EPSRC New Horizons 2021: Engineering synthetic synapses between artificial and biological cells.

来自免疫系统的细胞有能力瞄准并杀死其他不需要的细胞，例如癌细胞。支持识别和杀伤的关键机制是“免疫突触”的形成，这是目标细胞和免疫细胞膜之间密切接触的区域。在其他功能中，免疫突触使有毒化合物能够从免疫细胞局部和选择性地传递到目标细胞，导致目标细胞死亡。除了在自然免疫反应中发挥关键作用外，被称为T细胞的免疫细胞构成了现代癌症免疫疗法的基础，从患者身上提取的T细胞经过基因工程改造，以帮助它们靶向患者患有的特定癌症，然后再重新引入体内。这些疗法已被证明是非常成功的，特别是对于某些类型的血癌，但它们的广泛应用受到对患者细胞进行基因工程相关的技术挑战的阻碍，这导致医疗保健系统的成本非常高。受免疫细胞作用的启发，我们提出构建“人工免疫细胞”，能够选择性地、可控地形成“合成免疫突触”，靶向癌细胞并向其注射抗癌药物。如果成功的话，这些合成细胞样药物可以作为新疗法的基础，代表了一种更可扩展和可持续的替代活细胞免疫疗法。用“人造细胞”这个术语，我们描述了各种各样的完全合成的微型机器，它们从零开始构建，借用生物学的构建模块（蛋白质、脂质膜），并用合成的纳米结构来补充它们。人造细胞可以作为模型系统来更好地理解基本的生物现象，但通常是针对医疗保健中的特定问题而设计的，例如诊断和治疗。与活的生物细胞相比，人造细胞更容易编程，制造成本更低，风险和伦理问题也更少。然而，人造细胞仍然无法复制生物细胞的一些高度复杂的行为，包括靶向和杀死癌细胞的能力。在这个研究项目中，我们计划通过蛋白质工程和DNA纳米技术的结合来解决这个瓶颈，我们将用它来构建介导免疫突触形成的新分子机器。蛋白质工程是以天然蛋白质为起点，对其进行修饰，赋予其新的功能。反过来，DNA纳米技术利用合成的核酸分子，就像分子乐高积木一样，来构建具有精确控制形状和功能的功能性纳米级机器。由脂质双层和模拟生物细胞的膜形成的合成胶囊（囊泡）将构成人工细胞的底盘，它将被突触形成的蛋白质/DNA机制装饰，并封装治疗剂注射到癌细胞中。在这个初步的概念验证研究中，我们将构建和优化蛋白质和DNA机制，并为人造细胞配备它，然后在体外模型癌细胞上测试这种形成的药物，使用“试管”实验来模拟体内发现的条件。我们收集的关于人造细胞的稳健性及其选择性有效靶向癌细胞的能力的信息将为后续的转化研究提供信息，在这些研究中，我们将从动物模型开始在体内测试人造治疗剂。

Cells from the immune system have the ability to target and kill other undesirable cells, for instance cancer cells. A key mechanism underpinning recognition and killing is the formation of an "immune synapse" - a region of close contact between the membranes of the target and immune cell. Among other functions, the immune synapse enables localised and selective delivery of toxic compounds from the immune cell to the target cell, leading to death of the target. Besides playing a critical role in the natural immune response, immune cells known as T cells form the basis of modern cancer immunotherapies, where T cells extracted from the patients are genetically engineered to help them target the specific cancer the patient has, before being reintroduced in the body. These therapies have proven very successful, particularly for some types of blood cancer, but their broad application is hindered by the technical challenges associated to performing genetic engineering on patient cells, which results in very high costs for healthcare systems.Inspired by the action of immune cells here we propose to construct "artificial immune cells" able to selectively and controllably form "synthetic immune synapses", which target cancer cells and inject them with anti-cancer drugs. If successful, these synthetic cell-like agents could underpin novel therapies that represent a more scalable and sustainable alternative to live-cell immunotherapies.With the term "artificial cell" we describe a broad variety of fully synthetic micromachines constructed from scratch, borrowing building blocks from biology (proteins, lipid membranes) and complementing them with synthetic nanostructures. Artificial cells can serve as model systems to better understand basic biological phenomena but are often designed to target specific problems in healthcare, such as diagnostics and therapeutics. Compared to live biological cells, artificial cells are easier to program, cheaper to manufacture and carry fewer risks and ethical concerns. However, artificial cells are still unable to replicate some of the highly complex behaviours of biological cells, including the ability to target and kill cancer cells. With the proposed research project, we plan to tackle this bottleneck through a combination of protein engineering and DNA nanotechnology, which we will use to construct new molecular machines that mediate immune synapse formation. Protein engineering takes natural proteins as the starting point, and then modifies them to impart new functionalities. DNA nanotechnology, in turn, utilises synthetic nucleic acid molecules like molecular Lego bricks, to construct functional nanoscale machines with precisely controlled shape and functionality. Synthetic capsules (vesicles) formed from lipid bilayers and mimicking the membrane of biological cells will constitute the chassis of the artificial cells, which will be decorated with the synapse forming protein/DNA machinery and encapsulate the therapeutic agent to be injected in the cancer cell.For this initial proof-of-concept study we will construct and optimise the protein and DNA machinery and equip the artificial cells with it, before testing the so-formed agents on model cancer cells in vitro, using "test tube" experiments that mimic the conditions found in the body. The information we gather on the robustness of the artificial cells and their ability to target cancer cells selectively and effectively will inform subsequent translational studies in which we will test the artificial therapeutic agents in vivo, starting with animal models.