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（Osteogenesis imperfecta， OI）是一种遗传性疾病，其骨骼非常脆弱，极易骨折。大多数成骨不全病例是由I型胶原基因突变引起的，这种突变导致正常胶原蛋白数量减少或三螺旋结构缺陷，导致纤维形成和/或组装异常。成骨不全的疾病谱系从伴有宫内骨折/围产期死亡的严重形式到无骨折的轻度形式不等。目前治疗成骨不全的标准是双膦酸盐治疗。然而，最近对这些药物可能抑制骨重塑和损害骨折愈合的担忧，以及对儿童双膦酸盐治疗的长期后果缺乏了解，使得寻找替代成骨不全症治疗的新紧迫性。我们实验室最近培育了“绿色胶原小鼠”，胶原蛋白亲2(I)链与绿色荧光蛋白（GFP）融合，在3.6kb COL1A1启动子的控制下在骨内成骨细胞中表达。我们验证这种新颖的¿2(I)- gfp -胶原融合蛋白的初步数据表明，它的行为与野生型相似，在添加抗坏血酸时分泌，与胶原蛋白共同沉淀