Multipotent lung mesenchymal cells in neonatal lung injury

描述（由申请人提供）： 我们已经获得了初步数据，表明来自因呼吸窘迫综合征（RDS）接受机械通气的一周大早产儿的气管吸出物含有集落形成成纤维细胞样细胞，其具有通常在间充质干细胞中发现的表面标记和分化潜能。Stro-1、CD 73、CD 90、CD 105和CD 166阳性，而CD 34、CD 45和CD 11b阴性，表明它们是间质而不是造血来源的。此外，它们表现出充足的增殖能力，并能够分化成骨细胞、脂肪细胞和肌成纤维细胞。来自这些细胞的条件培养基增强上皮生长和修复，抑制鳞状分化，并含有碱性成纤维细胞生长因子（bFGF/FGF-2）、角质形成细胞生长因子（KGF）和血管内皮细胞生长因子（VEGF）。最后，从患有RDS的早产儿的气管吸出物中分离多能间充质细胞与长期需要补充O2和慢性肺病的发展有关，即，支气管肺发育不良（BPD）。因此，我们假设多能肺间充质细胞参与新生儿肺修复，是肺损伤的生物标志物。为了验证这个假设，我们提出了以下具体目标。 具体目标1：确定早产儿多能肺间充质细胞被招募到气道的机制。我们假设上皮损伤诱导bFGF和单核细胞趋化蛋白（MCP）-1的表达，从而促进肺间充质细胞迁移到气隙。具体目标2：表征多能肺间充质细胞参与肺修复的潜在机制。我们假设：1）肺间充质细胞产生能够促进呼吸道上皮修复的营养因子; 2）当被转化生长因子（TGF）-β 1刺激时，肺间充质细胞分化成肌成纤维细胞，从而促进血管生成和纤维形成。 具体目标3：早产儿多能肺间充质细胞的存在与慢性肺病的发展和严重程度相关。我们假设多能肺间充质细胞是肺损伤和持续性肺功能障碍的生物标志物。我们将前瞻性地比较分离出多能肺间充质细胞的早产儿与未分离出多能肺间充质细胞的早产儿的临床结局，重点关注呼吸系统顺应性和供氧天数。了解多能肺间充质细胞在BPD发病机制中的作用将有助于改善这种疾病的治疗。

DESCRIPTION (provided by applicant): We have obtained pilot data demonstrating that tracheal aspirates from week-old premature infants undergoing mechanical ventilation for respiratory distress syndrome (RDS) contain colony-forming fibroblast- like cells with surface markers and differentiation potential typically found in mesenchymal stem cells. The cells are positive for Stro-1, CD73, CD90, CD105 and CD166, but negative for CD34, CD45 and CD11b, suggesting that they are of stromal but not hematopoietic origin. Further, they exhibit ample proliferative capacity and are capable of differentiation into osteocytes, adipocytes and myofibroblasts. Conditioned medium from these cells enhances epithelial growth and repair, inhibits squamous differentiation and contains basic fibroblast growth factor (bFGF/FGF-2), keratinocyte growth factor (KGF) and vascular endothelial cell growth factor (VEGF). Finally, the isolation of multipotent mesenchymal cells from the tracheal aspirates of premature infants with RDS is associated with a prolonged requirement for supplemental 02 and the development of chronic lung disease, i.e., bronchopulmonary dysplasia (BPD). We therefore hypothesize that multipotent lung mesenchymal cells participate in neonatal lung repair and are a biomarker for lung injury. To test this general hypothesis, we propose the following Specific Aims. Specific Aim 1: Determine mechanisms by which multipotent lung mesenchymal cells from premature infants are recruited to the airspaces. We hypothesize that epithelial injury induces expression of bFGF and monocyte chemoattractant protein (MCP)-1, thereby promoting lung mesenchymal cell migration to the airspaces. Specific Aim 2: Characterize potential mechanisms by which multipotent lung mesenchymal cells participate in lung repair. We hypothesize that: 1) lung mesenchymal cells produce trophic factors capable of promoting respiratory epithelial repair; 2) when stimulated by transforming growth factor (TGF)-fl, lung mesenchymal cells differentiate into myofibroblasts, thereby promoting angiogenesis and fibrogenesis. Specific Aim 3: Correlate the presence of multipotent lung mesenchymal cells in premature infants with the development and severity of chronic lung disease. We hypothesize that multipotent lung mesenchymal cells are biomarkers for lung injury and persistent pulmonary dysfunction. We will prospectively compare the clinical outcomes of premature infants from whom multipotent lung mesenchymal cells have been isolated with those from whom cells are not isolated, focusing on respiratory system compliance and days of oxygen supplementation. Understanding the role of multipotent lung mesenchymal cells in the pathogenesis of BPD will lead to improvements in the treatment of this disease.