Controlling Hematopoietic Lineage Commitment from ESC to Platelets

描述（由申请人提供）： 骨髓移植告诉我们，造血是由多能造血干细胞支持的，这些造血干细胞可以在整个生命过程中维持或重建各种血细胞谱系。尽管我们对谱系定型的理解有所进展，但这并没有转化为治疗谱系特异性血细胞减少症的改进方法。我们申请的目标是进一步了解谱系承诺，并利用这些知识来开发分子干预措施，将在体外和体内驱动造血向所需的谱系。由于移植后血小板减少症的临床重要性，该申请特别关注巨核细胞生成，并最大限度地发挥与我们在费城儿童医院的UOl合作伙伴的协同作用。为了实现这一目标，我们提出了一个多方面的计划，有4个目标，每个目标涉及两个或两个以上的调查员从FHCRC/UW财团。在目标1中，Fero、帕丁顿和Torok-Storb博士将生成小鼠、犬和人的干细胞至血小板通路中功能定义祖细胞的分子谱。这三种实验模型具有互补优势，可以采用综合方法，包括可预测临床结局的稳健临床前体内模型。在目标2中，这些相同的研究者将基因修饰限定的祖细胞以表达谱系阶段特异性报告物，用于高含量、高通量的siRNA筛选测定，以鉴定将控制祖细胞命运的微环境的变化。第三个目标是测试不同祖细胞亚群对条件激活信号分子的增殖和分化潜力。为此，Blau和Emery博士将使用信号分子衍生物，这些衍生物可以响应于称为二聚化化学诱导剂（CID）的小分子药物而被激活。在目标4中，Drs Kiem和Blau将利用血小板减少症的犬模型来测试目标2中鉴定的基因产物，以及目标3中扩增的细胞产物，以提高体内血小板计数。这些在犬模型中的体内研究将在高度相关的临床前模型中确定这些疗法的安全性和有效性

DESCRIPTION (provided by applicant): Marrow transplantation have taught us that hematopoiesis is supported by multipotent hematopoietic stem cells that can maintain or reconstitute the various blood cell lineages throughout life. Despite advances in our understanding of lineage commitment, this has not translated into improved approaches for treating lineage specific cytopenias. The goal of our application is to further our understanding of lineage commitment and use this knowledge to develop molecular interventions that will drive hematopoiesis toward desired lineages both in vitro and in vivo. The application is specifically focused on megakaryopoiesis, because of the clinical importance of post-transplant thrombocytopenia, and to maximize synergy with our UOl partners at Childrens Hospital of Philadelphia. Towards this goal we propose a multifaceted program with 4 Aims, with each aim involving two or more investigators from the FHCRC/UW Consortium. In Aim 1, Drs Fero, Paddington and Torok-Storb will generate molecular profiles of functionally defined progenitors in the stem cell to platelet pathway from mouse, dog, and man. These three experimental models have complementary strengths that allow for a comprehensive approach including a robust preclinical in vivo model that can predict clinical outcomes. In Aim 2 these same investigators will gene modify the defined progenitor cells to express lineage-stage-specific reporters for use in a high content, high through put siRNA screening assays to identify changes in the microenvironment that will control progenitor fate. A third Aim will test the proliferation and differentation potential of distinct progenitor subsets in response to conditionally activated signaling molecules. For this purpose Drs Blau and Emery will use signaling molecule derivatives that can be activated in response to small molecule drugs called chemical inducers of dimerization (CIDs). In Aim 4, Drs Kiem and Blau will exploit the canine model of thrombocytopenia to test gene products identified in Aim 2, and cell products expanded in Aim 3 to improve the platelet count in vivo. These in vivo studies in the dog model will establish the safety and efficacy of these therapies in a highly relevant preclinical model