Osteomacs and megakaryocytes interact to regulate hematopoietic stem cell function

骨巨细胞和巨核细胞相互作用调节造血干细胞功能

• 批准号: 9764740
• 负责人: Melissa A Kacena
• 金额: $ 31.7万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9764740
• 关键词: 3-Dimensional; ALCAM gene; Adult; Age; Blood Cells; Blood Platelets; Blood coagulation; Bone Marrow; Calvaria; Cell Maintenance; Cell physiology; Cells; Clinical Treatment; Competence; Complex; Critical Pathways; Cytometry; Data; Development; Elements; Embryo; Endosteum; Endothelial Cells; Engraftment; Erythropoiesis; Extracellular Matrix Proteins; Funding Opportunities; Genetic Models; Genomics; Goals; Health; Hematopoiesis; Hematopoietic; Hematopoietic Stem Cell Mobilization; Hematopoietic stem cells; In Vitro; Ionizing radiation; Lead; Maintenance; Malignant Neoplasms; Marrow; Mediating; Megakaryocytes; Modeling; Molecular; Mus; National Institute of Diabetes and Digestive and Kidney Diseases; Neonatal; Osteoblasts; PTPRC gene; Pathway interactions; Phenotype; Platelet Factor 4; Population; Property; Proteomics; Publishing; Radiation; Regulation; Research; Role; Signal Transduction; Stem cells; Structure; Surface; Testing; Time; Tissues; Transforming Growth Factors; Transplantation; Work; base; cell preparation; cell type; conditioning; hematopoietic stem cell niche; hematopoietic stem cell self-renewal; long bone; macrophage; mature animal; programs; recruit; spatial relationship; stem cell differentiation; transcriptome; transplant model

The hematopoietic niche is a complex structure of multiple cell types and extra-cellular matrix proteins. In a well-orchestrated manner, elements of the niche interact together and with hematopoietic stem cells (HSC) to maintain HSC selfrenewal potential. HSC maintenance within the bone marrow (BM) is associated with the health of cellular elements of the niche including endothelial cells, osteoblasts, and other hematopoietic cells such as megakaryocytes. Our published work demonstrates that immature osteoblasts mediate a robust in vitro hematopoiesis enhancing activity and that megakaryocytes enhance osteoblast proliferation and inhibit their differentiation. Megakaryocytes have been implicated in both regulating HSC function and maintaining the competence of the niche after radiation through specialized interactions with osteoblasts that augment their enhancement of HSC function. Recently, a unique population of CD45+F4/80+ macrophages known as osteomacs (OM) was recognized in the niche. We detected these cells in neonatal calvarial cell (NCC) preparations and recently published that OM are critical for the osteoblast-mediated hematopoiesis enhancing activity. Megakaryocytes stimulate NCC-derived OM as well as OM from adult mice and significantly enhance their in vitro expansion and function. Interestingly, extensive flow cytometric characterization of OM revealed that OM are phenotypically distinct from BM-derived macrophages and that the later cannot functionally substitute for OM to drive the osteoblast-mediated hematopoiesis enhancing activity. Our studies further suggest that OM are important for the competence of the hematopoietic niche. We hypothesize that maintenance of HSC function and the competence of the hematopoietic niche are dependent on cellular interactions and molecular cross talk between osteoblast, OM and megakaryocytes. Our hypothesis will be examined by investigating the following three aims: 1) Investigate if OM are transplantable and whether loss of megakaryocytes disrupts the emergence of OM and negatively impacts HSC function and niche competence. 2) Identify differences between OM and BM-derived macrophages that make OM a unique niche component and define, at the molecular level, how OM and megakaryocytes promote the maintenance of HSC function. 3) Define the spatial relationship between HSC, osteoblasts, OM, and megakaryocytes in the intact niche of young and old mice and in the perturbed microenvironment following marrow conditioning. The significance of these studies is that they will define and explain how the interplay between four cellular components of the BM regulate HSC function and the competence of the niche. The novelty derives from the potential of these studies to establish, for the first time, a unique group of cells, namely OM, as primary targets of the megakaryocyte-mediated HSC promoting activity in the niche. Our premise that OM are central to HSC and niche functional properties is both paradigm shifting in our understanding of the close interactions between HSC and the niche and is also an unexplored pathway critical to the maintenance of hematopoiesis.

造血生态位是多种细胞类型和细胞外基质蛋白的复杂结构。中 以精心策划的方式，生态位的元素相互作用，并与造血干细胞（HSC）， 维持HSC的自我更新潜能。HSC在骨髓（BM）中的维持与HSC的增殖有关。 包括内皮细胞、成骨细胞和其他造血细胞在内的生态位细胞成分的健康 如巨核细胞。我们已发表的工作表明，未成熟的成骨细胞介导了一个强大的， 体外造血增强活性和巨核细胞增强成骨细胞增殖并抑制 他们的区别。巨核细胞参与调节HSC功能和维持HSC的功能。 通过与成骨细胞的专门相互作用， HSC功能增强。最近，一个独特的CD 45 +F4/80+巨噬细胞群体被称为 骨肉瘤（osteomacs，OM）在龛位中被识别。我们在新生儿颅骨细胞（NCC）中检测到这些细胞 最近发表的研究表明，OM对于成骨细胞介导的造血增强至关重要。 活动巨核细胞刺激NCC来源的OM以及来自成年小鼠的OM，并显著增强 它们的体外扩增和功能。有趣的是，OM的大量流式细胞术表征揭示了 OM在表型上与BM衍生的巨噬细胞不同，后者在功能上不能 替代OM以驱动成骨细胞介导的造血增强活性。我们的研究进一步 表明OM对造血生态位能力是重要的。我们假设 HSC功能的维持和造血生态位的能力依赖于 成骨细胞、OM和巨核细胞之间的细胞相互作用和分子串扰。我们 本研究将通过以下三个目的来检验这一假设：1）研究OM是否可移植 以及巨核细胞的损失是否会破坏OM的出现并对HSC功能产生负面影响， 利基竞争力2)确定OM和BM源性巨噬细胞之间的差异，使OM成为一种独特的 在分子水平上，OM和巨核细胞如何促进微生态位的维持， HSC功能。3)确定HSC、成骨细胞、OM和巨核细胞之间的空间关系， 完整的生态位的年轻和年老的小鼠和在扰动的微环境后骨髓调节。的 这些研究的意义在于，它们将定义和解释四种细胞之间的相互作用， BM的组分调节HSC功能和生态位的能力。其新奇在于 这些研究有可能首次建立一组独特的细胞，即OM，作为主要靶点 巨核细胞介导的HSC促进活性的小生境。我们的前提是OM是HSC的核心 和生态位功能特性都是我们理解之间密切相互作用的范式转变， HSC和生态位也是一种未探索的对维持造血至关重要的途径。