Methods for Producing T lymphocytes in vitro from Stem Cells

T淋巴细胞之所以被称为T淋巴细胞，是因为它们在胸腺中发育，是一种对免疫系统功能至关重要的白细胞。这些细胞的功能异常与免疫缺陷(如艾滋病)或自身免疫(如I型糖尿病、类风湿性关节炎)有关。T淋巴细胞来自血液干细胞，并在胸腺中完成成熟，胸腺是位于心脏附近的一个器官，专门进化来提供促进T细胞发育的环境。造血干细胞在成熟为T淋巴细胞时所经历的发育阶段已经得到了相对较好的描述。这使得能够识别关键的监管检查点，细胞为了进一步发展必须通过这些检查点。其中一个检查点被称为测试版选择。为了通过这个检查点，细胞必须产生特定的信号，这些信号会导致基因表达的变化，并允许细胞分裂和分化。T细胞发育的体外模型依赖于来自支持基质细胞的辅助因子，其中Notch-1配体是最了解的。然而，Notch-1配体不足以在没有辅助细胞的情况下允许T细胞发育，这表明需要由基质细胞产生额外的因子。我们已经确定趋化因子CXCL12是β-选择过程中的一个辅助因子，这使得我们能够创建一个允许β-选择的无辅助细胞培养系统。我们现在建议检查额外的基质衍生成分，如层粘连蛋白和Wnt在无细胞系统中的作用。我们还建议测试我们对胸腺细胞发育的洞察力是否会允许干细胞在不需要基质辅助细胞的情况下生长T细胞。这将提供一个更简单的系统来评估分化的分子过程。此外，它可能允许T细胞的扩增，用于再生医学领域的基于细胞的治疗。

T lymphocytes, so-called because they develop in the thymus, are a type of white blood cell crucial for the function of the immune system. Aberrant function of these cells is associated with immunodeficiency (e.g. AIDS) or autoimmunity (e.g. type I diabetes, rheumatoid arthritis). T lymphocytes are derived from blood stem cells and complete their maturation in the thymus, an organ located near the heart that has evolved specifically to provide an environment that promotes T cell development. The developmental stages haematopoietic stem cells pass through as they mature into T lymphocytes have been relatively well-characterised. This has allowed the identification of key regulatory checkpoints that cells must pass through in order to develop further. One of these checkpoints is called beta-selection. In order to pass through this checkpoint cells must generate specific signals which bring about changes in gene expression and allows the cells to divide and differentiate. In vitro models of T cell development rely on accessory factors derived from supporting stromal cells of which Notch-1 ligands are the best understood. However Notch-1 ligand is insufficient to allow T cell development in the absence of accessory cells indicating additional factors produced by the stromal cells are required. We have identified the chemokine CXCL12 as a co-factor in the process of beta-selection and this has enabled us to create an accessory cell free culture system which is permissive for beta-selection. We now propose to examine the effect of additional stromal derived components such as laminin and Wnt for their effect in a cell-free system. We also propose to test whether our insight into the development of thymocytes will permit the growth of T cells from stem cells without the need for stromal accessory cells. This will provide a simpler system to evaluate the molecular processes of differentiation. Furthermore, it may permit the expansion of T cells for cell-based therapy in the area of regenerative medicine.