Live imaging to determine the behavior of endogenous hematopoietic stem cells

 描述(申请人提供)：从发育的最早阶段开始，血管和神经形成在一起，并连接遥远的造血部位。随着我们了解更多，我们发现血细胞与神经元共享许多信号通路。我们开始明白，血液和神经系统之间存在沟通。我们现在知道，交感神经系统(SNS)支配着一个特殊的微环境，称为利基，是造血干细胞(HSCs)的家园。交感神经元发出的一个信号是去甲肾上腺素，它与基质支持细胞和造血干细胞本身上的β-肾上腺素能受体结合。这个信号指示基质细胞下调配体CXCL12，这是利基细胞最重要的保留信号之一，表达同源受体CXCR4。然后，造血干细胞被释放到循环中，或从骨髓中“动员”出来。这种动员和植入回利基的循环每天都受到SNS的调节，并遵循昼夜节律。最近，由于交感神经损伤可导致某些血液疾病的进展，骨髓龛神经支配的功能意义已变得明显起来。许多骨髓增生性肿瘤患者患有带有JAK2(V617F)突变的HSC，该突变驱动白细胞介素1的产生。过度产生这种细胞因子的HSC实际上会在利基内造成SNS损伤，最终加速疾病(Arranz等人。《自然》2014)。本研究计划的目标是了解神经系统对HSC生态位调节的机制，并寻找新的HSC及其生态位的神经调节因子。斑马鱼和老鼠将作为互补的模式生物。新的针对HSC的转基因技术和高分辨率显微镜已将斑马鱼确立为一个重要的HSC生态位模型(Tantin等人。单元格2014)。斑马鱼和哺乳动物之间的高度保护意味着研究结果很容易翻译。这项研究的目标是重建一个体外调节环境，允许在临床移植之前扩大和维持HSC。我的长期职业目标是在一家大型研究机构领导我自己的生物医学研究小组。我在发育遗传学和斑马鱼造血方面的博士后培训方面的深厚背景为这项拟议的研究做了极好的准备。我非常幸运地在波士顿儿童医院和哈佛医学院找到了理想的培训环境。我的导师伦纳德·I·宗博士非常支持我的研究，并正在帮助我为过渡到独立研究员做准备。我受益于在实验室指导哈佛大学的研究生和本科生，以及三名技术人员。我的合作导师乔治·Q·戴利博士、查尔斯·林博士和克里斯托弗·A·沃尔什博士分别在哺乳动物的HSC分析、HSC生态位的实时成像和神经生物学方面提供了他们的专业知识。这一奖项将使我在开始自己的独立研究计划之前，继续得到他们的指导和支持，该计划将探索造血系统和神经系统之间的接口。

 DESCRIPTION (provided by applicant): From the earliest stages of development, blood vessels and nerves form together and connect distant sites of hematopoiesis. As we learn more, we are finding that blood cells share many signaling pathways with neurons. We are beginning to understand that there is communication between the blood and nervous systems. We now know that the sympathetic nervous system (SNS) innervates a specialized microenvironment called the niche that is home to hematopoietic stem cells (HSCs). One signal from sympathetic neurons is norepinephrine that is bound by ß-adrenergic receptors on stromal support cells and HSCs themselves. This signal instructs stromal cells to down-regulate the ligand CXCL12, one of the most important retention signals for HSCs in the niche, which express the cognate receptor CXCR4. HSCs are then released into circulation or "mobilized" out of the bone marrow. This cycle of mobilization and engraftment back into the niche is regulated daily by the SNS and follows circadian rhythms. The functional significance of bone marrow niche innervation has recently become apparent, as sympathetic nerve damage can contribute to the progression of some blood diseases. Many patients with myeloproliferative neoplasms have HSC with a JAK2(V617F) mutation that drives interleukin-1 ß production. HSCs that overproduce this cytokine actually cause SNS injury within the niche that ultimately accelerates the disease (Arranz et al. Nature 2014). The goal of this research plan is to understand the mechanisms of HSC niche regulation by the nervous system and to find new neuroregulators of HSCs and the niche. The zebrafish and mouse will be used as complementary model organisms. Novel HSC-specific transgenics and high resolution microscopy has established the zebrafish as an important HSC niche model (Tamplin et al. Cell 2014). The high degree of conservation between zebrafish and mammals means findings can be easily translated. The goal of this research is to recreate a regulatory environment ex vivo that will allow expansion and maintenance of HSC prior to clinical transplantation. My long-term career goal is to lead my own biomedical research group at a major research institution. My strong background in developmental genetics and postdoctoral training in zebrafish hematopoiesis has been excellent preparation for this proposed research. I have been very fortunate to find an ideal training environment at Boston Children's Hospital and Harvard Medical School. My mentor Dr. Leonard I. Zon is highly supportive of my research and is helping me prepare for the transition to independent investigator. I have benefited from mentoring Harvard graduate and undergraduate students in the lab, and three technicians. My co-mentors Drs. George Q. Daley, Charles Lin, and Christopher A. Walsh have offered their expertise in the topics of mammalian HSC assays, live imaging of the HSC niche, and neurobiology, respectively. This award will allow me to continue receiving their guidance and support before starting my own independent research program that will explore the interface between the hematopoietic and nervous systems.