ROLE OF OSTEOBLASTS IN STEM CELL PROLIFERATION

描述（直接取自应用程序）：造血干细胞 细胞存活， 自我更新和分化被认为是高度依赖于 基质微环境，出生后主要限于 骨髓然而，对候选人骨髓的研究 迄今为止，基质细胞集中在相当普遍的细胞中， 成分，如成纤维细胞和内皮细胞。一样重要 这样的细胞可能在造血，他们的活动不能轻易 解释为什么造血集中在骨髓因此我们 最近开始关注一种特定的细胞类型，成骨细胞， 专门位于骨髓内的骨内膜表面 蛀牙根据我们的初步数据，成骨细胞似乎 直接与原始造血细胞沟通，并支持他们的 增殖我们建议深入探讨细胞和分子 成骨细胞-干细胞相互作用的基础。具体而言，我们计划： 1.原始细胞增殖和自我更新能力的比较 在成骨细胞单层上培养之前和之后的造血细胞， 利用： a.体外克隆形成和长期培养起始细胞测定;和 B.使用NOD/SCID异种移植的体内移植测定 宿主，通过有限稀释和系列移植试验; 2.确定骨髓微环境解剖的影响 （邻近造血细胞）和生理学（灌注）对成骨细胞 造血功能;以及 3.分子克隆成骨细胞来源的cDNA，其蛋白质产物 刺激原始人类造血细胞的增殖。 这些实验应该能全面地说明 造血作用的一个重要的，但以前没有特点的细胞， 骨髓微环境的作用，我们假设是 对造血干细胞的维持和自我更新至关重要。 在本计划项目应用程序的背景下，这些 调查将集中在骨髓的作用和机制， 微环境控制着原始干细胞的自我更新 细胞室

Description (taken directly from the application): Hematopoietic stem cell survival, self-renewal and differentiation is believed to be highly dependent on the stromal microenvironment, which after birth is largely restricted to the bone marrow. However, investigations of candidate bone marrow stromal cells to date have concentrated on fairly ubiquitous cellular elements, such as fibroblasts and endothelial cells. As important as such cells may be in hematopoiesis, their activities cannot easily explain why hematopoiesis concentrates in the marrow. We therefore have recently begun to focus on a specific cell type, the osteoblast, which is located specifically on the endosteal surface within bone marrow cavities. Based upon our preliminary data, osteoblasts appear to directly communicate with primitive hematopoietic cells and support their proliferation. We propose to explore in depth the cellular and molecular basis for osteoblast-stem interactions. Specifically, we plan to: 1. Compare of the proliferative and self-renewal capacity of primitive hematopoietic cells before and after culture on osteoblast monolayers, utilizing: a. In vitro clonogenic and long term culture initiating cell assays; and b. In vivo transplantation assays using NOD/SCID xenogeneic transplant hosts, via limiting dilution and serial transplantation assays; 2. Determine the effect of bone marrow microenvironmental anatomy (adjacent hematopoietic cells) and physiology (perfusion) on osteoblast hematopoietic function; and 3. Molecularly clone osteoblast derived cDNAs whose protein products stimulate the proliferation of primitive human hematopoietic cells. These experiments should give a comprehensive picture of the hematopoietic role of an important but previously uncharacterized cell in the bone marrow microenvironment, a role which we hypothesize to be central to the maintenance and self-renewal of hematopoietic stem cells. Within the context of this Program Project application, these investigations will focus on the role and mechanisms by which marrow microenvironments govern stem cell self-renewal of the primitive stem cell compartments.