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

项目总结/摘要 造血干细胞（HSC）移植是许多血液疾病和癌症的治愈性治疗。 然而，这些程序仍然需要优化，以改善患者的结果和生存。在某种程度上， 由于我们对供体造血干细胞在移植后如何与受体骨髓相互作用的理解不足， 移植这项研究计划旨在解决有关细胞的基本问题， HSC和niche细胞之间的相互作用。根据我们以前的数据，我们已经表明，利基不 仅指示HSC，但HSC也将指导性线索传递给小生境。其中包括触发 将周围的内皮细胞重塑成“拥抱”HSC的支持性口袋。以更好地描述 这种新的细胞结构，我们结合了多种成像方式，以产生第一个相关的光， 内源性干细胞在其龛位的电子显微镜数据。从那以后，我们进行了功能性遗传学研究， 这些研究为这种结构的形成提供了机理上的见解。这些初步结果导致 本研究的主要目的是：1）确定HSC旁分泌信号介导EC的机制 2）确定粘附HSC-EC生态位相互作用的机制 促进HSC库的信号传导和稳定扩增。我们将进行体内基因敲除 和小分子治疗，以及实时成像，以了解HSC之间的动态相互作用， 和内皮细胞。然后，我们将这些结果转化为一个体外血管生态位的潜力，扩大 造血干细胞移植前。最终，我们希望我们的研究将导致改善临床HSC移植 协议.

PROJECT SUMMARY/ABSTRACT Hematopoietic stem cell (HSC) 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. In part, we have been limited by our poor understanding of how donor HSCs interact with the recipient bone marrow after transplantation. This research proposal seeks to address fundamental questions regarding the cellular interactions between HSCs and niche cells. Based on our previous data, we have shown that the niche not only instructs HSC, but that HSC also transmit instructive cues to the niche. These include triggered remodeling of surrounding endothelial cells into a supportive pocket that “cuddles” the HSC. To better describe this novel cellular structure, we combined multiple imaging modalities to produce the first correlative light and electron microscopy data of an endogenous stem cell in its niche. We have since performed functional genetic studies that provided mechanistic insight into the formation of this structure. These preliminary results have led us to pursue the following Specific Aims: 1) Identify the HSC-derived paracrine signals that mediate EC remodeling to form a niche for HSCs; 2) Identify mechanisms of adhesive HSC-EC niche interactions that promote signaling and stable expansion of the HSC pool. We will perform in vivo genetic knockdown and small molecule treatments, together with live imaging, to understand the dynamic interactions between HSC and endothelial cells. We will then translate these results to an in vitro vascular niche with the potential to expand HSCs prior to transplantation. Ultimately, we hope our studies will lead to improved clinical HSC transplantation protocols.