GENE THERAPY FOR RECONSTRUCTING PERIODONTAL TISSUES

由于牙周病而丢失的组织，即骨、牙骨质和功能性牙周韧带，可以使用现有的牙周治疗方法在一定程度上得到恢复。然而，结果往往令人失望，因此，有必要开发新的范例再生牙周组织。细胞移植和基因转移的先进技术使我们能够提出关键的问题，即在体外和体内调节牙周细胞的细胞和分子机制。对这些问题的回答将导致改进用于再生牙周组织的策略。根据迄今的研究，我们推测，将编码血小板衍生生长因子(PDGF)和/或骨形态发生蛋白-7(BMP-7)的腺病毒载体导入成牙骨质细胞，然后将其整合到三维可生物降解聚合物中用于临床应用，将会改善再生治疗的结果。这一假说得到以下结果的支持：a)培养的成牙骨质细胞表达与促进就地牙骨质形成的类似细胞相关的基因，并且培养的成牙骨质细胞在7天内诱导形成矿物质结节；b)PDGF和BMP-7在体外可增强牙周细胞的功能，并在体内促进牙周组织的再生；以及c)可生物降解的聚合物能够监测因子在局部部位的释放，并与体内的伤口愈合相适应。这一假说将在三个特定目标下进行验证：L)确定编码骨形态发生蛋白-7和骨形态发生因子的腺病毒载体在体外对成牙骨质细胞的转导效率；2)建立体外促进牙骨质形成的合适环境；以及3)证明成牙骨质细胞在体内可以再生牙骨质，此外，骨形态发生因子和/或骨形态发生因子-7的表达可以促进再生。从这些研究中获得的知识将对使用基因治疗技术修复牙周组织和其他矿物质相关组织产生新的见解。

Tissues lost as a consequence of periodontal disease, i.e., bone, cementum and a functional PDL, can be restored to some degree using existing periodontal therapies. Nevertheless, results are often disappointing and therefore, there is a need to develop new paradigms for regenerating periodontal tissues. Advanced technologies in cell transplantation and gene transfer enable us to ask critical questions as to the cellular and molecular mechanisms regulating periodontal cells both in vitro and in vivo. Answers to these questions will result in improved strategies for use in regenerating periodontal tissues. Based on studies to date we hypothesize that adenoviral constructs encoding either platelet-derived growth factor (PDGF) and/or bone morphogenetic protein-7 (BMP-7) transfected into cementoblasts and then incorporated into three dimensional biodegradable polymers for clinical application will improve outcomes of regenerative therapy. This hypothesis is supported by results indicating that: a) cultured cementoblasts express genes associated with comparable cells that promote cementum formation in situ, and that cultured cementoblasts induce mineral nodule formation within 7 days; b) PDGF and BMP-7 enhance periodontal cell function, in vitro and promote periodontal regeneration, in vivo; and c) biodegradable polymers allow for monitored release of factors to a local site and are compatible with wound healing, in vivo. This hypothesis will be tested under three specific aims: l) To determine transduction efficiency of adenoviral constructs, encoding BMP-7 and PDGF, into cementoblasts in vitro; 2) To establish the appropriate environment for promoting cementogenesis in vitro; and 3) To prove that cementoblasts regenerate cementum, in vivo and furthermore, that expression of PDGF and/or BMP-7 enhance regeneration. Knowledge gained from these studies will produce new insights into the use of gene therapy technologies to restore the periodontium as well as other mineral-associated tissues.