Optimizing Normal Collagen Replacement in Osteogenesis Imperfecta

优化成骨不全患者的正常胶原蛋白替代

• 批准号: 8390315
• 负责人: SARAH L DALLAS
• 金额: $ 21.04万
• 依托单位: UNIVERSITY OF MISSOURI KANSAS CITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8390315
• 关键词: Age; Anabolic Agents; Animal Model; Area; Ascorbic Acid; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Bone Matrix; Bone Surface; Bone remodeling; COL1A1 gene; Cell Transplants; Cells; Child; Chimeric Proteins; Code; Collagen; Collagen Fibril; Collagen Gene; Cysteine; Data; Defect; Deposition; Disease; Donor person; Engraftment; Fracture; Fracture Healing; Genes; Green Fluorescent Proteins; Hereditary Disease; Hormones; Human; Inherited; Intervertebral disc structure; Knowledge; Label; Laboratories; Lead; Marrow; Measurement; Mechanics; Mus; Mutation; Osteoblasts; Osteogenesis Imperfecta; Parathyroid gland; Patients; Perinatal; Pharmaceutical Preparations; Property; Public Health; Reporter; Research; Skeleton; Skin; Stem cells; Tendon structure; Time; Transgenes; Transgenic Mice; Transplantation; ascorbate; bisphosphonate; bone; improved; in vivo; induced pluripotent stem cell; innovation; insight; mouse model; mutant; novel; novel strategies; osteoprogenitor cell; promoter; repaired; skeletal disorder; standard of care; tool; triple helix

DESCRIPTION (provided by applicant): Osteogenesis imperfecta (OI) is a genetic disorder in which the bones are extremely brittle and highly susceptible to fracture. Most cases of OI are caused by mutations in type I collagen genes that result in reduced amounts of normal collagen or structural defects of the triple helix, leading to abnormal fibril formation and/or assembly. Th disease spectrum in OI varies from severe forms with intrauterine fractures/perinatal lethality to mild forms without fractures. The current standard of care for OI is bisphosphonate treatment. However, recent concerns over the potential of these drugs to inhibit bone remodeling and impair fracture healing, as well as the lack of knowledge about the long term consequences of bisphosphonate treatment in children bring new urgency to the search for alternative OI therapies. Our laboratory has recently generated a "green collagen mouse" in which the collagen pro¿2(I) chain is fused with green fluorescent protein (GFP) and is expressed under control of the 3.6kb COL1A1 promoter for expression in osteoblasts in bone. Our preliminary data validating this novel ¿2(I)-GFP-collagen fusion protein have shown that it behaves similarly to the wild type form, is secreted upon addition of ascorbic acid, co-precipitates with collagen ¿1 chains, and is assembled into banded collagen fibril arrays. Mice expressing the GFP-collagen construct show green fluorescent collagen in the bone matrix, tendon, intervertebral discs and skin and appear phenotypically normal. These mice provide a novel and powerful new research tool with which to explore the utility of transplantation of whole marrow, stem cells or induced pluripotent stem cells (iPS) as potential therapies for repair of abnormal collagen in OI. In this exploratory R21, we plan to perform combined bone marrow transplantation of GFPcollagen expressing cells and osteoprogenitors into two mouse models of OI representing moderately severe and mild forms of OI. These include the oim mouse, which does not produce functional pro¿2(I) collagen chains and the G610C mouse, which carries a cysteine mutation in the ¿2(I) chain. The GFP-collagen expressing transplanted cells provide a powerful in vivo readout with which we can assess not only engraftment of donor cells, but also the degree of replacement of mutant (host) bone collagen with donor (GFP-positive) collagen. These innovative studies will determine the extent to which abnormal collagen can be replaced by the collagen from the transplanted cells as a function of time and explore potential approaches to enhance the extent and amount of collagen replacement through treatment with bone anabolic and antiresorptive agents. These studies have the potential to lead to novel or improved treatments for patients with OI. PUBLIC HEALTH RELEVANCE: This research is relevant to public health as it will investigate approaches for novel and/or improved treatments for the skeletal disorder, osteogenesis imperfecta. This is an inherited disease in which the bones are extremely brittle and prone to fracture due to mutations in genes that code for bone collagens. The research will use a new transgenic mouse we have developed, in which the bone collagen is fluorescently labeled green. Marrow and bone cells from these "green collagen mice" will be transplanted into mice with osteogenesis imperfecta mutations. We will determine how much of the diseased collagen is replaced by green collagen and investigate whether pharmacological agents can enhance the replacement of diseased collagen with green collagen from the transplanted cells.

描述（由申请人提供）：成骨不全症（OI）是一种遗传性疾病，其中骨骼极其脆弱且极易骨折。大多数 OI 病例是由 I 型胶原蛋白基因突变引起的，导致正常胶原蛋白含量减少。或三螺旋结构缺陷，导致原纤维形成和/或组装异常。 Th 疾病范围从伴有宫内骨折/围产期死亡的严重形式到不伴有骨折的轻度形式。然而，最近对这些药物抑制骨重塑和损害骨折愈合的潜力的担忧，以及对双磷酸盐治疗对儿童的长期后果缺乏了解，使得寻找替代性成骨不全症变得更加紧迫。我们的实验室最近培育出了一种“绿色胶原蛋白小鼠”，其中的胶原蛋白可生成。 2(I) 链与绿色荧光蛋白 (GFP) 融合，并在 3.6kb COL1A1 启动子的控制下表达，以便在骨中的成骨细胞中表达。 2(I)-GFP-胶原蛋白融合蛋白已显示其行为与野生型形式相似，在添加抗坏血酸后分泌，与胶原蛋白共沉淀 ¿ 1 表达 GFP 胶原蛋白结构的小鼠在骨基质、肌腱、椎间盘和皮肤中显示出绿色荧光胶原蛋白，并且表现出正常的表型。探索全骨髓、干细胞或诱导多能干细胞 (iPS) 移植作为修复 OI 中异常胶原蛋白的潜在疗法的效用。在这个探索性 R21 中，我们计划。将 GFP 胶原蛋白表达细胞和骨祖细胞联合骨髓移植到两种 OI 小鼠模型中，这些模型代表中度和轻度 OI 形式，其中包括不产生功能性蛋白的 oim 小鼠。 2(I) 胶原链和 G610C 小鼠，其 ¿ 中携带半胱氨酸突变表达 GFP 胶原蛋白的移植细胞提供了强大的体内读数，我们不仅可以评估供体细胞的植入，还可以评估供体（GFP 阳性）突变（宿主）骨胶原的替代程度。这些创新研究将确定移植细胞中的胶原蛋白替代异常胶原蛋白的程度随时间的变化，并探索通过骨合成代谢和抗吸收剂治疗来增强胶原蛋白替代程度和数量的潜在方法。这些研究有可能为成骨不全患者带来新的或改进的治疗方法。 公共健康相关性：这项研究与公共健康相关，因为它将研究骨骼疾病、成骨不全症的新颖和/或改进的治疗方法。这是一种遗传性疾病，骨骼极其脆弱，并且由于突变而容易骨折。该研究将使用我们开发的新型转基因小鼠，其中的骨胶原被荧光标记为绿色，来自这些“绿色胶原蛋白小鼠”的骨细胞将被移植到具有绿色胶原蛋白的小鼠体内。我们将确定有多少患病胶原蛋白被绿色胶原蛋白替代，并研究药物制剂是否可以增强来自移植细胞的绿色胶原蛋白对患病胶原蛋白的替代。