Perivascular Cell Characterization and Contribution to the Hematopoietic Niche

描述（由申请人提供）：摘要理解造血细胞生态位环境对我们理解造血作用非常重要。据推测，间充质基质细胞（MSC）建立造血生态位，但其在体内的鉴定和表征尚未完成。目前的想法表明，MSC来源于血管周围细胞。已知MSC分泌大量的基质衍生因子-1（SDF 1），一种参与造血细胞募集和维持的趋化因子。我们已经在斑马鱼中创建了第一个SDF 1报告基因转基因脊椎动物，并且先前表明高SDF 1分泌细胞实际上是血管周围细胞，并且有助于过继转移后SDF 1招募造血细胞。该模型允许，第一次，分离造血小生境细胞的先验。我们假设血管周围细胞在体外培养扩增环境中产生MSC，并在体外和体内建立造血细胞生态位环境。 这项工作的主要目的是表征血管周围细胞的生化和功能。在特定的AIM 1中，我们将确定从sdf 1：DsRed转基因斑马鱼分离的血管周围细胞的体外性质，并且在特定的AIM 2中，我们将确定血管周围细胞支持体外造血细胞扩增的潜力。之前对MSC的表征主要集中在中胚层标志物和中胚层分化（骨生成、血管生成和脂肪生成）的检测上。使用分离和培养的血管周围细胞，我们将验证细胞表面标记，并将其分化为中胚层谱系。此外，我们将表明，血管周围细胞可以支持造血细胞在体外的生长/维持。 利用转基因斑马鱼的好处是可视化的血管周围的细胞在体内和特定的AIM 3，我们将确定血管周围的细胞在维持造血细胞的生态位在体内的作用。为了确定血管周围细胞的功能意义，我们将构建sdf启动子驱动的白喉毒素受体转基因鱼，其将允许靶向消融血管周围小生境细胞。随后将过继转移标记的供体骨髓，以使用目视显微镜测定和定量归巢测定来定量血管周围龛消融对归巢的影响。本文概述的实验方法将有助于我们更好地了解造血微环境。

DESCRIPTION (provided by applicant): Abstract Comprehending the hemopoietic cell niche environment is important in our understanding of hematopoiesis. It has been hypothesized that mesenchymal stromal cells (MSC) establish the hematopoietic niche, but their identification and characterization in vivo has not been accomplished. Current thinking suggests that MSC are derived from perivascular cells. MSC are known to secrete high amounts of stroma- derived factor-1 (SDF1), a chemokine involved in the recruitment and maintenance of hematopoietic cells. We have created the first SDF1 reporter transgenic vertebrate in a zebrafish and previously shown that high-SDF1 secreting cells were, in fact, perivascular cells and contribute to SDF1-recruitment of hematopoietic cells after adoptive transfer. This model allows, for the first time, the isolation of hematopoietic niche cells a priori. We hypothesize that perivascular cells give rise to MSC in the ex vivo culture expansion setting and establish the hematopoietic cell niche environment in vitro and in vivo. The primary aim of this work is to characterize perivascular cells both biochemically and functionally. In specific AIM 1, we will determine the in vitro properties of perivascular cells isolated from the sdf1:DsRed transgenic zebrafish and in specific AIM 2 we will determine the potential of perivascular cells to support hematopoietic cell expansion in vitro. Prior characterization of MSC has been focused on detection of mesodermal markers and mesodermal differentiation (osteogenesis, vasculogenesis, and adipogenesis). Using isolated and cultured perivascular cells we will verify cell surface markers and differentiate them into mesodermal lineages. Furthermore, we will show that perivascular cells can support the growth/maintenance of hematopoietic cells in vitro. The benefit of utilizing a transgenic zebrafish is the visualization of the perivascular cells in vivo and in specific AIM 3, we will determine the role of perivascular cells in the maintenance of the hematopoietic cell niche in vivo. To determine the functional significance of perivascular cells, we will construct an sdf promoter driven diphtheria toxin receptor transgenic fish that will allow targeted ablation of the perivascular niche cells. This will be followed by adoptive transfer of labeled donor marrow to quantify the effects of perivascular niche ablation on homing using both visual microscopic assays and quantitative homing assays. The experimental approach outlined here wills us to better understand the hematopoietic microenvironment.