Maintenance of the Hematopoietic Stem Cell Niche Monocytes and Macrophages

描述(申请人提供)：动员外周血中的造血干细胞和祖细胞(HSPC)使骨髓(BM)移植的供体细胞采集更加方便，并提高了细胞产量和植入率。G-CSF对HSPC的动员是通过调节干细胞生态位来实现的，干细胞生态位是维持和调节HSPC的骨髓微环境。文献中有许多暗示，单核细胞和巨噬细胞控制着造血生态位。这项应用建议研究M-CSF受体(CD115)表达的细胞在维持HSC生态位中的作用。我们的初步数据表明，G-CSF减少了骨髓单核细胞和巨噬细胞的数量，在体内这些群体的耗竭与HSPC动员和减少HSPC保留趋化因子BM CXCL12有关。在这项提案中，1)将在另外两个CD115+细胞耗竭的体内模型中确认这种相关性，b)确定介导串扰的因素(通过CD115+细胞与小鼠骨髓基质细胞系共培养的微阵列和培养上清的蛋白质阵列)，c)确定CDI 15耗竭诱导的HSPC动员对交感神经系统的依赖性(使用交感神经切除的药理学、外科和遗传学模型)，以及d)阐明这种动员与其他动员剂(G-CSF和AMD3100)的协同作用。对于AIMS a、c、d、e，我将通过集落形成实验评估HSPC的动员，通过流式细胞仪检测CD115+细胞的减少，用ELISA法评估CXCL12趋化因子的减少。与公共卫生相关：尽管干细胞动员使获取供移植的供体细胞变得更加方便和高效，但它在高达40%的患者中产生了干细胞数量不足的情况。拟议的实验可能会导致针对骨髓单核细胞和巨噬细胞的新策略的开发，以最大限度地提高干细胞产量。该项目的结果也对维持非造血干细胞生态位具有广泛的意义，其操作可有助于促进损伤后的组织修复，如心肌梗死、创伤性烧伤和神经变性。

DESCRIPTION (provided by applicant): Mobilization of hematopoietic stem and progenitor cells (HSPCs) into the peripheral blood has made harvest of donor cells for bone marrow (BM) transplantations more convenient and improved cell yield and engraftment. HSPC mobilization by G-CSF (Filgrastim) is mediated by modulation of the stem cell niche, which is the BM microenvironment that retains and regulates HSPCs. There have been many hints in the literature that monocytes and macrophages control the hematopoietic niche. This application proposes to study the role of the M-CSF receptor (CD115)-expressing cells in the maintenance of the HSC niche. Our preliminary data indicates that G-CSF reduces BM monocyte and macrophage numbers and in vivo depletion of these populations is correlated with HSPC mobilization and reduction in BM CXCL12, an HSPC retention chemokine. In this proposal, 1 will a) confirm this correlation in two additional in vivo models of CD115+ cell depletion, b) identify the factors mediating cross-talk (via microarray of CD115+ cells co-cultured with a murine BM-derived stromal cell line and protein array of culture supernatant), c) determine dependence of CDI 15-depletion-induced mobilization of HSPC on the sympathetic nervous system (using pharmacological, surgical and genetic models of sympathectomy), and d) elucidate synergy of this mobilization with other mobilizing agents (G-CSF and AMD3100). For aims a, c, d, e, I will assess HSPC mobilization by colony forming assays, CD115+ cell reduction by flow cytometry, and reduction in CXCL12 chemokine by ELISA. PUBLIC HEALTH RELEVANCE: While stem cell mobilization has made retrieval of donor cells for transplants more convenient and efficient, it yields an insufficient number of stem cells in up to 40% of patients. The experiments proposed can potentially lead to the development of new strategies targeting the BM monocytes and macrophages to maximize stem cell yield. The results of this project also has broad implications for the maintenance of non-hematopoietic stem cell niches, whose manipulation can be instrumental in facilitating tissue repair after injuries, such as myocardial infarction, traumatic burns, and neurodegeneration.