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

来自免疫系统的细胞有能力靶向并杀死其他不受欢迎的细胞，例如癌细胞。支持识别和杀死的一个关键机制是形成“免疫突触”--靶细胞和免疫细胞膜之间紧密接触的区域。在其他功能中，免疫突触能够将有毒化合物从免疫细胞局部和选择性地输送到靶细胞，导致靶细胞死亡。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。在现代癌症免疫疗法中，从患者身上提取的T细胞经过基因工程改造，在被重新引入体内之前，帮助它们针对患者患有的特定癌症。这些疗法已被证明非常成功，特别是对某些类型的血癌，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。受免疫细胞的作用启发，我们建议构建能够选择性和可控地形成“合成免疫突触”的“人工免疫细胞”，该突触针对癌细胞并向它们注入抗癌药物。如果成功，这些合成的类细胞制剂可以支持新的疗法，这些疗法代表了一种更具可扩展性和可持续发展的替代活细胞免疫疗法的疗法。我们将使用“人工细胞”这个术语来描述各种从头开始构建的全合成微型机器，借用生物学(蛋白质、脂膜)的积木，并用合成纳米结构补充它们。人工细胞可以作为更好地理解基本生物现象的模型系统，但通常是针对医疗保健中的特定问题而设计的，如诊断和治疗。与活的生物细胞相比，人工细胞更容易编程，制造成本更低，风险和伦理问题也更少。然而，人工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。通过拟议的研究项目，我们计划通过蛋白质工程和DNA纳米技术的结合来解决这一瓶颈，我们将使用这些技术来构建新的分子机器，以调节免疫突触的形成。蛋白质工程以天然蛋白质为起点，然后对其进行修饰以赋予新的功能。反过来，DNA纳米技术利用合成的核酸分子，如分子乐高积木，构建具有精确控制形状和功能的功能纳米机器。由脂类双层形成的模拟生物细胞膜的合成胶囊(囊泡)将构成人造细胞的底盘，该底盘将装饰有突触形成蛋白质/DNA机制，并包裹将被注射到癌细胞中的治疗剂。在这项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，然后使用模拟人体内发现的条件的“试管”实验，在体外对如此形成的试剂进行模型癌细胞测试。我们收集的关于人工细胞的稳定性及其选择性和有效靶向癌细胞的能力的信息将为后续的翻译研究提供信息，在这些研究中，我们将从动物模型开始，在体内测试人工治疗剂。

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.