Role of Hemotopoietic Stem Cells in Periodontal Ligament Homeostasis

 描述（由申请人提供）：牙周病是一种慢性炎症性疾病，可导致组织的不可逆破坏，导致牙齿与其支持组织之间的附着丧失。在美国，几乎47.2%的成年人患有某种程度的牙周病。目前的牙周病治疗缺乏有效的促进再生的基本结构：牙槽骨，牙骨质和牙周膜（PDL）。几种策略正在实验测试，以提高牙周再生，其中之一是使用干细胞。鉴定合适的细胞接种到牙周缺损将是一个强大的工具，以促进再生。最近，研究表明PDL细胞可以来源于骨髓（BM）中的细胞。使用移植有来自单个增强型绿色荧光蛋白+（EGFP+）造血干细胞（HSC）的克隆群的小鼠，来自我们实验室的数据已经证明HSC可以产生多种组织成纤维细胞、脂肪细胞和成骨细胞。来自我们实验室的初步数据表明，GFP+细胞存在于移植有来自单个EGFP+ HSC的克隆群体的GFP-小鼠的PDL中。GFP与α-平滑肌肌动蛋白和骨钙素共定位，表明HSC可以在PDL中分化为成纤维细胞和成骨细胞。因此，本研究旨在验证HSC通过分化为PDL中的细胞在PDL周转和稳态中发挥作用的假设，并确定调节这种分化的因素。目的1将确定HSC对PDL的相对贡献，鉴定HSC产生的PDL中的亚群，并确定HSC在PDL周转/稳态中的参与。目的2的目标是描述由PDL中的HSC衍生的细胞表达或分泌的因子，然后检查所选因子对体外分选的HSC的分化/成熟的影响。通过完成这些研究，我们将建立和表征新的细胞来源HSC对PDL周转/稳态的相对贡献，并鉴定负责从HSC产生谱系的因子（已知或新的），从而鉴定用于增强HSC衍生的细胞参与PDL再生的靶点。这项研究的发现将是重要的，因为它们可以通过使用HSC在体内应用于增强疾病如牙周炎的组织愈合。这些初步研究将使我们能够测试这个激进的假设，并获得足够的初步数据，为随后的研究项目资助（R 01）的申请。

 DESCRIPTION (provided by applicant): Periodontal disease, a chronic inflammatory disease, can result in irreversible destruction of tissues leading to a loss of attachment between teeth and their supporting tissues. Almost 47.2% adults have some degree of periodontal disease in the US. Current treatments for periodontal disease lack efficacy in promoting the regeneration of the essential structures: alveolar bone, cementum and the periodontal ligament (PDL). Several strategies are being tested experimentally to enhance periodontal regeneration, one of them being the use of stem cells. Identification of suitable cells for seeding into periodontal defects would be a powerful tool to promote regeneration. Recently, studies have shown that PDL cells can be derived from cells in the bone marrow (BM). Using mice transplanted with a clonal population derived from a single enhanced green fluorescent protein+ (EGFP+) hematopoietic stem cell (HSC), data from our lab has demonstrated that the HSCs can give rise to several tissue fibroblasts, adipocyte and osteoblasts. Preliminary data from our lab demonstrates the presence of GFP+ cells in the PDL of GFP- mice transplanted with a clonal population derived from a single EGFP+ HSC. The GFP co-localized with a-smooth muscle actin and osteocalcin, indicating that HSCs may differentiate into fibroblasts and osteoblasts in the PDL. Thus, this proposal is to test the hypothesis that HSCs play a role in the PDL turnover and homeostasis by differentiating into the cells in the PDL and also to identify the factors regulating this differentiation. Aim 1 will determine the relative contribution of HSCs to the PDL, identify the sub-population (s) in the PDL that the HSCs give rise to and determine the participation of the HSCs in the PDL turnover/homeostasis. The goal of Aim 2 is to delineate the factors expressed or secreted by the HSC-derived cells in the PDL and then examine the effect of selected factors on the differentiation/maturation of sorted HSCs in vitro. By the completion of these studies, we will have established and characterized the relative contribution of a novel source of cells, HSCs, to PDL turnover/homeostasis and identified factors (known or new) responsible for generation of the lineages from the HSCs, thereby identifying targets for enhancing HSC-derived cell participation in PDL regeneration. Findings from this study will be significant in tha they can be applied in vivo to enhance healing of the tissue in diseases such as periodontitis through the use of the HSCs. These initial studies will allow us to test this radical hypothesis and obtain sufficient preliminary data for subsequent Research Project Grant (R01) application.