we're not very good at it at the moment. A key feature of Nature is that it uses 'self-assembly' to piece its components together--i.e., the biomolecules are somehow programmed to interact and cooperate in precise ways--which is very different from how our everyday technologies are currently built. We are interested in one type of protein that directs and cements interactions between protein chains. This is called the coiled coil. Amongst other things, it is responsible for making structures like porcupine quills. Our interests are down a few orders of magnitude at the scale of billionths to millionths of a metre. We have succeeded in making fibrous structures, like the quills, in the lab on this scale. Recently, we have learnt how to make these fibres more flexible, and, as result, they interact and entangle to make the gels. Our next steps, as proposed here, are: to make the fibres and gels more reliably and cheaply; to alter their physical properties; to decorate them with other functional molecules; and, ultimately, to test how cells grow on, and respond to them. The aim of this proposal is bring together the necessary expertise and create the tools to make these steps. Why do this? The famous physicist Richard Feynman once remarked that what he could not build, he did not understand. This is the principle that we have adopted for our research: we plan to look at natural biological systems, learn from them, and then test our understanding by designing and attempting to construct new simplified systems. This will not be easy and there is a risk of failure. However, the potential rewards are high: we stand to learn how some of biology's components assemble at the very least; and this understanding can then be applied by us and by others to create new biomaterials that might eventually find applications in other fundamental science and medicine.