Embryonic stem cell-derived osteoprogenitor cells for bone formation and repair

描述(由申请人提供)：治疗骨骼疾病的新治疗方法仍然是一个关键的医学问题。诸如骨质疏松症、成骨不全、颅骨融合以及创伤性骨损伤等疾病已经通过使用成人间充质细胞或内皮祖细胞的基于细胞的方法来治疗。然而，这些研究的结果并不确定，目前还没有利用成体祖细胞进行的基于细胞的治疗转化为骨修复的常规临床实践。作为一种重要而新颖的方法，该提案将测试使用人类胚胎干细胞(HESCs)来创建一种创新的骨骼发育和修复模型。此外，这些人胚胎干细胞向成骨细胞分化的研究将为调节人类成骨细胞分化的基本细胞和遗传机制提供新的见解。反过来，这些研究将提供更多的方法来治疗遗传性和获得性骨形成障碍，如成骨不全和骨质疏松。我们课题组之前的研究表明，人类胚胎干细胞可以常规地分化为多种细胞系，包括造血祖细胞和其他中胚层前体细胞。在这里，我们将检验一个中心假设，即hESC来源的CD34+细胞是具有成骨潜力的中胚层前体细胞。这一假说的验证将通过开发hESC株来推进，hESC系被设计成表达由RUNX2启动子驱动的荧光报告分子，以便于识别介导成骨细胞发育的关键信号和发育途径。这些细胞还将使后续分析可能用于促进骨形成的药物，以及在骨折修复模型中测试hESC来源的MSCs和更多分化的骨祖细胞。本研究结果表明，人胚胎干细胞在体内外均能有效地分化为成骨细胞，为骨修复和骨发育研究提供了一种新的资源。 公共卫生相关性：据估计，超过1000万美国人患有骨质疏松症，所有骨折中有5%-10%的骨折合并有延迟愈合或骨不连，这表明骨形成疾病是一个严重的医疗问题。虽然各种基于细胞的治疗方法已经被测试用于骨骼疾病，但在现有的实验模型中使用的细胞类型(主要是成人间充质细胞或内皮祖细胞)存在固有的局限性。人类胚胎干细胞(HESCs)的来源和鉴定为理解与骨再生相关的机制和这些疾病的管理提供了独特的和潜在的非常重要的进展。

DESCRIPTION (provided by applicant): Novel therapeutic approaches to treat bone diseases remain a critical medical issue. Diseases such as osteoporosis, osteogenesis imperfecta and craniosynostosis, as well as traumatic bone injury have been treated utilizing cell-based approaches using adult mesenchymal or endothelial progenitor cells. However, results of these studies have been inconclusive, and currently no cell-based treatment utilizing adult progenitor cells has yet translated into routine clinical practice for bone repair. As an important and novel approach, this proposal will test the use of human embryonic stem cells (hESCs) to create an innovative model of bone development and repair. Additionally, these studies of hESC differentiation into osteogenic cells will shed new insights into basic cellular and genetic mechanisms that regulate human osteoblast differentiation. In turn, these studies will provide additional approaches to treat genetic and acquired disorders of bone formation, such as osteogenesis imperfecta and osteoporosis. Previous studies by our group demonstrate hESCs can be routinely supported to differentiate into multiple cellular lineages including hematopoietic and other mesodermal progenitor cells. Here we will test the central hypothesis that hESC-derived CD34+ cells serve as mesoderm progenitor cells with osteogenic potential. Testing this hypothesis will be advanced by developing hESC lines engineered to express fluorescent reporter molecules driven by the RUNX2 promoter to facilitate the identification of key signaling and developmental pathways that mediate the development of osteogenic cells. These cells will also enable subsequent analysis of agents that may be utilized to promote bone formation, as well as the testing of hESC- derived MSCs and more differentiated osteo-progenitor cells in a fracture repair model. This proposal will show that hESCs can efficiently differentiate into osteogenic cells in vitro and in vivo and that they can represent a novel resource for studies of bone repair and development. Public Health Relevance: It is estimated that more than 10 million Americans have osteoporosis, and that 5-10% of all fractures are complicated by delayed union or nonunion, thus indicating that diseases of bone formation represent a serious medical issue. While a variety of cell-based therapies have been tested for bone disorders, there are inherent limitations to the types of cells (principally adult mesenchymal or endothelial progenitor cells) that have been used in the existing experimental models. The derivation and characterization of human embryonic stem cells (hESCs) provides a unique and potentially highly significant advance in understanding the mechanisms pertaining to bone regeneration and the management of these conditions.