REGULATION OF LYMPHOPOIESIS FROM PLURIPOTENT STEM CELLS

虽然谱系定向造血细胞的分化阶段已被很好地表征，但从人淋巴造血干细胞（LHSC）分化的第一步产生的最早祖细胞的鉴定和调控仍然未知。最近发展的原始淋巴祖细胞的体外试验，现在允许直接研究人类LHSC的早期淋巴承诺期间的事件。我们假设：（1）人淋巴样分化通过两种可能的途径进行，即通过共同类淋巴样祖细胞（CLP）（其缺乏髓样和红细胞样潜能）和/或通过B淋巴-髓样祖细胞（BMP）（其缺乏髓样和红细胞样潜能）和/或通过B淋巴-髓样祖细胞（BMP）（其缺乏T淋巴和红细胞样潜能）。这些祖细胞阶段可以使用免疫表型标记物前瞻性地鉴定，和（2）产生鼠和人淋巴样祖细胞的增殖和分化受三种细胞因子受体信号通路协调调节：白细胞介素-7受体α（IL-R α）/共同γ链（γ/c）复合物; IL-R α/胸腺基质衍生的造血蛋白受体（TSLP-R）复合物;和IL-3R α/共同β链（β/c）复合物。该建议的具体目的是（1）免疫表型地确定人LHSC分化为淋巴样细胞的祖细胞阶段，（2）表征免疫表型和功能上确定的人LHSC和淋巴样祖细胞群体中的差异基因表达，和（3）确定如何通过IL-7 R α和IL-3 R α介导的途径调节鼠和人LHSC的淋巴样分化和增殖。这些研究将使用我们实验室开发的平行和互补的体外和体内系统进行，以研究小鼠和人淋巴造血。

Although the differentiation stages in lineage committed hematopoietic cells are well characterized, the identify and regulation of the earliest progenitors produced from the first steps in differentiation of human lympho-hematopoietic stem cells (LHSC) remain unknown. The recent development of in vitro assays for primitive lymphoid progenitors now permits the direct study of events during early lymphoid commitment for human LHSC. We hypothesize that: (1) human lymphoid differentiation proceeds through two possible pathways, through Common Lymphoid Progenitors (CLP) (which lack myeloid and erythroid potential) and/or through B lympho-Myeloid Progenitors (BMP) (which lack myeloid and erythroid potential) and/or through B lympho-Myeloid Progenitors (BMP) (which lack T lymphoid and erythroid potential). These progenitor stages can be identified prospectively using immunophenotypic markers, and (2) the production (i.e. proliferation and differentiation) of murine and human lymphoid progenitor cells is coordinately regulated by three cytokine receptor signaling pathways: the Interleukin-7 Receptor alpha (IL-Ralpha)/Common gamma chain (gamma/c) complex; the IL- Ralpha/Thymic Stroma Derived Lymphopoietic Protein-Receptor (TSLP- R) complex; and the IL-3Ralpha/Common beta chain (beta/c) complex. The Specific Aims of this proposal are to (1) determine immunophenotypically the progenitor stages through which human LHSC differentiate into lymphoid cells, (2) characterize the differential gene expression in immunophenotypically and functionally defined populations of human LHSC and lymphoid progenitors, and (3) determine how lymphoid differentiation and proliferation from murine and human LHSC are regulated through the IL-7Ralpha and IL-3Ralpha mediated pathways. These studies will be performed using parallel and complementary in vitro and in vivo systems developed in our laboratories to study murine and human lympho-hematopoiesis.