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首页> 外文学位 >The role of insulin-like growth factor-I (IGF-I) in regulating bone mass and its application in the cell-based gene therapy of bone.
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The role of insulin-like growth factor-I (IGF-I) in regulating bone mass and its application in the cell-based gene therapy of bone.

机译：胰岛素样生长因子-I（IGF-I）在调节骨量中的作用及其在骨骼的基于细胞的基因治疗中的应用。

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摘要

Insulin-like growth factor-I (IGF-I) is an important growth factor involved in embryonic and postnatal growth, skeletal development and bone remodeling. The goals of this work were to understand the role of IGF-I in growth and bone mass regulation during various stages of postnatal life, and to evaluate the use of IGF-I in cell-based gene therapy of bone. First, we analyzed the growth and skeletal phenotype in cohorts of wild type (igf1 +/+, WT) and igf1 heterozygous null (igf1 +/−, HET) mice in the outbred CD-1 background at 1, 2, 4, 8, 12, 15, and 18 months of age. HET mice were healthy and bred normally. They had decreased serum IGF-I levels (20–30% lower than WT) accompanied by reduced body weight, femur length, areal bone mineral density (BMD) and cortical bone area in most age groups with little change in trabecular bone volume. Serum IGF-I levels showed strong positive correlation with body weight, femur length and BMD. Primary osteoblasts from neonatal HET mice had significantly reduced IGF-I production, proliferation and differentiation capacity compared to WT cells. These results suggest that both circulating and skeletal IGF-I signaling are important in the acquisition and the maintenance of bone mass.; Next, to explore the therapeutic potential of IGF-I as an anabolic agent to stimulate bone formation, we developed a bicistronic retroviral system to deliver functional IGF-I in a bone-targeted manner for cell-based gene therapy. ROSA2.3-IGF-I/eGFP retrovirus was constructed to express both IGF-I and a visual marker—enhanced green fluorescent protein (eGFP) under the control of a 2.3 kb fragment of the rat Col1a1 promoter. Primary murine osteoblasts transduced with ROSA2.3-IGF-I/eGFP showed enhanced osteoblast differentiation. The effects of retroviral-delivered IGF-I on bone formation in vivo were assessed by an ectopic bone formation assay in which bone marrow stromal cells transduced with ROSA2.3-IGF-I/eGFP or control ROSA2.3-GFP retroviruses were implanted subcutaneously into nude CD-1 recipients. The expression of viral-delivered eGFP and IGF-I was detected in implant sections by fluorescent microscopy and immunohistochemistry six weeks after the surgery. Implants with ROSA2.3-IGF-I/eGFP-transduced cells showed higher bone volume than controls. In conclusion, characterization of HET mice revealed that both circulating and skeletal IGF-I play a critical role in the regulation of postnatal bone mass; bone-targeted overexpression of IGF-I by a retroviral gene delivery system may be applicable to cell-based somatic gene therapy to increase bone mass.
机译：胰岛素样生长因子-I（IGF-I）是一种重要的生长因子，参与胚胎和出生后的生长，骨骼发育和骨骼重塑。这项工作的目的是了解IGF-I在产后生活各个阶段在生长和骨量调节中的作用，并评估IGF-I在基于细胞的骨骼基因治疗中的应用。首先，我们分析了野生型（ igf1 + / +，WT）和 igf1 杂合无效（ igf1 +）的人群的生长和骨骼表型（-，HET）小鼠在1、2、4、8、12、15和18个月大的远距离CD-1背景中。 HET小鼠健康且正常繁殖。在大多数年龄组中，他们的血清IGF-I水平降低（比WT低20-30％），同时体重，股骨长度，面骨矿物质密度（BMD）和皮质骨面积减少，而小梁骨体积变化不大。血清IGF-I水平与体重，股骨长度和BMD呈强正相关。与WT细胞相比，来自新生HET小鼠的原代成骨细胞显着降低了IGF-I的产生，增殖和分化能力。这些结果表明，循环和骨骼肌IGF-I信号传导在骨量的获取和维持中均很重要。接下来，为了探索IGF-I作为促蛋白合成剂刺激骨形成的治疗潜力，我们开发了双顺反子逆转录病毒系统，以骨靶向的方式递送功能性IGF-I，用于基于细胞的基因治疗。构建了ROSA2.3-IGF-I / eGFP逆转录病毒，以在大鼠Col1a1启动子的2.3 kb片段的控制下表达IGF-I和视觉标记的增强型绿色荧光蛋白（eGFP）。用ROSA2.3-IGF-I / eGFP转导的原代鼠成骨细胞显示出增强的成骨细胞分化。通过异位骨形成试验评估逆转录病毒递送的IGF-I对体内骨形成的影响，其中将经ROSA2.3-IGF-I / eGFP或对照ROSA2.3-GFP逆转录病毒转导的骨髓基质细胞皮下植入进入裸CD-1接收者。术后六周，通过荧光显微镜和免疫组织化学检测植入物切片中病毒递送的eGFP和IGF-I的表达。具有ROSA2.3-IGF-1 / eGFP转导的细胞的植入物显示出比对照更高的骨量。总之，对HET小鼠的鉴定表明，循环中的IGF-I和骨骼中的IGF-I在调节产后骨量中都起着关键作用。逆转录病毒基因递送系统的骨靶向的IGF-1的过表达可能适用于基于细胞的体细胞基因治疗以增加骨量。

著录项

  • 作者

    He, Jianing.;

  • 作者单位

    The University of Connecticut.;

  • 授予单位 The University of Connecticut.;
  • 学科 Health Sciences Medicine and Surgery.; Biology Molecular.; Biology Animal Physiology.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 187 p.
  • 总页数 187
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 分子遗传学;生理学;
  • 关键词

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