REGULATED OSTEOINDUCTIVE PLASMID GENE TRANSFER VIA GENE

仍然需要一种安全有效的骨替代物， 牙科和骨科：骨移植材料难以工作 与同种异体移植物可能是不安全的;新骨生长的速度 与骨移植相关的是不可接受的缓慢;长期 骨移植替代物的稳定性值得怀疑， 令人无法接受的缓慢;和移植材料（或移植物）的承诺 替代物）增加了生物物质（例如，成骨 细胞因子）尚未实现。 一个交付系统（GAM）已经 开发了骨诱导质粒基因， 可模制的、可生物降解的结构基质。 成功的可行性 已经在大鼠和犬模型中进行了研究，这项工作已经 第一次证明新骨在体内会迅速形成 在直接骨诱导质粒基因转移到成纤维细胞后， 参与骨骼修复。 可行性研究支持了一个总体假设，即快速新 通过GAM骨诱导质粒基因可诱导骨形成 转移 然而，一个一致的发现是， 大的骨缺损是最后和最困难的区域， 再生 因为全层再生对临床至关重要， 成功后，这项拨款申请提出了一系列跨学科的研究 旨在了解GAM基因机制的实验 转移 从本质上讲，我们认为， 大截骨缺损只能通过增加 了解与质粒基因相关的基本机制 转移 在本申请中要探索的具体假设是，GAM 可以预先设计结构，以增加 基因修饰的成纤维细胞，因此， 在体内形成的新骨。 对此，一系列理性的 对GAM质粒DNA和GAM结构基质的修饰是 具体目标（1-2）。 通过研究这些变化， 对GAM基因转移机制的重要新见解将是 获得。 这些修饰如何影响成骨细胞的行为 将在细胞培养模型系统中测量随后的基因转移 体外（具体目标3）。 从这些措施中，我们应该获得新的 深入了解新骨形成的生物学过程。 虽然可能 在本申请的范围之外，长期目标将是 为了测量合理预先设计的GAM结构在 体内使用建立的骨缺损动物模型。

The need for a safe and effective bone substitute still exists in dentistry and orthopedics: bone graft materials are difficult to work with and allografts may be unsafe; the rate of new bone growth associated with bone grafts is unacceptably slow; the long-term stability of bone graft substitutes is doubtful and osteoconduction is unacceptably slow; and the promise of a graft material (or graft substitute) augmented with a biological substance (e.g., osteogenic cytokine) has yet to be realized. A delivery system (GAM) has been developed in which osteoinductive plasmid genes are delivered from a moldable, biodegradable structural matrix. Successful feasibility studies have been conducted in rat and canine models, and this work has shown for the first time that new bone will form rapidly in vivo following direct osteoinductive plasmid gene transfer to fibroblasts involved in skeletal repair. The feasibility studies support an overall hypothesis that rapid new bone formation can be induced via GAM osteoinductive plasmid gene transfer. However, a consistent finding has been that the center of a large osseous defect is the last and most difficult region to regenerate. Because full-thickness regeneration is crucial to clinical success, this grant application proposes a series of interdisciplinary experiments that are designed to understand the mechanism of GAM gene transfer. In essence, we believe that full- thickness regeneration of large osteotomy defects will only be realized through an increased understanding of the basic mechanisms associated with plasmid gene transfer. The specific hypothesis to be explored in this application is that GAM constructs can be pre-designed so as to increase the percentage of genetically modified fibroblasts and, therefore, the rate and amount of new bone that forms in vivo. In this regard, a series of rational modifications to the GAM plasmid DNA and the GAM structural matrix are proposed (Specific Aims 1-2). By studying these modifications, important new insights into the mechanism of GAM gene transfer will be gained. How these modifications affect the behavior of osteogenic cells following gene transfer will be measured in a cell culture model system in vitro (Specific Aim 3). From these measures we should gain new insight into the biological process of new bone formation. While likely beyond the scope of the present application, a long term goal will be to measure the efficacy of rationally pre-designed GAM constructs in vivo using established bone defect animal models.