A high-throughput-compatible animal-cell-free miniaturised thymic organoid model for thymus biology studies and in vitro T cell production.

T细胞是一种白细胞，是我们免疫系统的重要组成部分。它们协调并影响我们的免疫反应，这样我们就可以控制感染。控制不同的感染需要不同类型的免疫反应，我们的T细胞允许我们对特定的感染做出特定的免疫反应。最近，T细胞的力量已经在医学上被利用来制造一种被称为免疫疗法的新型疗法。免疫疗法仍处于初级阶段，但已经成功地用于治疗一些血癌。在体内，T细胞只能在高度专门化的器官--胸腺中产生。胸腺指示血液中的前体细胞成为T细胞，然后引导发育中的T细胞通过一系列筛选过程，确保只有安全、功能正常的T细胞离开胸腺成为免疫系统的一部分。这些过程是必需的，因为每个T细胞表面都有一种名为T细胞受体(TCR)的蛋白质。TCR识别并结合其他非T细胞表面的一小部分特定蛋白质(称为多肽)。当T细胞发育时，会产生大量不同的TCRs，每个TCRs识别来自不同蛋白质的一种肽。每个T细胞都有不同的TCR。一些制成的TCR可以结合来自病毒等感染性病原体蛋白质的多肽。其他TCR可以结合我们体内蛋白质中的多肽。如果这些“自我反应”的TCR成为我们免疫系统的一部分，它们会引起自身免疫，为了避免这种情况，它们会在胸腺中被筛选出来。这种筛选是由胸腺中称为胸腺上皮细胞的特殊细胞执行的，胸腺上皮细胞可以选择性地移除或解除“自我反应性”T细胞的武装。胸腺是健康人最早退化的器官之一，这导致免疫系统功能随着年龄的增长而普遍下降。这是随着年龄的增长，我们更容易受到新的感染的主要原因之一，如流感和Covid19。胸腺退化也会给需要骨髓移植(BMT)的成年患者带来问题。这是因为，在移植后，一些患者需要几年时间才能再次产生足够的T细胞，这些人仍然容易受到感染，直到他们的免疫系统得到适当重建。如果他们的胸腺功能能得到提高，这一时间就会缩短。所有这些都意味着在实验室里制造T细胞有很大的兴趣(例如。用于免疫治疗)，以及开发提高患者(包括骨髓移植患者和老年人)胸腺功能的方法，以提高他们对抗新感染的能力。然而，目前唯一能够很好地模拟胸腺功能以达到这些目的的实验模型依赖于从天然胸腺获得的细胞。胸腺组织稀少，难以处理，这严重限制了目前可以进行的研究的数量和规模-例如，目前无法高通量筛选与胸腺再生相关的新药。我们最近已经证明，胸腺上皮细胞可以在实验室中从干细胞开始制造。我们还表明，我们可以在实验室中从天然胸腺组织开始培养微型胸腺器官(MTO)。我们以一种适合低通量、中通量和高通量研究的格式制作这些MTO，包括药物筛选和基于实验室的T细胞生产。然而，它们的使用仍然受到组织供应的限制。这个项目将测试我们是否可以将这两种方法结合起来，从干细胞中制造完全不含动物细胞的MTO。如果成功，这种新的无动物细胞模型系统将显著减少研究中使用的动物数量。它还将使胸腺研究进入一个新时代，在这个时代，可以很容易地进行更大规模的实验，向包括制药业在内的广泛实验室开放这一领域。

T cells, a type of white blood cell, are an essential component of our immune system. They coordinate and effect our immune responses so we can control infections. Controlling different infections requires different types of immune response and our T cells allow us to make specific immune responses to specific infections. Recently, the power of T cells has been harnessed in medicine to make a new type of therapy called immunotherapy. Immunotherapies are still in their infancy, but have already been used successfully to treat some blood cancers.Within the body, T cells can only be made in a highly specialised organ, the thymus. The thymus instructs precursor cells in the blood to become T cells, then guides the developing T cells through a series of screening processes that ensure that only safe, functional T cells leave the thymus to become part of the immune system. These processes are needed because each T cell has on its surface a protein called T cell receptor (TCR). The TCR recognises and binds a small part of a specific protein (called a peptide) on the surface of other, non-T, cells. When T cells are developing, a very large number of different TCRs are made, that each recognise a peptide from a different protein. Each T cell has a different TCR. Some of the TCRs that are made can bind peptides from proteins from infectious agents such as viruses. Other TCRs can bind peptides from proteins in our own bodies. If these 'self-reactive' TCRs became part of our immune systems they would cause autoimmunity and to avoid this, they are screened out in the thymus. This screening is performed by special cells in the thymus called thymic epithelial cells, which can selectively remove or disarm 'self-reactive' T cells. The thymus is one of the first organs to degenerate in healthy individuals, and this contributes to a general decline in immune system function with age. This is one of the major reasons that as we get older we become more susceptible to new infections, such as flu and covid19. Thymus degeneration also causes problems for adult patients requiring a bone marrow transplant (BMT). This is because, after transplant, some patients take several years to make enough T cells again and these individuals remain vulnerable to infections until their immune system has been properly rebuilt. If their thymus function could be boosted, this time would be shortened.All of this together means there is a lot of interest in making T cells in the lab (eg. for immunotherapy) and in developing methods for boosting thymus function in patients (including BMT patients and the elderly), to increase their ability to fight new infections. However, at present, the only experimental models that mimic thymus function sufficiently well for these purposes rely on the use of cells obtained from the native thymus. Thymus tissue is scarce and hard to work with, which severely limits the numbers and size of studies that can currently be performed - for instance high throughput screening for new drugs relevant to thymus regeneration is not currently possible. We have recently shown that thymic epithelial cells can be made in the lab, starting from stem cells. We have also shown that we can grow miniaturized thymus organs (MTOs), in the lab, starting from native thymus tissue. We make these MTOs in a format that is suitable for low, medium and high throughput studies including drug screening and lab based T cell production. However, their use is still limited by tissue supply. This project will test whether we can combine these two approaches to make fully animal-cell-free MTOs from stem cells. If successful, this new animal-cell-free model system will significantly reduce the number of animals used in research. It will also enable a new era of thymus research in which much larger scale experiments can easily be performed, opening up this area to a wide range of laboratories including the pharmaceutical industry.