Improving the interaction of hematopoietic stem cells with the perivascular niche to promote engraftment

项目摘要/摘要 造血干细胞和祖细胞(HSPC)移植是许多血液疾病的根治方法 和癌症。然而，这些程序仍然需要优化，以改善患者的预后和存活率。 HSPC居住在一个被帮助调节其功能的利基细胞包围的微环境中。我们的研究 该提案旨在解决有关HSPC和生态位之间的细胞相互作用的基本问题 细胞。在胚胎发育过程中，HSPC穿过不同的组织并发生变化 与微环境接触的要求。HSPC最早出现在背主动脉，这是 胚胎，然后释放到循环中。接下来，HSPC迁移到胎儿肝脏，在那里 单元格通过对称分割以指数方式扩展。最后，HSPC再次迁移到骨髓中定居 在那里他们将在成年后一直待在那里。当HSPC在这些不同的造血系统之间迁移时 除了组织，它们也变得更加成熟，并被编程为成年静止状态。我们用 斑马鱼和老鼠作为与人类高度保守的模型系统，拥有许多用于 细胞行为的功能测试和实时成像。在斑马鱼中，我们发现了血管的新作用 血管内皮细胞生长因子c(VEGFC)在从背主动脉释放HSPC中的作用。VEGFC还规定了一种命运 在HSPC之前，决定它们将成为干细胞还是不同类型的祖细胞。在… 在后期，我们发现了整合素α4(Itga4)在尾部造血组织中的编程功能。 (CHT)，斑马鱼相当于胎肝。我们假设HSPC接触和转换的时间 在发育的小生境之间是它们正确编程的关键。我们将通过以下方式解决这一假设 具体目标如下：1)确定VEGFC在HSPC过渡和从背侧释放中的作用 大动脉。2)确定依赖itga4与CHT生态位计划的接触如何在HSPC过渡时进行 从胎儿期到成人期。我们将在体内进行基因敲除和小分子治疗， 结合实时成像，了解HSPC和利基细胞之间的动态相互作用。到时候我们会的 将这些结果转化为体外血管壁龛，用于将细胞分化为可移植的HSPC 这可能会导致对患者进行基于细胞的治疗。

PROJECT SUMMARY/ABSTRACT Hematopoietic stem and progenitor cell (HSPC) transplantation is a curative treatment for many blood diseases and cancers. However, these procedures still need to be optimized to improve patient outcomes and survival. HSPCs reside in a microenvironment surrounded by niche cells that help regulate their function. Our research proposal seeks to address fundamental questions regarding the cellular interactions between HSPCs and niche cells. During development in the embryo, HSPCs move through different tissues and have changing requirements for contact with the microenvironment. HSPCs first arise in the dorsal aorta, a large vessel in the embryo, and are then released into circulation. Next, HSPCs migrate to the fetal liver where the population of cells expands exponentially via symmetric divisions. Finally, HSPCs migrate again to colonize the bone marrow where they will remain throughout adulthood. As HSPCs are migrating between these different hematopoietic tissues, they are also becoming more mature and are programmed towards their adult quiescent state. We use zebrafish and mice as model systems that are highly conserved with humans and have many genetic tools for functional testing and live imaging of cellular behaviors. In zebrafish, we have found a novel role for vascular endothelial growth factor c (vegfc) in the release of HSPCs from the dorsal aorta. Vegfc also regulates a fate decision in pre-HSPCs that determines if they will become a stem cell or a different type of progenitor cell. At later stages, we found a programming function for integrin alpha 4 (itga4) in the caudal hematopoietic tissue (CHT), the zebrafish equivalent of the fetal liver. We hypothesize that the timing of HSPC contact and transitions between developmental niches is critical for their correct programming. We will address this hypothesis through the following Specific Aims: 1) Define the role of vegfc in HSPC transition and release from the dorsal aorta. 2) Determine how itga4-dependent contact with the CHT niche programs HSPCs as they transition from fetal-like to adult stages. We will perform in vivo genetic knockdown and small molecule treatments, together with live imaging, to understand the dynamic interactions between HSPCs and niche cells. We will then translate these results to an in vitro vascular niche that is used to differentiate cells into transplantable HSPCs that could lead to cell-based therapies for patients.